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2 Ghostview interface to ghostscript
4 When the GHOSTVIEW environment variable is set, ghostscript draws on
5 an existing drawable rather than creating its own window. Ghostscript
6 can be directed to draw on either a window or a pixmap.
8 Drawing on a Window
10 The GHOSTVIEW environment variable contains the window id of the target
11 window. The window id is an integer. Ghostview will use the attributes
12 of the window to obtain the width, height, colormap, screen, and visual of
13 the window. The remainder of the information is gotten from the GHOSTVIEW
14 property on that window.
17 Drawing on a Pixmap
19 The GHOSTVIEW environment variable contains a window id and a pixmap id.
20 They are integers separated by white space. Ghostview will use the attributes
21 of the window to obtain the colormap, screen, and visual to use. The
22 remainder of the information, including the width and height of the pixmap,
23 is gotten from the GHOSTVIEW property on the window. In this case, the
24 property is deleted when read.
26 The GHOSTVIEW environment variable
28 parameters: window-id [pixmap-id]
30 scanf format: "%d %d"
32 explanation of parameters:
34 window-id: tells ghostscript where to
35 - read the GHOSTVIEW property
36 - send events
37 If pixmap-id is not present,
38 ghostscript will draw on this window.
40 pixmap-id: If present, tells ghostscript that a pixmap will be used
41 as the final destination for drawing. The window will
42 not be touched for drawing purposes.
44 The GHOSTVIEW property
46 type: STRING
50 Drawing on a window:
51 bpixmap orient llx lly urx ury xdpi ydpi [left bottom top right]
53 Drawing on a pixmap:
54 bpixmap orient llx lly urx ury xdpi ydpi left bottom top right width height
56 scanf format: "%d %d %d %d %d %d %f %f %d %d %d %d %d %d"
58 explanation of parameters:
60 bpixmap: pixmap id of the backing pixmap for the window. If no
61 pixmap is to be used, this parameter should be zero. This
62 parameter must be zero when drawing on a pixmap.
64 orient: orientation of the page. The number represents clockwise
65 rotation of the paper in degrees. Permitted values are
66 0, 90, 180, 270.
68 llx, lly, urx, ury: Bounding box of the drawable. The bounding box
69 is specified in PostScript points in default user coordinates.
71 xdpi, ydpi: Resolution of window. (This can be derived from the
72 other parameters, but not without roundoff error. These
73 values are included to avoid this error.)
75 left, bottom, top, right: (optional when drawing on a window)
76 Margins around the window. The margins extend the imageable
77 area beyond the boundaries of the window. This is primarily
78 used for popup zoom windows. I have encountered several
79 instances of PostScript program that position themselves
80 with respect to the imageable area. The margins are specified
81 in PostScript points. If omitted, the margins are assumed to
82 be 0.
84 width, height: (Only specified when drawing on Pixmap)
85 The width and height of the pixmap. (Too bad that we can't
86 just query the server.)
88 Events from ghostscript
90 If the final destination is a pixmap, the client will get a property notify
91 event when ghostscript reads the GHOSTVIEW property causing it to be deleted.
93 Ghostscript sends events to the window where it read the GHOSTVIEW property.
94 These events are of type ClientMessage. The message_type is set to
95 either PAGE or DONE. The first long data value gives the window to be used
96 to send replies to ghostscript. The second long data value gives the primary
97 drawable. If rendering to a pixmap, it is the primary drawable. If rendering
98 to a window, the backing pixmap is the primary drawable. If no backing pixmap
99 is employed, then the window is the primary drawable. This field is necessary
100 to distinguish multiple ghostscripts rendering to separate pixmaps where the
101 GHOSTVIEW property was placed on the same window.
103 The PAGE message indicates that a "page" has completed. Ghostscript will
104 wait until it receives a ClientMessage whose message_type is NEXT before
107 The DONE message indicates that ghostscript has finished processing.