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SYNOPSIS

       barchart pathName ?option value?...


DESCRIPTION

       The  barchart  command creates a bar chart for plotting two-dimensional
       data (X-Y coordinates). A bar chart is a  graphic  means  of  comparing
       numbers by displaying bars of lengths proportional to the y-coordinates
       of the points they represented.  The bar chart  has  many  configurable
       components: coordinate axes, elements, legend, grid lines, cross hairs,
       etc.  They allow you to customize the look and feel of the graph.


INTRODUCTION

       The barchart command creates a new window for plotting  two-dimensional
       data  (X-Y coordinates), using bars of various lengths to represent the
       data points.  The bars are drawn in a rectangular area displayed in the
       center  of  the new window.  This is the plotting area.  The coordinate
       axes are drawn in  the  margins  surrounding  the  plotting  area.   By
       default,  the  legend  is drawn in the right margin.  The title is dis-
       played in top margin.

       A barchart widget has several configurable components: coordinate axes,
       data elements, legend, grid, cross hairs, pens, postscript, and annota-
       tion markers.  Each component can be queried or modified.

       axis       Up to four coordinate axes (two X-coordinate and two Y-coor-
                 dinate axes) can be displayed, but you can create and use any
                 number of axes. Axes control what region of data is displayed
                 and  how  the  data is scaled. Each axis consists of the axis
                 line, title, major and minor ticks,  and  tick  labels.  Tick
                 labels display the value at each major tick.

       crosshairs
                 Cross  hairs  are used to position the mouse pointer relative
                 to the X and Y  coordinate  axes.  Two  perpendicular  lines,
                 intersecting  at  the  current  location of the mouse, extend
                 across the plotting area to the coordinate axes.

       element   An element represents a set of data to be plotted.   It  con-
                 tains  an  x  and  y  vector  of values representing the data
                 points.  Each data point is displayed  as  a  bar  where  the
                 length  of the bar is proportional to the ordinate (Y-coordi-
                 nate) of the data point.  The appearance of the bar, such  as
                 its color, stipple, or relief is configurable.

                 A  special  case exists when two or more data points have the
                 same abscissa (X-coordinate).  By default, the bars are over-
                 layed,  one  on  top of the other.  The bars are drawn in the
                 order of the element display list.  But you can also  config-
                 ure  the bars to be displayed in two other ways.  They may be
                 displayed as a stack, where each bar (with the same abscissa)
                 is  stacked  on  the previous.  Or they can be drawn side-by-
                 side as thin bars.  The width of each bar is  a  function  of

       pen       Pens define attributes for elements.  Data elements use  pens
                 to  specify how they should be drawn.  A data element may use
                 many pens at once.  Here the particular pen used for  a  data
                 point  is  determined  from each element's weight vector (see
                 the element's -weight and -style options).

       postscript
                 The widget can generate encapsulated PostScript output.  This
                 component has several options to configure how the PostScript
                 is generated.


SYNTAX

       barchart pathName ?option value?...  The barchart command creates a new
       window  pathName and makes it into a barchart widget.  At the time this
       command is invoked, there must not exist a window named  pathName,  but
       pathName's  parent  must exist.  Additional options may be specified on
       the command line or in the option database to configure aspects of  the
       graph  such  as its colors and font.  See the configure operation below
       for the exact details about what option and value pairs are valid.

       If successful, barchart returns the path name of the widget.   It  also
       creates  a  new Tcl command by the same name.  You can use this command
       to invoke various operations that query or modify the graph.  The  gen-
       eral form is: pathName operation ?arg?...  Both operation and its argu-
       ments determine the exact behavior  of  the  command.   The  operations
       available  for  the graph are described in the BARCHART OPERATIONS sec-
       tion.

       The command can also be used to access components of the graph.   path-
       Name component operation ?arg?...  The operation, now located after the
       name of the component, is the function to be performed on  that  compo-
       nent. Each component has its own set of operations that manipulate that
       component.  They will be described below in their own sections.


EXAMPLE

       The barchart command creates a new bar  chart.   #  Create  a  new  bar
       chart.   Plotting  area  is black.  barchart .b -plotbackground black A
       new Tcl command .b is created.  This command can be used to  query  and
       modify the bar chart.  For example, to change the title of the graph to
       "My Plot", you use the new command  and  the  configure  operation.   #
       Change  the title.  .b configure -title "My Plot" To add data elements,
       you use the command and the element component.  # Create a new  element
       named  "e1" .b element create e1 \      -xdata { 1 2 3 4 5 6 7 8 9 10 }
       \       -ydata  {  26.18  50.46  72.85  93.31  111.86   128.47   143.14
                 155.85  166.60  175.38  }  The  element's X-Y coordinates are
       specified using lists of numbers.  Alternately, BLT  vectors  could  be
       used to hold the X-Y coordinates.  # Create two vectors and add them to
       the barchart.  vector xVector yVector xVector set { 1 2 3 4 5 6 7  8  9
       10  } yVector set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
            166.60 175.38 } n.b element create e1 -xdata xVector -ydata  yVec-
       tor  The  advantage  of  using vectors is that when you modify one, the
       sure we change the bar width  too.   .b  configure  -barwidth  0.2  The
       height  of  each  bar is proportional to the ordinate (Y-coordinate) of
       the data point.

       If two or more data points have the same abscissa (X-coordinate value),
       the  bars  representing those data points may be drawn in various ways.
       The default is to overlay the bars, one  on  top  of  the  other.   The
       ordering  is  determined  from  the  of  element  display list.  If the
       stacked mode is selected (using the -barmode configuration option), the
       bars  are stacked, each bar above the previous.  # Display the elements
       as stacked.  .b configure -barmode  stacked  If  the  aligned  mode  is
       selected,  the bars having the same x-coordinates are displayed side by
       side.  The width of each bar is a fraction of its normal  width,  based
       upon the number of bars with the same x-coordinate.  # Display the ele-
       ments side-by-side.  .b configure -barmode aligned By default, the ele-
       ment's  label in the legend will be also e1.  You can change the label,
       or specify no legend entry, again using the element's configure  opera-
       tion.   #  Don't  display  "e1" in the legend.  .b element configure e1
       -label "" You can configure more than just  the  element's  label.   An
       element  has many attributes such as stipple, foreground and background
       colors, relief, etc.  .b element  configure  e1  -fg  red  -bg  pink  \
            -stipple gray50 Four coordinate axes are automatically created: x,
       x2, y, and y2.  And by default, elements are mapped onto the axes x and
       y.   This  can be changed with the -mapx and -mapy options.  # Map "e1"
       on the alternate y axis "y2".  .b element configure e1  -mapy  y2  Axes
       can  be configured in many ways too.  For example, you change the scale
       of the Y-axis from linear to log using the axis component.  # Y-axis is
       log  scale.   .b  axis configure y -logscale yes One important way axes
       are used is to zoom in on a particular data region.  Zooming is done by
       simply specifying new axis limits using the -min and -max configuration
       options.  .b axis configure x -min 1.0 -max 1.5  .b  axis  configure  y
       -min  12.0 -max 55.15 To zoom interactively, you link theaxis configure
       operations with some user interaction (such as pressing the mouse  but-
       ton),  using  the  bind  command.   To convert between screen and graph
       coordinates, use the invtransform operation.  # Click the button to set
       a new minimum bind .b <ButtonPress-1> {
           %W axis configure x -min [%W axis invtransform x %x]
           %W  axis configure x -min [%W axis invtransform x %y] } By default,
       the limits of the axis are determined from data values.  To reset  back
       to  the  default  limits,  set  the  -min and -max options to the empty
       value.  # Reset the axes to autoscale again.  .b axis configure x  -min
       {}  -max  {} .b axis configure y -min {} -max {} By default, the legend
       is drawn in the right margin.  You can change this or any  legend  con-
       figuration  options using the legend component.  # Configure the legend
       font, color, and relief .b  legend  configure  -position  left  -relief
       raised  \       -font  fixed  -fg blue To prevent the legend from being
       displayed, turn on the -hide option.  # Don't display the  legend.   .b
       legend  configure  -hide yes The barchart has simple drawing procedures
       called markers.  They can be used to highlight or annotate data in  the
       graph.  The types of markers available are bitmaps, polygons, lines, or
       windows.  Markers can be used, for example, to mark  or  brush  points.
       For  example  there may be a line marker which indicates some low-water
       chart into file "file.ps" .b postscript  output  file.ps  -maxpect  yes
       -decorations  no  This generates a file file.ps containing the encapsu-
       lated PostScript of the graph.  The option -maxpect says to  scale  the
       plot  to  the  size  of  the page.  Turning off the -decorations option
       denotes that no borders or color backgrounds should be drawn (i.e.  the
       background of the margins, legend, and plotting area will be white).


SYNTAX

       barchart pathName ?option value?...  The barchart command creates a new
       window pathName and makes it into a barchart widget.  At the time  this
       command  is  invoked, there must not exist a window named pathName, but
       pathName's parent must exist.  Additional options may may be  specified
       on  the  command line or in the option database to configure aspects of
       the bar chart such as its colors and font.  See the configure operation
       below  for  the  exact  details  as  to what option and value pairs are
       valid.

       If successful, barchart returns pathName. It also  creates  a  new  Tcl
       command  pathName.   This  command may be used to invoke various opera-
       tions to query or modify the bar chart.  It has the general form: path-
       Name operation ?arg?...  Both operation and its arguments determine the
       exact behavior of the command.  The operations available  for  the  bar
       chart are described in the following section.


BARCHART OPERATIONS

       pathName bar elemName ?option value?...
              Creates  a  new  barchart element elemName.  It's an error if an
              element elemName already exists.  See the  manual  for  barchart
              for details about what option and value pairs are valid.

       pathName cget option
              Returns  the  current value of the configuration option given by
              option.  Option may be any option described below for  the  con-
              figure operation.

       pathName configure ?option value?...
              Queries  or modifies the configuration options of the graph.  If
              option isn't specified, a list describing  the  current  options
              for  pathName  is  returned.   If  option  is specified, but not
              value, then a list describing option is  returned.   If  one  or
              more  option  and value pairs are specified, then for each pair,
              the option option is set to value.  The  following  options  are
              valid.

              -background color
                     Sets  the background color. This includes the margins and
                     legend, but not the plotting area.

              -barmode mode
                     Indicates  how  related  bar  elements  will  be   drawn.
                     Related elements have data points with the same abscissas
                     (X-coordinates). Mode indicates how those segments should

              -barwidth value
                     Specifies the width of the bars.  This value can be over-
                     rided  by  the  individual elements using their -barwidth
                     configuration option.  Value is the  width  in  terms  of
                     graph-coordinates.  The default width is 1.0.

              -borderwidth pixels
                     Sets  the width of the 3-D border around the outside edge
                     of the widget.  The -relief option determines if the bor-
                     der is to be drawn.  The default is 2.

              -bottommargin pixels
                     Specifies  the  size of the margin below the X-coordinate
                     axis.  If pixels is 0, the size of the margin is selected
                     automatically.  The default is 0.

              -bufferelements boolean
                     Indicates  whether  an internal pixmap to buffer the dis-
                     play of data elements should  be  used.   If  boolean  is
                     true,  data  elements  are  drawn  to an internal pixmap.
                     This option  is  especially  useful  when  the  graph  is
                     redrawn  frequently while the remains data unchanged (for
                     example, moving a marker across the plot).  See the SPEED
                     TIPS section.  The default is 1.

              -cursor cursor
                     Specifies  the  widget's  cursor.   The default cursor is
                     crosshair.

              -font fontName
                     Specifies the font of the graph  title.  The  default  is
                     *-Helvetica-Bold-R-Normal-*-18-180-*.

              -halo pixels
                     Specifies  a  maximum distance to consider when searching
                     for the closest data point  (see  the  element's  closest
                     operation  below).   Data points further than pixels away
                     are ignored.  The default is 0.5i.

              -height pixels
                     Specifies the requested height of widget.  The default is
                     4i.

              -invertxy boolean
                     Indicates  whether the placement X-axis and Y-axis should
                     be inverted.  If boolean is true, the X and  Y  axes  are
                     swapped.  The default is 0.

              -justify justify
                     Specifies  how  the title should be justified.  This mat-
                     ters only when the title contains more than one  line  of
                     area.  The -plotrelief option determines if a  border  is
                     drawn.  The default is 2.

              -plotpadx pad
                     Sets  the  amount  of padding to be added to the left and
                     right sides of the plotting area.  Pad can be a  list  of
                     one  or  two  screen distances.  If pad has two elements,
                     the left side of the plotting area entry is padded by the
                     first  distance and the right side by the second.  If pad
                     is just one distance, both the left and right  sides  are
                     padded evenly.  The default is 8.

              -plotpady pad
                     Sets  the  amount  of  padding to be added to the top and
                     bottom of the plotting area.  Pad can be a list of one or
                     two  screen  distances.  If pad has two elements, the top
                     of the plotting area is padded by the first distance  and
                     the  bottom  by the second.  If pad is just one distance,
                     both the top and bottom are padded evenly.   The  default
                     is 8.

              -plotrelief relief
                     Specifies  the  3-D effect for the plotting area.  Relief
                     specifies how the interior of the  plotting  area  should
                     appear relative to rest of the graph; for example, raised
                     means the plot should appear to protrude from the  graph,
                     relative  to  the  surface  of the graph.  The default is
                     sunken.

              -relief relief
                     Specifies the 3-D effect for the barchart widget.  Relief
                     specifies  how the graph should appear relative to widget
                     it is packed into; for example, raised  means  the  graph
                     should appear to protrude.  The default is flat.

              -rightmargin pixels
                     Sets  the  size  of  margin from the plotting area to the
                     right edge of the window.   By  default,  the  legend  is
                     drawn  in  this  margin.  If pixels is than 1, the margin
                     size is selected automatically.

              -takefocus focus
                     Provides information used when moving the focus from win-
                     dow  to  window  via  keyboard  traversal  (e.g., Tab and
                     Shift-Tab).  If focus is 0, this means that  this  window
                     should  be skipped entirely during keyboard traversal.  1
                     means that the this  window  should  always  receive  the
                     input  focus.   An  empty  value means that the traversal
                     scripts make the decision whether to focus on the window.
                     The default is "".

              -tile image
              -width pixels
                     Specifies the requested width of the widget.  The default
                     is 5i.

       pathName crosshairs operation ?arg?
              See the CROSSHAIRS COMPONENT section.

       pathName element operation ?arg?...
              See the ELEMENT COMPONENTS section.

       pathName extents item
              Returns  the  size of a particular item in the graph.  Item must
              be  either  leftmargin,  rightmargin,  topmargin,  bottommargin,
              plotwidth, or plotheight.

       pathName grid operation ?arg?...
              See the GRID COMPONENT section.

       pathName invtransform winX winY
              Performs  an  inverse  coordinate transformation, mapping window
              coordinates back to graph-coordinates, using the standard X-axis
              and  Y-axis.  Returns a list of containing the X-Y graph-coordi-
              nates.

       pathName inside x y
              Returns 1 is the  designated  screen-coordinate  (x  and  y)  is
              inside the plotting area and 0 otherwise.

       pathName legend operation ?arg?...
              See the LEGEND COMPONENT section.

       pathName line operation arg...
              The operation is the same as element.

       pathName marker operation ?arg?...
              See the MARKER COMPONENTS section.

       pathName metafile ?fileName?
              This  operation is for Window platforms only.  Creates a Windows
              enhanced metafile of the barchart.  If present, fileName is  the
              file name of the new metafile.  Otherwise, the metafile is auto-
              matically added to the clipboard.

       pathName postscript operation ?arg?...
              See the POSTSCRIPT COMPONENT section.

       pathName snap photoName
              Takes a snapshot of the graph and stores  the  contents  in  the
              photo  image  photoName.   PhotoName  is  the name of a Tk photo
              image that must already exist.

       pathName transform x y
       A graph is composed of several components: coordinate axes,  data  ele-
       ments,  legend,  grid, cross hairs, postscript, and annotation markers.
       Instead of one big set of configuration  options  and  operations,  the
       graph  is  partitioned,  where each component has its own configuration
       options and operations that specifically control that aspect or part of
       the graph.

   AXIS COMPONENTS
       Four  coordinate  axes are automatically created: two X-coordinate axes
       (x and x2) and two Y-coordinate axes (y, and y2).  By default, the axis
       x  is located in the bottom margin, y in the left margin, x2 in the top
       margin, and y2 in the right margin.

       An axis consists of the axis line, title, major and  minor  ticks,  and
       tick  labels.   Major  ticks  are  drawn at uniform intervals along the
       axis.  Each tick is labeled with its coordinate value.  Minor ticks are
       drawn at uniform intervals within major ticks.

       The  range  of  the axis controls what region of data is plotted.  Data
       points outside the minimum and maximum limits of the axis are not plot-
       ted.   By  default,  the minimum and maximum limits are determined from
       the data, but you can reset either limit.

       You can create and use several axes. To create an axis, invoke the axis
       component  and  its create operation.  # Create a new axis called "tem-
       perature" .b axis create temperature You map data elements to  an  axis
       using the element's -mapy and -mapx configuration options. They specify
       the coordinate axes an element is mapped onto.  # Now map the  tempera-
       ture  data  to  this  axis.   .b element create "temp" -xdata $x -ydata
       $tempData \
           -mapy temperature While you can have many axes, only four axes  can
       be  displayed  simultaneously.   They  are drawn in each of the margins
       surrounding the plotting area.  The axes x and y are drawn in the  bot-
       tom  and  left  margins.  The axes x2 and y2 are drawn in top and right
       margins.  Only x and y are shown by default. Note  that  the  axes  can
       have different scales.

       To  display  a  different  axis, you invoke one of the following compo-
       nents: xaxis, yaxis, x2axis, and y2axis.  The use operation  designates
       the  axis to be drawn in the corresponding margin: xaxis in the bottom,
       yaxis in the left, x2axis in the top, and y2axis in the right.  #  Dis-
       play the axis temperature in the left margin.  .b yaxis use temperature

       You can configure axes in many ways. The axis scale can  be  linear  or
       logarithmic.   The  values  along  the  axis  can  either monotonically
       increase or decrease.  If you need custom tick labels, you can  specify
       a  Tcl procedure to format the label any way you wish.  You can control
       how ticks are drawn, by changing the major tick interval or the  number
       of minor ticks.  You can define non-uniform tick intervals, such as for
       time-series plots.


              -autorange range
                     Sets the range of values for the axis to range.  The axis
                     limits are automatically reset to display the most recent
                     data points in this range.  If range is 0.0, the range is
                     determined  from the limits of the data.  If -min or -max
                     are specified, they override this option.  The default is
                     0.0.

              -color color
                     Sets  the color of the axis and tick labels.  The default
                     is black.

              -command prefix
                     Specifies a Tcl command to be invoked when formatting the
                     axis  tick labels. Prefix is a string containing the name
                     of a Tcl proc and any extra arguments for the  procedure.
                     This  command is invoked for each major tick on the axis.
                     Two additional arguments are passed to the procedure: the
                     pathname  of the widget and the current the numeric value
                     of the tick.  The procedure returns  the  formatted  tick
                     label.   If  "" is returned, no label will appear next to
                     the tick.  You can get the standard tick labels again  by
                     setting prefix to "".  The default is "".

                     Please  note that this procedure is invoked while the bar
                     chart is redrawn.  You may query the widget's  configura-
                     tion options.  But do not reset options, because this can
                     have unexpected results.

              -descending boolean
                     Indicates whether the values along the axis are monotoni-
                     cally  increasing or decreasing.  If boolean is true, the
                     axis values will be decreasing.  The default is 0.

              -hide boolean
                     Indicates whether the axis is displayed.

              -justify justify
                     Specifies how the axis title should be  justified.   This
                     matters  only  when the axis title contains more than one
                     line of text. Justify must be  left,  right,  or  center.
                     The default is center.

              -limits formatStr
                     Specifies a printf-like description to format the minimum
                     and maximum limits of the axis.  The limits are displayed
                     at  the  top/bottom  or  left/right sides of the plotting
                     area.  FormatStr is a list of one or two format  descrip-
                     tions.   If one description is supplied, both the minimum
                     and maximum limits are formatted in  the  same  way.   If
                     two,  the  first  designates  the  format for the minimum
                     limit, the second for the maximum.  If  ""  is  given  as
                     data points tightly, at the  outermost  data  points,  or
                     loosely,  at  the outer tick intervals.  This is relevant
                     only when the axis limit is automatically calculated.  If
                     boolean  is true, the axis range is "loose".  The default
                     is 0.

              -majorticks majorList
                     Specifies where to display major axis ticks.  You can use
                     this  option  to  display ticks at non-uniform intervals.
                     MajorList is a list of axis coordinates  designating  the
                     location  of  major ticks.  No minor ticks are drawn.  If
                     majorList is "", major ticks will be  automatically  com-
                     puted. The default is "".

              -max value
                     Sets  the  maximum  limit  of  axisName.   Any data point
                     greater than value is not displayed.  If value is "", the
                     maximum limit is calculated using the largest data value.
                     The default is "".

              -min value
                     Sets the minimum limit of axisName. Any data  point  less
                     than value is not displayed.  If value is "", the minimum
                     limit is calculated using the smallest data  value.   The
                     default is "".

              -minorticks minorList
                     Specifies where to display minor axis ticks.  You can use
                     this option to display minor ticks at non-uniform  inter-
                     vals.  MinorList  is  a list of real values, ranging from
                     0.0 to 1.0, designating the placement of  a  minor  tick.
                     No minor ticks are drawn if the -majortick option is also
                     set.  If minorList is "", minor ticks will  be  automati-
                     cally computed. The default is "".

              -rotate theta
                     Specifies  the  how  many degrees to rotate the axis tick
                     labels.  Theta is a real value representing the number of
                     degrees  to  rotate  the tick labels.  The default is 0.0
                     degrees.

              -shiftby value
                     Specifies how much to automatically shift  the  range  of
                     the  axis.   When  the  new data exceeds the current axis
                     maximum, the maximum is increased in increments of value.
                     You  can  use this option to prevent the axis limits from
                     being recomputed at each new time point. If value is 0.0,
                     then no automatic shifting is down. The default is 0.0.

              -showticks boolean
                     Indicates  whether axis ticks should be drawn. If boolean
                     is true, ticks are drawn.  If false, only the  axis  line

              -tickfont fontName
                     Specifies  the  font for axis tick labels. The default is
                     *-Courier-Bold-R-Normal-*-100-*.

              -ticklength pixels
                     Sets the length of major and minor ticks (minor ticks are
                     half  the  length of major ticks). If pixels is less than
                     zero, the axis will be inverted with ticks drawn pointing
                     towards the plot.  The default is 0.1i.

              -title text
                     Sets  the title of the axis. If text is "", no axis title
                     will be displayed.

              -titlecolor color
                     Sets the color of the axis title. The default is black.

              -titlefont fontName
                     Specifies the font for axis title. The default is  *-Hel-
                     vetica-Bold-R-Normal-*-14-140-*.

              Axis configuration options may be also be set by the option com-
              mand.  The resource class is Axis.  The resource names  are  the
              names  of  the  axes  (such  as  x  or  x2).   option  add *Bar-
              chart.Axis.Color  blue  option  add  *Barchart.x.LogScale   true
              option add *Barchart.x2.LogScale false

       pathName axis create axisName ?option value?...
              Creates  a  new  axis by the name axisName.  No axis by the same
              name can already exist. Option and value are described in  above
              in the axis configure operation.

       pathName axis delete ?axisName?...
              Deletes  the  named axes. An axis is not really deleted until it
              is not longer in use, so it's safe to delete axes mapped to ele-
              ments.

       pathName axis invtransform axisName value
              Performs the inverse transformation, changing the screen-coordi-
              nate value to a graph-coordinate, mapping the  value  mapped  to
              axisName.  Returns the graph-coordinate.

       pathName axis limits axisName
              Returns  a  list of the minimum and maximum limits for axisName.
              The order of the list is min max.

       pathName axis names ?pattern?...
              Returns a list of axes matching zero or more  patterns.   If  no
              pattern argument is give, the names of all axes are returned.

       pathName axis transform axisName value
              Transforms  the  coordinate value to a screen-coordinate by map-

       right Y-axis.

       They implicitly control the axis that is currently using to that  loca-
       tion.  By default, xaxis uses the x axis, yaxis uses y, x2axis uses x2,
       and y2axis uses y2.  These components can be  more  convenient  to  use
       than  always  determining  what axes are current being displayed by the
       graph.

       The following operations are available for axes.  They  mirror  exactly
       the operations of the axis component.  The axis argument must be xaxis,
       x2axis, yaxis, or y2axis.

       pathName axis cget option

       pathName axis configure ?option value?...

       pathName axis invtransform value

       pathName axis limits

       pathName axis transform value

       pathName axis use ?axisName?
              Designates the axis axisName is to be displayed  at  this  loca-
              tion.   AxisName  can not be already in use at another location.
              This command returns the name of the axis currently  using  this
              location.

   CROSSHAIRS COMPONENT
       Cross  hairs  consist  of  two intersecting lines (one vertical and one
       horizontal) drawn completely across the plotting area.  They  are  used
       to  position the mouse in relation to the coordinate axes.  Cross hairs
       differ from line markers in that they are implemented using XOR drawing
       primitives.  This means that they can be quickly drawn and erased with-
       out redrawing the entire widget.

       The following operations are available for cross hairs:

       pathName crosshairs cget option
              Returns the current  value  of  the  cross  hairs  configuration
              option  given  by  option.   Option  may be any option described
              below for the cross hairs configure operation.

       pathName crosshairs configure ?option value?...
              Queries or modifies  the  configuration  options  of  the  cross
              hairs.   If  option  isn't  specified, a list describing all the
              current options for the cross hairs is returned.  If  option  is
              specified,  but  not  value,  then  a  list describing option is
              returned.  If one or more option and value pairs are  specified,
              then  for  each  pair,  the  cross hairs option option is set to
              value.  The following options are available for cross hairs.

              -linewidth pixels
                     Set the width of the cross hair lines.  The default is 1.

              -position pos
                     Specifies  the  screen  position  where  the  cross hairs
                     intersect.  Pos must be in the form "@x,y", where x and y
                     are the window coordinates of the intersection.

              Cross  hairs  configuration  options  may  be also be set by the
              option command.  The resource name and class are crosshairs  and
              Crosshairs       respectively.        option      add      *Bar-
              chart.Crosshairs.LineWidth     2      option      add      *Bar-
              chart.Crosshairs.Color     red

       pathName crosshairs off
              Turns off the cross hairs.

       pathName crosshairs on
              Turns on the display of the cross hairs.

       pathName crosshairs toggle
              Toggles  the  current state of the cross hairs, alternately map-
              ping and unmapping the cross hairs.


ELEMENTS

       A data element represents a set of data.  It contains x and  y  vectors
       which  are  the coordinates of the data points.  Elements are displayed
       as bars where the length of the bar is proportional to the ordinate  of
       the data point.  Elements also control the appearance of the data, such
       as the color, stipple, relief, etc.

       When new data elements are created, they are automatically added  to  a
       list  of  displayed elements.   The display list controls what elements
       are drawn and in what order.

       The following operations are available for elements.

       pathName element activate elemName ?index?...
              Specifies the data points of element elemName to be drawn  using
              active  foreground  and background colors.  ElemName is the name
              of the element and index is a number representing the  index  of
              the  data  point. If no indices are present then all data points
              become active.

       pathName element bind tagName ?sequence?  ?command?
              Associates command with tagName such  that  whenever  the  event
              sequence  given by sequence occurs for an element with this tag,
              command will be invoked.  The syntax is similar to the bind com-
              mand except that it operates on graph elements, rather than wid-
              gets. See the bind manual entry for complete details on sequence
              and the substitutions performed on command before invoking it.


       pathName element closest x y ?option value?... ?elemName?...
              Finds  the data point representing the bar closest to the window
              coordinates x and y in the element elemName.   ElemName  is  the
              name  of  an  element, which must be currently displayed.  If no
              elements  are  specified,  then  all  displayed   elements   are
              searched.   It  returns  a key-value list containing the name of
              the closest element, the index of its  closest  point,  and  the
              graph-coordinates  of  the  point.  If  no data point within the
              threshold distance can be found, "" is returned.  The  following
              option-value pairs are available.

              -halo pixels
                     Specifies a threshold distance where selected data points
                     are ignored.  Pixels is a valid screen distance, such  as
                     2  or  1.2i.   If  this  option  isn't specified, then it
                     defaults to the value of the barchart's -halo option.

       pathName element configure elemName ?elemName... ?option value?...
              Queries or modifies  the  configuration  options  for  elements.
              Several  elements  can  be  modified at the same time. If option
              isn't specified, a list describing all the current  options  for
              elemName  is  returned.   If option is specified, but not value,
              then a list describing the option option is returned.  If one or
              more  option  and value pairs are specified, then for each pair,
              the element option  option  is  set  to  value.   The  following
              options are valid for elements.

              -activepen penName
                     Specifies  pen to use to draw active element.  If penName
                     is "", no active elements will be drawn.  The default  is
                     activeLine.

              -bindtags tagList
                     Specifies the binding tags for the element.  TagList is a
                     list of binding tag names.  The tags and their order will
                     determine  how events for elements.  Each tag in the list
                     matching the current event sequence  will  have  its  Tcl
                     command  executed.  Implicitly the name of the element is
                     always the first tag in the list.  The default  value  is
                     all.

              -background color
                     Sets  the  the  color of the border around each bar.  The
                     default is white.

              -barwidth value
                     Specifies the width  the  bars  drawn  for  the  element.
                     Value  is  the  width  in  X-coordinates.  If this option
                     isn't specified, the width of each bar is  the  value  of
                     the widget's -barwidth option.

                     a list of numeric expressions representing the X-Y  coor-
                     dinate pairs of each data point.

              -foreground color
                     Sets the color of the interior of the bars.

              -hide boolean
                     Indicates  whether the element is displayed.  The default
                     is no.

              -label text
                     Sets the element's label in the legend.  If text  is  "",
                     the  element  will  have  no  entry  in  the legend.  The
                     default label is the element's name.

              -mapx xAxis
                     Selects the X-axis to  map  the  element's  X-coordinates
                     onto.  XAxis must be the name of an axis.  The default is
                     x.

              -mapy yAxis
                     Selects the Y-axis to  map  the  element's  Y-coordinates
                     onto.   YAxis must be the name of an axis. The default is
                     y.

              -relief string
                     Specifies the 3-D effect desired for bars.  Relief  indi-
                     cates  how the interior of the bar should appear relative
                     to the surface of the chart; for  example,  raised  means
                     the bar should appear to protrude from the surface of the
                     plotting area.  The default is raised.

              -stipple bitmap
                     Specifies a stipple pattern with which to draw the  bars.
                     If  bitmap  is "", then the bar is drawn in a solid fash-
                     ion.

              -xdata xVector
                     Specifies the x-coordinate vector of the  data.   XVector
                     is  the name of a BLT vector or a list of numeric expres-
                     sions.

              -ydata yVector
                     Specifies the y-coordinate vector of the  data.   YVector
                     is  the name of a BLT vector or a list of numeric expres-
                     sions.

              Element configuration options may also be set by the option com-
              mand.   The  resource names  in the option database are prefixed
              by elem.  option add *Barchart.Element.background blue

       pathName element create elemName ?option value?...

       pathName element exists elemName
              Returns  1  if an element elemName currently exists and 0 other-
              wise.

       pathName element names ?pattern?...
              Returns the elements matching one or more pattern.  If  no  pat-
              tern is given, the names of all elements is returned.

       pathName element show ?nameList?
              Queries  or modifies the element display list.  The element dis-
              play list designates the  elements  drawn  and  in  what  order.
              NameList is a list of elements to be displayed in the order they
              are named.  If there is no nameList argument, the  current  dis-
              play list is returned.

       pathName element type elemName
              Returns  the type of elemName.  If the element is a bar element,
              the commands returns the  string  "bar",  otherwise  it  returns
              "line".

   GRID COMPONENT
       Grid  lines extend from the major and minor ticks of each axis horizon-
       tally or vertically across the plotting area.  The following operations
       are available for grid lines.

       pathName grid cget option
              Returns  the current value of the grid line configuration option
              given by option.  Option may be any option described  below  for
              the grid configure operation.

       pathName grid configure ?option value?...
              Queries  or  modifies  the configuration options for grid lines.
              If option isn't specified, a list  describing  all  the  current
              grid  options for pathName is returned.  If option is specified,
              but not value, then a list describing option  is  returned.   If
              one  or more option and value pairs are specified, then for each
              pair, the grid line option option is set to value.  The  follow-
              ing options are valid for grid lines.

              -color color
                     Sets  the color of the grid lines.  The default is black.

              -dashes dashList
                     Sets the dash style of the grid lines. DashList is a list
                     of  up  to  11  numbers  that  alternately  represent the
                     lengths of the dashes and gaps on the grid  lines.   Each
                     number must be between 1 and 255.  If dashList is "", the
                     grid will be solid lines.

              -hide boolean
                     Indicates whether the grid should be drawn. If boolean is

              -minor boolean
                     Indicates  whether  the  grid  lines  should be drawn for
                     minor ticks.  If boolean is true, the lines  will  appear
                     at minor tick intervals.  The default is 1.

              Grid  configuration  options  may also be set by the option com-
              mand.  The resource name and class are  grid  and  Grid  respec-
              tively.   option add *Barchart.grid.LineWidth 2 option add *Bar-
              chart.Grid.Color     black

       pathName grid off
              Turns off the display the grid lines.

       pathName grid on
              Turns on the display the grid lines.

       pathName grid toggle
              Toggles the display of the grid.

   LEGEND COMPONENT
       The legend displays a list of the data elements.  Each  entry  consists
       of the element's symbol and label.  The legend can appear in any margin
       (the default location is in the right margin).  It can  also  be  posi-
       tioned anywhere within the plotting area.

       The following operations are valid for the legend.

       pathName legend activate pattern...
              Selects  legend entries to be drawn using the active legend col-
              ors and relief.  All entries whose element names  match  pattern
              are  selected.  To be selected, the element name must match only
              one pattern.

       pathName legend bind tagName ?sequence?  ?command?
              Associates command with tagName such  that  whenever  the  event
              sequence  given  by sequence occurs for a legend entry with this
              tag, command will be invoked.  Implicitly the element  names  in
              the  entry  are tags.  The syntax is similar to the bind command
              except that it operates on legend entries, rather than  widgets.
              See  the  bind manual entry for complete details on sequence and
              the substitutions performed on command before invoking it.

              If all arguments are specified then a new  binding  is  created,
              replacing  any  existing  binding for the same sequence and tag-
              Name.  If the first character of command is + then command  aug-
              ments  an existing binding rather than replacing it.  If no com-
              mand argument is provided then the command currently  associated
              with  tagName  and  sequence (it's an error occurs if there's no
              such binding) is returned.  If both  command  and  sequence  are
              missing  then  a list of all the event sequences for which bind-
              ings have been defined for tagName.

              -activebackground color
                     Sets the background color for active legend entries.  All
                     legend  entries  marked  active  (see the legend activate
                     operation) are drawn using this background color.

              -activeborderwidth pixels
                     Sets the width of the 3-D border around the outside  edge
                     of the active legend entries.  The default is 2.

              -activeforeground color
                     Sets the foreground color for active legend entries.  All
                     legend entries marked as active (see the legend  activate
                     operation) are drawn using this foreground color.

              -activerelief relief
                     Specifies  the  3-D  effect  desired  for  active  legend
                     entries.  Relief denotes how the interior  of  the  entry
                     should appear relative to the legend; for example, raised
                     means the entry should appear to protrude from  the  leg-
                     end,  relative to the surface of the legend.  The default
                     is flat.

              -anchor anchor
                     Tells how to position the legend relative  to  the  posi-
                     tioning  point  for the legend.  This is dependent on the
                     value of the -position option.  The default is center.

                     left or right
                                 The anchor describes how to position the leg-
                                 end vertically.

                     top or bottom
                                 The anchor describes how to position the leg-
                                 end horizontally.

                     @x,y        The anchor specifies how to position the leg-
                                 end  relative  to  the positioning point. For
                                 example, if anchor is center then the  legend
                                 is centered on the point; if anchor is n then
                                 the legend will be drawn such  that  the  top
                                 center  point of the rectangular region occu-
                                 pied by the legend will be at the positioning
                                 point.

                     plotarea    The anchor specifies how to position the leg-
                                 end relative to the plotting area. For  exam-
                                 ple,  if  anchor is center then the legend is
                                 centered in the plotting area; if  anchor  is
                                 ne  then  the  legend will be drawn such that
                                 occupies the upper right corner of the  plot-
                                 ting area.

                     of  the legend (if such border is being drawn; the relief
                     option determines this).  The default is 2 pixels.

              -font fontName
                     FontName specifies a font to use when drawing the  labels
                     of  each  element into the legend.  The default is *-Hel-
                     vetica-Bold-R-Normal-*-12-120-*.

              -foreground color
                     Sets the foreground color of the text drawn for the  ele-
                     ment's label.  The default is black.

              -hide boolean
                     Indicates  whether  the  legend  should  be displayed. If
                     boolean is true,  the  legend  will  not  be  draw.   The
                     default is no.

              -ipadx pad
                     Sets  the  amount  of internal padding to be added to the
                     width of each legend entry.  Pad can be a list of one  or
                     two  screen distances.  If pad has two elements, the left
                     side of the legend entry is padded by the first  distance
                     and  the  right  side  by the second.  If pad is just one
                     distance, both  the  left  and  right  sides  are  padded
                     evenly.  The default is 2.

              -ipady pad
                     Sets  an  amount  of  internal padding to be added to the
                     height of each legend entry.  Pad can be a list of one or
                     two  screen  distances.  If pad has two elements, the top
                     of the entry is padded by the first distance and the bot-
                     tom by the second.  If pad is just one distance, both the
                     top and bottom of  the  entry  are  padded  evenly.   The
                     default is 2.

              -padx pad
                     Sets  the  padding to the left and right exteriors of the
                     legend.  Pad can be a list of  one  or  two  screen  dis-
                     tances.   If  pad  has two elements, the left side of the
                     legend is padded by the first distance and the right side
                     by  the  second.   If pad has just one distance, both the
                     left and right sides are padded evenly.  The  default  is
                     4.

              -pady pad
                     Sets  the padding above and below the legend.  Pad can be
                     a list of one or two screen distances.  If  pad  has  two
                     elements,  the  area  above  the  legend is padded by the
                     first distance and the area below by the second.  If  pad
                     is  just  one distance, both the top and bottom areas are
                     padded evenly.  The default is 0.

                     drawn on top of any elements that  may  overlap  it.  The
                     default is no.

              -relief relief
                     Specifies  the  3-D effect for the border around the leg-
                     end.  Relief specifies how the  interior  of  the  legend
                     should  appear  relative  to  the bar chart; for example,
                     raised means the legend should appear  to  protrude  from
                     the  bar chart, relative to the surface of the bar chart.
                     The default is sunken.

              Legend configuration options may also be set by the option  com-
              mand.  The resource name and class are legend and Legend respec-
              tively.  option add *Barchart.legend.Foreground blue option  add
              *Barchart.Legend.Relief     raised

       pathName legend deactivate pattern...
              Selects  legend entries to be drawn using the normal legend col-
              ors and relief.  All entries whose element names  match  pattern
              are  selected.  To be selected, the element name must match only
              one pattern.

       pathName legend get pos
              Returns the name of the element whose entry  is  at  the  screen
              position  pos  in  the  legend.  Pos must be in the form "@x,y",
              where x and y are window coordinates.  If the given  coordinates
              do not lie over a legend entry, "" is returned.

   PEN COMPONENTS
       Pens  define  attributes  for  elements.  Pens mirror the configuration
       options of data elements that pertain to  how  symbols  and  lines  are
       drawn.  Data elements use pens to determine how they are drawn.  A data
       element may use several pens at once.  In this case, the pen used for a
       particular  data  point is determined from each element's weight vector
       (see the element's -weight and -style options).

       One pen, called activeBar, is automatically created.  It's used as  the
       default  active  pen  for  elements.  So  you  can  change  the  active
       attributes for all elements by simply reconfiguring this pen.   .g  pen
       configure  "activeBar" -fg green -bg green4 You can create and use sev-
       eral pens. To create a pen, invoke the pen  component  and  its  create
       operation.   .g  pen  create myPen You map pens to a data element using
       either the element's -pen or -activepen  options.   .g  element  create
       "e1" -xdata $x -ydata $tempData \
           -pen myPen An element can use several pens at once. This is done by
       specifying the name of the pen in the element's  style  list  (see  the
       -styles  option).   .g element configure "e1" -styles { myPen 2.0 3.0 }
       This says that any data point with a weight between 2.0 and 3.0  is  to
       be drawn using the pen myPen.  All other points are drawn with the ele-
       ment's default attributes.

       The following operations are available for pen components.
              value.  The following options are valid for pens.

              -background color
                     Sets the the color of the border around  each  bar.   The
                     default is white.

              -borderwidth pixels
                     Sets  the border width of the 3-D border drawn around the
                     outside of each bar.  The -relief  option  determines  if
                     such  a  border  is drawn.  Pixels must be a valid screen
                     distance like 2 or 0.25i. The default is 2.

              -foreground color
                     Sets the color of the interior of the bars.

              -relief string
                     Specifies the 3-D effect desired for bars.  Relief  indi-
                     cates  how the interior of the bar should appear relative
                     to the surface of the chart; for  example,  raised  means
                     the  bar  should  appear  to protrude from the bar chart,
                     relative to  the  surface  of  the  plotting  area.   The
                     default is raised.

              -stipple bitmap
                     Specifies  a stipple pattern with which to draw the bars.
                     If bitmap is "", then the bar is drawn in a  solid  fash-
                     ion.

              -type elemType
                     Specifies the type of element the pen is to be used with.
                     This option should only be  employed  when  creating  the
                     pen.   This is for those that wish to mix different types
                     of elements (bars and lines)  on  the  same  graph.   The
                     default type is "bar".

              Pen  configuration options may be also be set by the option com-
              mand.  The resource class is Pen.  The resource  names  are  the
              names  of  the  pens.   option add *Barchart.Pen.Foreground
              blue option add *Barchart.activeBar.foreground  green

       pathName pen create penName ?option value?...
              Creates a new pen by the name penName.  No pen by the same  name
              can  already  exist.  Option and value are described in above in
              the pen configure operation.

       pathName pen delete ?penName?...
              Deletes the named pens. A pen is not really deleted until it  is
              not  longer  in  use, so it's safe to delete pens mapped to ele-
              ments.

       pathName pen names ?pattern?...
              Returns a list of pens matching zero or more  patterns.   If  no
              option.   Option may be any option described below for the post-
              script configure operation.

       pathName postscript configure ?option value?...
              Queries or modifies the  configuration  options  for  PostScript
              generation.   If  option  isn't specified, a list describing the
              current postscript options for pathName is returned.  If  option
              is  specified,  but  not value, then a list describing option is
              returned.  If one or more option and value pairs are  specified,
              then  for  each  pair,  the  postscript  option option is set to
              value.  The following postscript options are available.

              -center boolean
                     Indicates whether the plot  should  be  centered  on  the
                     PostScript  page.   If boolean is false, the plot will be
                     placed in the upper left corner of the page.  The default
                     is 1.

              -colormap varName
                     VarName  must be the name of a global array variable that
                     specifies a color mapping from the X color name to  Post-
                     Script.   Each  element  of varName must consist of Post-
                     Script code to set a particular color value  (e.g.  ``1.0
                     1.0  0.0  setrgbcolor'').  When generating color informa-
                     tion in PostScript, the array variable varName is checked
                     if  an element of the name as the color exists. If so, it
                     uses its value as  the  PostScript  command  to  set  the
                     color.  If this option hasn't been specified, or if there
                     isn't an entry in varName for a given color, then it uses
                     the red, green, and blue intensities from the X color.

              -colormode mode
                     Specifies  how to output color information.  Mode must be
                     either color (for full color output), gray  (convert  all
                     colors  to their gray-scale equivalents) or mono (convert
                     foreground colors  to  black  and  background  colors  to
                     white).  The default mode is color.

              -fontmap varName
                     VarName  must be the name of a global array variable that
                     specifies a font mapping from the X font  name  to  Post-
                     Script.   Each  element  of varName must consist of a Tcl
                     list with one or two elements; the name and point size of
                     a  PostScript  font.  When outputting PostScript commands
                     for a particular font,  the  array  variable  varName  is
                     checked  to  see  if  an  element  by  the specified font
                     exists.  If there is  such  an  element,  then  the  font
                     information  contained  in  that  element  is used in the
                     PostScript output.  (If the point size  is  omitted  from
                     the  list, the point size of the X font is used).  Other-
                     wise the X font is examined in an attempt to  guess  what
                     PostScript  font to use.  This works only for fonts whose
                     widget's height.  The default is 0.

              -landscape boolean
                     If boolean is true, this specifies the printed area is to
                     be  rotated 90 degrees.  In non-rotated output the X-axis
                     of the printed area runs along the short dimension of the
                     page  (``portrait''  orientation);  in rotated output the
                     X-axis runs along the long dimension of the page (``land-
                     scape'' orientation).  Defaults to 0.

              -maxpect boolean
                     Indicates  to  scale  the plot so that it fills the Post-
                     Script page.  The aspect ratio of the barchart  is  still
                     retained.  The default is 0.

              -padx pad
                     Sets  the  horizontal padding for the left and right page
                     borders.  The borders are exterior to the plot.  Pad  can
                     be a list of one or two screen distances.  If pad has two
                     elements, the left border is padded by the first distance
                     and  the right border by the second.  If pad has just one
                     distance, both the left  and  right  borders  are  padded
                     evenly.  The default is 1i.

              -pady pad
                     Sets  the  vertical  padding  for the top and bottom page
                     borders. The borders are exterior to the plot.   Pad  can
                     be a list of one or two screen distances.  If pad has two
                     elements, the top border is padded by the first  distance
                     and the bottom border by the second.  If pad has just one
                     distance, both the top  and  bottom  borders  are  padded
                     evenly.  The default is 1i.

              -paperheight pixels
                     Sets the height of the postscript page.  This can be used
                     to select between different page sizes (letter, A4, etc).
                     The default height is 11.0i.

              -paperwidth pixels
                     Sets  the width of the postscript page.  This can be used
                     to select between different page sizes (letter, A4, etc).
                     The default width is 8.5i.

              -width pixels
                     Sets  the  width  of  the plot.  This lets you generate a
                     plot of a width different from that of  the  widget.   If
                     pixels is 0, the width is the same as the widget's width.
                     The default is 0.

              Postscript configuration options may  be  also  be  set  by  the
              option  command.  The resource name and class are postscript and
              Postscript respectively.  option add  *Barchart.postscript.Deco-

       with  a  particular  element, so that when the element is hidden or un-
       hidden, so is the marker.  By  default,  markers  are  the  last  items
       drawn,  so  that  data  elements  will  appear in behind them.  You can
       change this by configuring the -under option.

       Markers, in contrast to elements, don't affect the scaling of the coor-
       dinate axes.  They can also have elastic coordinates (specified by -Inf
       and Inf respectively) that translate into the minimum or maximum  limit
       of  the axis.  For example, you can place a marker so it always remains
       in the lower left corner of the plotting area, by using the coordinates
       -Inf,-Inf.

       The following operations are available for markers.

       pathName marker after markerId ?afterId?
              Changes the order of the markers, drawing the first marker after
              the second.  If no second afterId  argument  is  specified,  the
              marker  is  placed at the end of the display list.  This command
              can be used to control how markers are displayed  since  markers
              are drawn in the order of this display list.

       pathName marker before markerId ?beforeId?
              Changes  the  order  of  the  markers,  drawing the first marker
              before the second.  If no second beforeId argument is specified,
              the marker is placed at the beginning of the display list.  This
              command can be used to control how markers are  displayed  since
              markers are drawn in the order of this display list.

       pathName marker bind tagName ?sequence?  ?command?
              Associates  command  with  tagName  such that whenever the event
              sequence given by sequence occurs for a marker  with  this  tag,
              command will be invoked.  The syntax is similar to the bind com-
              mand except that it operates on graph markers, rather than  wid-
              gets. See the bind manual entry for complete details on sequence
              and the substitutions performed on command before invoking it.

              If all arguments are specified then a new  binding  is  created,
              replacing  any  existing  binding for the same sequence and tag-
              Name.  If the first character of command is + then command  aug-
              ments  an existing binding rather than replacing it.  If no com-
              mand argument is provided then the command currently  associated
              with  tagName  and  sequence (it's an error occurs if there's no
              such binding) is returned.  If both  command  and  sequence  are
              missing  then  a list of all the event sequences for which bind-
              ings have been defined for tagName.

       pathName marker cget option
              Returns the current value of  the  marker  configuration  option
              given  by  option.   Option may be any option described below in
              the configure operation.

       pathName marker configure markerId ?option value?...
                     determine  how  events for markers are handled.  Each tag
                     in the list matching the current event sequence will have
                     its  Tcl  command  executed.   Implicitly the name of the
                     marker is always the first tag in the list.  The  default
                     value is all.

              -coords coordList
                     Specifies  the coordinates of the marker.  CoordList is a
                     list of graph-coordinates.   The  number  of  coordinates
                     required  is  dependent  on  the  type  of marker.  Text,
                     image, and window markers need only two  coordinates  (an
                     X-Y  coordinate).   Bitmap markers can take either two or
                     four coordinates (if four, they represent the corners  of
                     the bitmap). Line markers need at least four coordinates,
                     polygons at least six.  If coordList is  "",  the  marker
                     will not be displayed.  The default is "".

              -element elemName
                     Links  the  marker with the element elemName.  The marker
                     is drawn only if the element is also currently  displayed
                     (see  the  element's show operation).  If elemName is "",
                     the marker is always drawn.  The default is "".

              -hide boolean
                     Indicates whether the marker  is  drawn.  If  boolean  is
                     true, the marker is not drawn.  The default is no.

              -mapx xAxis
                     Specifies  the  X-axis  to map the marker's X-coordinates
                     onto.  XAxis must the name of an axis.  The default is x.

              -mapy yAxis
                     Specifies  the  Y-axis  to map the marker's Y-coordinates
                     onto.  YAxis must the name of an axis.  The default is y.

              -name markerId
                     Changes  the  identifier  for the marker.  The identifier
                     markerId can not already be used by another  marker.   If
                     this   option  isn't  specified,  the  marker's  name  is
                     uniquely generated.

              -under boolean
                     Indicates whether the marker is  drawn  below/above  data
                     elements.   If  boolean  is  true, the marker is be drawn
                     underneath the data elements.  Otherwise, the  marker  is
                     drawn on top of the element.  The default is 0.

              -xoffset pixels
                     Specifies a screen distance to offset the marker horizon-
                     tally.  Pixels is a valid screen distance, such as  2  or
                     1.2i.  The default is 0.

              Creates  a marker of the selected type. Type may be either text,
              line, bitmap, image, polygon, or window.  This  command  returns
              the  marker  identifier,  used  as  the markerId argument in the
              other marker-related commands.  If the  -name  option  is  used,
              this  overrides  the normal marker identifier.  If the name pro-
              vided is already used for another marker, the  new  marker  will
              replace the old.

       pathName marker delete ?name?...
              Removes  one  of  more markers.  The graph will automatically be
              redrawn without the marker..

       pathName marker exists markerId
              Returns 1 if the marker markerId exists and 0 otherwise.

       pathName marker names ?pattern?
              Returns the names of all the markers that currently  exist.   If
              pattern  is  supplied,  only  those markers whose names match it
              will be returned.

       pathName marker type markerId
              Returns the type of the marker given by markerId, such  as  line
              or  text.  If markerId is not a valid a marker identifier, "" is
              returned.

   BITMAP MARKERS
       A bitmap marker displays a bitmap.  The size  of  the  bitmap  is  con-
       trolled  by  the  number of coordinates specified.  If two coordinates,
       they specify the position of the top-left corner of  the  bitmap.   The
       bitmap  retains  its normal width and height.  If four coordinates, the
       first and second pairs of coordinates represent the corners of the bit-
       map.   The bitmap will be stretched or reduced as necessary to fit into
       the bounding rectangle.

       Bitmap markers are created with the marker's create  operation  in  the
       form:  pathName  marker  create  bitmap ?option value?...  There may be
       many option-value pairs, each sets  a  configuration  options  for  the
       marker.   These  same  option-value pairs may be used with the marker's
       configure operation.

       The following options are specific to bitmap markers:

       -background color
              Same as the -fill option.

       -bitmap bitmap
              Specifies the bitmap to be displayed.   If  bitmap  is  "",  the
              marker will not be displayed.  The default is "".

       -fill color
              Sets  the background color of the bitmap.  If color is the empty
              string, no background will be transparent.   The  default  back-

       -rotate theta
              Sets  the rotation of the bitmap.  Theta is a real number repre-
              senting the angle of rotation in degrees.  The marker  is  first
              rotated  and  then placed according to its anchor position.  The
              default rotation is 0.0.

   IMAGE MARKERS
       A image marker displays an image.  Image markers are created  with  the
       marker's  create  operation  in  the form: pathName marker create image
       ?option value?...  There may be many option-value pairs,  each  sets  a
       configuration option for the marker.  These same option-value pairs may
       be used with the marker's configure operation.

       The following options are specific to image markers:

       -anchor anchor
              Anchor tells how to position the image relative to the position-
              ing  point  for the image. For example, if anchor is center then
              the image is centered on the point;  if anchor  is  n  then  the
              image  will be drawn such that the top center point of the rect-
              angular region occupied by the image will be at the  positioning
              point.  This option defaults to center.

       -image image
              Specifies  the  image  to  be drawn.  If image is "", the marker
              will not be drawn.  The default is "".

   LINE MARKERS
       A line marker displays one or more connected line segments.  Line mark-
       ers  are  created  with marker's create operation in the form: pathName
       marker create line ?option value?...  There may  be  many  option-value
       pairs,  each  sets  a  configuration option for the marker.  These same
       option-value pairs may be used with the marker's configure operation.

       The following options are specific to line markers:

       -dashes dashList
              Sets the dash style of the line. DashList is a list of up to  11
              numbers that alternately represent the lengths of the dashes and
              gaps on the line.  Each number must be between 1  and  255.   If
              dashList is "", the marker line will be solid.

       -fill color
              Sets  the background color of the line.  This color is used with
              striped lines (see the -dashes option). If color  is  the  empty
              string,  no  background color is drawn (the line will be dashed,
              not striped).  The default background color is "".

       -linewidth pixels
              Sets the width of the lines.  The default width is 0.

       in  the  form:  pathName marker create polygon ?option value?...  There
       may be many option-value pairs, each sets a  configuration  option  for
       the  marker.  These same option-value pairs may be used with the marker
       configure command to change the marker's configuration.  The  following
       options are supported for polygon markers:

       -dashes dashList
              Sets the dash style of the outline of the polygon. DashList is a
              list of up to 11 numbers that alternately represent the  lengths
              of  the  dashes  and  gaps  on the outline.  Each number must be
              between 1 and 255. If dashList is "",  the  outline  will  be  a
              solid line.

       -fill color
              Sets  the  fill  color of the polygon.  If color is "", then the
              interior of the polygon is transparent.  The default is white.

       -linewidth pixels
              Sets the width of the outline of the polygon. If pixels is zero,
              no outline is drawn. The default is 0.

       -outline color
              Sets the color of the outline of the polygon.  If the polygon is
              stippled (see the -stipple option),  then  this  represents  the
              foreground color of the stipple.  The default is black.

       -stipple bitmap
              Specifies  that the polygon should be drawn with a stippled pat-
              tern rather than a solid color. Bitmap specifies a bitmap to use
              as  the  stipple  pattern.  If bitmap is "", then the polygon is
              filled with a solid color (if the -fill  option  is  set).   The
              default is "".

   TEXT MARKERS
       A  text  marker displays a string of characters on one or more lines of
       text.  Embedded newlines cause line breaks.  They may be used to  anno-
       tate  regions  of  the graph.  Text markers are created with the create
       operation in the form: pathName marker create  text  ?option  value?...
       There  may be many option-value pairs, each sets a configuration option
       for the text marker.  These same option-value pairs may  be  used  with
       the marker's configure operation.

       The following options are specific to text markers:

       -anchor anchor
              Anchor  tells how to position the text relative to the position-
              ing point for the text. For example, if anchor  is  center  then
              the  text is centered on the point; if anchor is n then the text
              will be drawn such that the top center point of the  rectangular
              region  occupied  by  the text will be at the positioning point.
              This default is center.


       -justify justify
              Specifies  how  the text should be justified.  This matters only
              when the marker contains more than one  line  of  text.  Justify
              must be left, right, or center.  The default is center.

       -outline color
              Sets the color of the text. The default value is black.

       -padx pad
              Sets  the  padding  to the left and right exteriors of the text.
              Pad can be a list of one or two screen distances.   If  pad  has
              two  elements,  the left side of the text is padded by the first
              distance and the right side by the second.  If pad has just  one
              distance,  both the left and right sides are padded evenly.  The
              default is 4.

       -pady pad
              Sets the padding above and below the text.  Pad can be a list of
              one  or two screen distances.  If pad has two elements, the area
              above the text is padded by the  first  distance  and  the  area
              below  by the second.  If pad is just one distance, both the top
              and bottom areas are padded evenly.  The default is 4.

       -rotate theta
              Specifies the number of degrees to rotate the text.  Theta is  a
              real  number  representing the angle of rotation.  The marker is
              first rotated along its center and is then  drawn  according  to
              its anchor position. The default is 0.0.

       -text text
              Specifies  the  text  of  the marker.  The exact way the text is
              displayed may be affected by other options such  as  -anchor  or
              -rotate.

   WINDOW MARKERS
       A  window marker displays a widget at a given position.  Window markers
       are created with the marker's create operation in  the  form:  pathName
       marker  create window ?option value?...  There may be many option-value
       pairs, each sets a configuration option for  the  marker.   These  same
       option-value pairs may be used with the marker's configure command.

       The following options are specific to window markers:

       -anchor anchor
              Anchor  tells  how  to position the widget relative to the posi-
              tioning point for the widget. For example, if anchor  is  center
              then  the  widget  is centered on the point; if anchor is n then
              the widget will be displayed such that the top center  point  of
              the  rectangular  region  occupied  by the widget will be at the
              positioning point.  This option defaults to center.


GRAPH COMPONENT BINDINGS

       Specific barchart components, such  as  elements,  markers  and  legend
       entries,  can  have  a  command trigger when event occurs in them, much
       like canvas items in Tk's canvas widget.  Not all event  sequences  are
       valid.  The only binding events that may be specified are those related
       to the mouse and keyboard (such as Enter, Leave,  ButtonPress,  Motion,
       and KeyPress).

       Only  one element or marker can be picked during an event.  This means,
       that if the mouse is directly over both an element and a  marker,  only
       the  uppermost  component  is  selected.   This  isn't  true for legend
       entries.  Both a legend entry and an element (or marker)  binding  com-
       mands will be invoked if both items are picked.

       It is possible for multiple bindings to match a particular event.  This
       could occur, for example, if one binding is associated with the element
       name  and another is associated with one of the element's tags (see the
       -bindtags option).  When this occurs, all of the matching bindings  are
       invoked.   A binding associated with the element name is invoked first,
       followed by one binding for each of the element's bindtags.   If  there
       are  multiple  matching  bindings  for a single tag, then only the most
       specific binding is invoked.  A continue command in  a  binding  script
       terminates  that script, and a break command terminates that script and
       skips any remaining scripts for the event, just as for  the  bind  com-
       mand.

       The  -bindtags  option for these components controls addition tag names
       which can be matched.  Implicitly elements and markers always have tags
       matching  their  names.   Setting  the  value  of  the -bindtags option
       doesn't change this.


C LANGUAGE API

       You can manipulate data elements from the C  language.   There  may  be
       situations  where it is too expensive to translate the data values from
       ASCII strings.  Or you might want to read data in a special  file  for-
       mat.

       Data  can manipulated from the C language using BLT vectors.  You spec-
       ify the X-Y data coordinates of an element as  vectors  and  manipulate
       the  vector  from  C.  The barchart will be redrawn automatically after
       the vectors are updated.

       From Tcl, create the vectors and configure the  element  to  use  them.
       vector  X  Y  .g  element configure line1 -xdata X -ydata Y To set data
       points from C, you pass the values  as  arrays  of  doubles  using  the
       Blt_ResetVector call.  The vector is reset with the new data and at the
       next idle point (when Tk re-enters its event loop), the graph  will  be
       redrawn automatically.  #include <tcl.h> #include <blt.h>

       register int i; Blt_Vector *xVec, *yVec; double x[50], y[50];

       /*  Get  the  BLT  vectors  "X"  and "Y" (created above from Tcl) */ if
       There may be cases where the bar chart needs to be drawn and updated as
       quickly as possible.  If drawing speed becomes a big problem, here  are
       a few tips to speed up displays.

       o Try  to  minimize  the  number  of data points.  The more data points
         looked at, the more work the bar chart must do.

       o If your data is generated as floating point values, the time required
         to  convert the data values to and from ASCII strings can be signifi-
         cant, especially when there any many data points.  You can avoid  the
         redundant  string-to-decimal  conversions using the C API to BLT vec-
         tors.

       o Don't stipple or dash the element.  Solid bars are much faster.

       o If you update data elements frequently, try turning off the  widget's
         -bufferelements  option.   When  the bar chart is first displayed, it
         draws data elements into an internal pixmap.  The pixmap  acts  as  a
         cache,  so that when the bar chart needs to be redrawn again, and the
         data elements or coordinate axes haven't changed, the pixmap is  sim-
         ply  copied  to  the  screen.  This is especially useful when you are
         using markers to highlight points and regions on the bar chart.   But
         if  the  bar chart is updated frequently, changing either the element
         data or coordinate axes, the buffering becomes redundant.


LIMITATIONS

       Auto-scale routines do not use requested min/max limits  as  boundaries
       when the axis is logarithmically scaled.

       The PostScript output generated for polygons with more than 1500 points
       may exceed the limits of some printers (See PostScript Language  Refer-
       ence  Manual,  page 568).  The work-around is to break the polygon into
       separate pieces.


KEYWORDS

       bar chart, widget



BLT                               BLT_VERSION                      barchart(n)

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