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    1 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    2    - License, v. 2.0. If a copy of the MPL was not distributed with this
    3    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
    4 
    5 <!-- vim:sw=2:et:ts=2:tw=72:
    6 -->
    7 <!DOCTYPE html public "-//W3C//DTD HTML 4.01 Transitional//EN"
    8   "http://www.w3.org/TR/html4/loose.dtd">
    9 <html lang="en-US">
   10 <head>
   11   <title>Table Reflow Tech Talk, 2002-08-05</title>
   12   <style type="text/css">
   13 
   14   html, body {
   15     height: 100%;
   16     overflow: visible;
   17   }
   18 
   19   body {
   20     font-size: 1.4em;
   21     font-family: Verdana, Arial, Helvetica, sans-serif;
   22     font-weight: bold;
   23     background: white;
   24     color: black;
   25   }
   26 
   27   h1, h2, p {
   28     margin: 0;
   29   }
   30 
   31   h1 {
   32     font: inherit;
   33     font-size: 1.5em;
   34     /* text-align: center; */
   35     margin-bottom: 0.8em;
   36     border-bottom: 0.1em solid #006;
   37     color: #006;
   38   }
   39 
   40   h2 {
   41     font: inherit;
   42     font-size: 1.2em;
   43     text-align: left;
   44     margin: 0.15em 0;
   45   }
   46 
   47   ul {
   48     padding: 0 0 0 1.4em;
   49     margin: 0;
   50   }
   51 
   52   li { margin: 0; 
   53        margin-top: 0.5em; 
   54        padding: 0; 
   55        font-size: 1.0em;}
   56 
   57   div.slide {
   58     position: relative;
   59     min-height: 100%;
   60   }
   61 
   62   div.nav {
   63     /*
   64     position: absolute;
   65     top: 4px;
   66     right: 4px;
   67     */
   68     float: right;
   69     margin: 4px;
   70   }
   71 
   72   div.nav :link, div.nav :visited, div.nav span {
   73     text-decoration: none;
   74     background: #006;
   75     color: white;
   76     padding: 0 0.4em 0.2em 0.4em;
   77     line-height: 1.4em;
   78   }
   79 
   80   div.nav :link:hover, div.nav :visited:hover {
   81     background: #00f;
   82   }
   83 
   84   table {
   85     margin: auto;
   86   }
   87 
   88   table.box {
   89     border-collapse: collapse;
   90     border: 2px solid black;
   91     box-sizing: border-box;
   92     width:98%;
   93     height:96%;
   94   }
   95 
   96   row {
   97     border: 2px solid black;
   98   }
   99   row.title {
  100     border: hidden;
  101   }
  102 
  103   table td {
  104     /*text-align: center;*/
  105     empty-cells: hide;
  106   }
  107 
  108   table td.box {
  109     height:100%;
  110     border: 2px solid black;
  111   }
  112 
  113   table td.title {
  114     border-top: hidden;
  115     border-right: hidden;
  116     border-left: hidden;
  117     font-size: .5em;
  118   }
  119 
  120   table td.title2 {
  121     border-bottom: hidden;
  122     border-right: hidden;
  123     border-left: hidden;
  124     font-size: .5em;
  125   }
  126 
  127   table.tree tr:not(.arrows) td {
  128     font-family: monospace;
  129     border: 0.1em solid;
  130     font-size: .7em;
  131     text-align:center;
  132   }
  133 
  134   table td.left-arrow {
  135     text-align: right;
  136   }
  137 
  138   table td.right-arrow {
  139     text-align: left;
  140   }
  141 
  142   table td.center-arrow {
  143     text-align: center;
  144   }
  145 
  146   span.html {
  147     color:purple;
  148   }
  149 
  150   table td.space {
  151     width: 5%;
  152   }
  153 
  154   table td.frame {
  155     width: 22%;
  156   }
  157 
  158   span.comment {
  159     color: red;
  160   }
  161 
  162   </style>
  163 </head>
  164 <body>
  165 
  166 <div class="slide" id="s0">
  167   <div class="nav">
  168     <a href="#s28">&lt;</a>
  169     <a href="#s1">&gt;</a>
  170   </div>
  171   <table style="margin: auto"><tr><td>
  172   <center>
  173     <h1>Table Reflow Internals<br>Tech Talk</h1>
  174     <p>Aug 5, 2002</p>
  175     <p style="margin-top: 0.5em">Chris Karnaze</a></p>
  176   </center>
  177   </td></tr></table>
  178 
  179 </div>
  180 
  181 <div class="slide" id="s1">
  182   <div class="nav">
  183     <a href="#s0">&lt;</a>
  184     <a href="#s2">&gt;</a>
  185   </div>
  186   <h1>Overview</h1>
  187   <ul>
  188     <li>Review of reflow</li>
  189     <li>Table frames</li>
  190     <li>Table reflow</li> 
  191     <li>Intro to paginated reflow</li>
  192     <li>Table paginated reflow</li>
  193   </ul>
  194 </div>
  195 
  196 <div class="slide" id="s2">
  197   <div class="nav">
  198     <a href="#s1">&lt;</a>
  199     <a href="#s3">&gt;</a>
  200   </div>
  201   <h1>Review of Reflow</h1>
  202   <ul>
  203     <li>Reflow process starts when
  204       <ul>
  205         <li>An html document starts loading (the frame tree contains only viewport, scroll(s), canvas, html, body).</li>
  206         <li>The initial chunk of an xml doc is loaded.</li> 
  207         <li>The initial chunk of an html doc (or a subsequent chunk of an xml doc) is loaded. The container posts a 
  208         dirty reflow command with itself as the target. </li>
  209         <li>Content is inserted, appended, or deleted through the DOM. The container posts a dirty reflow command 
  210         with itself as the target.</li>
  211         <li>Style changes through the DOM - javascript, browser change font (CTRL+/-), a preference changes, etc.</li>
  212       </ul>
  213     </li>
  214   </ul>
  215 </div>
  216 
  217 <div class="slide" id="s3">
  218   <div class="nav">
  219     <a href="#s2">&lt;</a>
  220     <a href="#s4">&gt;</a>
  221   </div>
  222   <h1>Review of Reflow</h1>
  223   <ul>
  224     <li>Reflow starts with pres shell
  225       <ul>
  226         <li>Which reflows the reflow root (usually the view port frame),</li>
  227         <li>Which reflows it children, etc.</li>
  228       </ul>
  229     </li>
  230     <li>Ususally it starts when the pres shell processes its queue of reflow commands.</li>
  231     <li>The reflower
  232      <ul>
  233          <li>Positions reflowee (if it can) before actually reflowing in case views are involved 
  234          (e.g. absolutely positioned elements) </li>
  235          <li>Reflows reflowee and passes a reflow state (in) and a reflow metrics (in/out)</li> 
  236      </ul>
  237     </li>
  238   </ul>
  239 </div>
  240 
  241 <div class="slide" id="s4">
  242   <div class="nav">
  243     <a href="#s3">&lt;</a>
  244     <a href="#s5">&gt;</a>
  245   </div>
  246   <h1>Review of Reflow</h1>
  247   <ul>
  248     <li>The reflow state:
  249      <ul>
  250       <li>Is a node in a tree structurally equivalent to the frame tree of reflow participants</li>
  251       <li>contains:
  252         <ul> 
  253          <li>reflow type,</li>
  254          <li>avail size,</li> 
  255          <li>various computed values,</li>
  256          <li>resolved style structs</li>
  257          <li>possible request for preferred size and more.</li>
  258         </ul>
  259       </li> 
  260      </ul>
  261     </li>
  262    </ul>
  263 </div>
  264 
  265 <div class="slide" id="s5">
  266   <div class="nav">
  267     <a href="#s4">&lt;</a>
  268     <a href="#s6">&gt;</a>
  269   </div>
  270   <h1>Review of Reflow</h1>
  271   <ul>
  272     </li>
  273       <li>the reflow metrics contains:
  274          <ul class=nested>
  275       <li>max element size (if requested) - the minimum size it can be</li> 
  276       <li>preferred size (if requested) - the size it would like to be given no size constraints.</li> 
  277       <li>desired size - the size it would like to be given the avail size. This
  278       is equivalent to preferred size if the avail size is not constrained.</li>
  279      </ul>
  280     </li>
  281       </ul>
  282 </div>
  283 
  284 <div class="slide" id="s6">
  285   <div class="nav">
  286     <a href="#s5">&lt;</a>
  287     <a href="#s7">&gt;</a>
  288   </div>
  289   <h1>Review of Reflow</h1>
  290  <ul>
  291  <li>The reflowee sets various sizes in the reflow metrics after (possibly) reflowing some or all of its children 
  292     which reflows it children, etc.</li>
  293  <li>The reflowee returns a reflow status which indicates
  294      <ul class=nested>
  295       <li>if it is complete, and thus not have to continue (split)</li>
  296       <li>breaking status (in the case of some inline frames)</li> 
  297       <li>if there is truncation (it can't fit in the space and can't split). This is just a convience mechanism.</li>
  298      </ul>
  299     </li>
  300 
  301 </div>
  302 
  303 <div class="slide" id="s7">
  304   <div class="nav">
  305     <a href="#s6">&lt;</a>
  306     <a href="#s8">&gt;</a>
  307   </div>
  308 
  309   <h1>Kinds of reflows</h1>
  310   <ul>
  311     <li>Initial - reflowee's first reflow must be of this type (reflower's responsibility).</li> 
  312     <li>Resize - reflowee gets a change in available space only. Similar to initial, except it can reoccur.</li> 
  313     <li>Incremental - has a reflow path (tree) where each node has a command with a target frame, <br>reflow command types are:</li> 
  314      <ul class=nested>
  315       <li>dirty - something changed inside a target (e.g. it gains, loses children)</li>
  316       <li>style changed - a target changed stylisticly (recall, size is a style property)</li> 
  317       <li>content changed - a target's content changed (e.g. a text run)</li> 
  318       <li>user defined - currently only used for fixed positioned frames </li> 
  319      </ul>
  320     </li>
  321   </ul>
  322 </div>
  323 
  324 <div class="slide" id="s8">
  325   <div class="nav">
  326     <a href="#s7">&lt;</a>
  327     <a href="#s9">&gt;</a>
  328   </div>
  329   <h1>Kinds of reflows</h1>
  330   <ul>
  331     <li>Incremental reflow (continued)
  332      <ul class=nested>
  333       <li>reflower not allowed to change available size of reflowee</li>
  334       <li>reflow commands get coalesced to streamline processing</li> 
  335      </ul>
  336     </li>
  337     <li>Style change 
  338      <ul class=nested>
  339       <li>a target changed stylistic if there is a target, otherwise every frame may need to respond</li>
  340       <li>parent of target usually turns it into an incremental reflow with a style changed command type</li> 
  341      </ul>
  342     </li>
  343   </ul>
  344 </div>
  345 
  346 <div class="slide" id="s9">
  347   <div class="nav">
  348     <a href="#s8">&lt;</a>
  349     <a href="#s10">&gt;</a>
  350   </div>
  351   <h1>Table Frames</h1>
  352   <BR>
  353   <table class="tree" width=90%>
  354   <tr><td class=frame><td class=space style="width:2%"><td class=frame><td class=space style="width:2%">
  355       <td class=frame><td class=space><td class=frame></tr>
  356   <tr><td><td><td class=frame><td>
  357       <td>nsTableOuter Frame<td><td></tr>
  358   <tr class="arrows"><td><td><td><td class=left-arrow>&#x2199;<td><td class=right-arrow>&#x2198;</tr>
  359   <tr><td><td><td>nsTable<BR>Frame<td><td><td><td>nsTableCaption<BR>Frame</tr>
  360   <tr class="arrows"><td><td class=left-arrow>&#x2199;<td><td class=right-arrow>&#x2198;<td><td><td class=center-arrow>&darr;</tr>
  361   <tr><td>nsTableCol<BR>GroupFrame<td><td><TD><td>nsTableRow<BR>GroupFrame<td><td>nsBlockFrame</tr>
  362   <tr class="arrows"><td class=center-arrow>&darr;<td><td><td><td class=center-arrow>&darr;</tr>
  363   <tr><td>nsTableCol<BR>Frame<td><TD><TD><td>nsTableRow<BR>Frame</tr>
  364   <tr class="arrows"><td><td><td><td><td class=center-arrow>&darr;</tr>
  365   <tr><td><td><td><TD><td>nsTableCell<BR>Frame</tr>
  366   <tr class="arrows"><td><td><td><td><td class=center-arrow>&darr;</tr>
  367   <tr><td><td><td><TD><td>nsBlock<BR>Frame</tr>
  368   </table>
  369 </div>
  370 
  371 <div class="slide" id="s10">
  372   <div class="nav">
  373     <a href="#s9">&lt;</a>
  374     <a href="#s11">&gt;</a>
  375   </div>
  376   <h1>Table Reflow</h1>
  377   <ul>
  378     <li>table wrapper reflows table and caption (if present)</li>
  379     <li>Table reflows row groups in multiple passes</li> 
  380      <ul class=nested>
  381       <li>Pass 1 - unconstrained width, height and requests max elem width.</li>
  382       <li>The table figures out the column widths (balances) given the style width constraints
  383       on the table, col groups, cols, cells the preferred and max element sizes of the cells 
  384       (from the pass 1 reflow), and considers colspans</li> 
  385       <li>Pass 2 - cell widths are constrained by the column widths (heights are only 
  386       constrained in paginated mode).</li> 
  387      </ul>
  388     </li>
  389   </ul>
  390 </div>
  391 
  392 <div class="slide" id="s11">
  393   <div class="nav">
  394     <a href="#s10">&lt;</a>
  395     <a href="#s12">&gt;</a>
  396   </div>
  397   <h1>Table Reflow</h1>
  398   <ul>
  399     <li>Table reflows row groups (continued)</li> 
  400      <ul class=nested>
  401       <li>The row group figures out the row heights given the its style height constraints
  402       its rows and cells and the actual heights of its rows and cells from the pass 2 reflow</li> 
  403       <li>If the table has a style height, it allocates extra height to its row groups, rows and cells.</li> 
  404      </ul>
  405     </li>
  406     <li>In each pass, row groups reflow rows which reflow cells which reflow cell blocks</li>
  407   </ul>
  408 </div>
  409 
  410 <div class="slide" id="s12">
  411   <div class="nav">
  412     <a href="#s11">&lt;</a>
  413     <a href="#s13">&gt;</a>
  414   </div>
  415   <h1>Table Reflow Example</h1>
  416   <table width=100%>
  417    <tr>
  418     <td width=100%>
  419      <pre style="font-size:.6em;">
  420 tblW 030176CC r=0 a=8940,UC c=0,0 cnt=429
  421   tbl 030178C4 r=0 a=8940,UC c=4470,UC cnt=430
  422    rowG 03017A7C r=0 a=UC,UC c=UC,UC cnt=431 
  423     row 03017C08 r=0 a=UC,UC c=UC,UC cnt=432
  424      cell 03017DA8 r=0 a=UC,UC c=UC,UC cnt=433
  425       block 03017E08 r=0 a=UC,UC c=UC,UC cnt=434
  426       block 03017E08 d=870,300 me=480
  427      cell 03017DA8 d=930,360 me=540
  428      cell 0301A8CC r=0 a=UC,UC c=UC,UC cnt=436
  429       block 0301A92C r=0 a=UC,UC c=UC,UC cnt=437
  430       block 0301A92C d=1335,300 me=465
  431      cell 0301A8CC d=1395,360 me=525
  432     row 03017C08 d=UC,360
  433    rowG 03017A7C d=UC,360
  434    rowG 03017A7C r=2 a=4470,UC c=4470,UC cnt=442
  435     row 03017C08 r=2 a=4470,UC c=4470,UC cnt=443
  436      cell 03017DA8 r=2 a=1755,UC c=1695,UC cnt=444
  437       block 03017E08 r=2 a=1695,UC c=1695,UC cnt=445
  438       block 03017E08 d=1695,300
  439      cell 03017DA8 d=1755,360
  440      cell 0301A8CC r=2 a=2625,UC c=2565,UC cnt=446
  441       block 0301A92C r=2 a=2565,UC c=2565,UC cnt=447
  442       block 0301A92C d=2565,300
  443      cell 0301A8CC d=2625,360
  444     row 03017C08 d=4470,360
  445    rowG 03017A7C d=4470,360
  446   tbl 030178C4 d=4500,450
  447  tblW 030176CC d=4500,450
  448 
  449  <a href="frame_reflow_debug.html">frame reflow debugging</a> gives instructions 
  450  for turning this on.
  451  </pre>
  452    </td>
  453    <td>
  454      <pre style="font-size:.7em;">
  455 &lt;<span class=html>table</span> width=300&gt;
  456   &lt;<span class=html>tr</span>&gt;
  457     &lt;<span class=html>td</span>&gt;foo&lt;<span class=html>/td</span>&gt;
  458     &lt;<span class=html>td</span>&gt;bar zap&lt;<span class=html>/td</span>&gt;
  459   &lt;<span class=html>/tr</span>&gt;
  460 &lt;<span class=html>/table</span>&gt;
  461      </pre>
  462      <BR>
  463      <BR>
  464      <pre style="font-size:.7em;">
  465 Key:
  466 
  467   r  = reflow reason, 
  468        0 (initial),
  469        2 (resize) 
  470   a  = avail w, h
  471   c  = computed w, h
  472   d  = desired w, h
  473   me = max elem w
  474      <pre>
  475     </td>
  476   </tr>
  477  </table>
  478 </div>
  479 
  480 <div class="slide" id="s13">
  481   <div class="nav">
  482     <a href="#s12">&lt;</a>
  483     <a href="#s14">&gt;</a>
  484   </div>
  485   <h1>Table reflow optimizations</h1>
  486   <ul>
  487     <li>If the table is already balanced, pass 1 constrains the width (like a normal pass 2) based on the current
  488     column widths. The pass 2 will get skipped if the table doesn't need to rebalance. <!--<span class="comment">please clarify when can this happen</span>--></li> 
  489     <li>Nested table reflowed with an unconstrained width (i.e. an ancestor is doing a pass 1 reflow)
  490     will only do a pass 1 reflow on its children</li>
  491     <li>table wrapper caches last avail width and avoids reflowing children if resize reflow is the same as previous</li>
  492     <li>Table caches max element, preferred widths in case they are requested and it isn't rebalanced</li>
  493     <li>Cell caches prior avail width. if this doesn't change, the row may not have to reflow the cell</li>
  494   </ul>
  495 
  496 </div>
  497 
  498 <div class="slide" id="s14">
  499   <div class="nav">
  500     <a href="#s13">&lt;</a>
  501     <a href="#s15">&gt;</a>
  502   </div>
  503   <h1>Table incremental reflow</h1>
  504   <ul>
  505     <li>table wrapper is a target when a caption is added or removed (dirty) or the table or caption margin 
  506   changes (style changed).</li> 
  507     <li>Caption is a target when it changes stylistically (style changed).</li>
  508     <li>Table, row group, row, col group, col is a target when a child is added or removed (dirty) or it changes
  509   stylistically (style changed). <!--<span class="comment">please show how the column style change is propagated 
  510                into the cell reflows as the cells are reflowed by their parent rows and not cols</span>--></li>
  511     <li>In the dirty cases, a target posted the reflow command in AppendFrames, InsertFrames, or DeleteFrame.</li>
  512   </ul>
  513 </div>
  514 
  515 <div class="slide" id="s15">
  516   <div class="nav">
  517     <a href="#s14">&lt;</a>
  518     <a href="#s16">&gt;</a>
  519   </div>
  520   <h1>Table incremental reflow</h1>
  521   <ul>
  522     <li>In the style change cases where a target is between the table and the cell, the table is told to rebalance.</li>
  523     <li>When a target is the cell or below and the cell changes size, the row tells the table so it can decide if 
  524   it needs to rebalance</li>
  525     <li>When a target is inside the cell's block, the cell
  526   requests max element, preferred sizes of its block in case they change</li>
  527     <li>After the table reflows the row group(s) containing the targets, if it rebalances, it then does a pass 2 reflow.</li>
  528   </ul>
  529 </div>
  530 
  531 <div class="slide" id="s16">
  532   <div class="nav">
  533     <a href="#s15">&lt;</a>
  534     <a href="#s17">&gt;</a>
  535   </div>
  536   <h1>Special height reflow</h1>
  537   <ul>
  538     <li>When there is a % height frame inside a cell without a computed height</li>
  539       <ul class=nested>
  540         <li>the frame will never get a chance to size based on the final cell height</li>
  541         <li>in paginated mode when there is a height on the table, the table doesn't allocate
  542         extra height to rows until after it does a pass 2 reflow and then it is too late</li>
  543       </ul>
  544     </li>
  545     <li>This can be fixed by doing a special 3rd pass reflow</li>
  546   </ul>
  547   </div>
  548 </div>
  549 
  550 <div class="slide" id="s17">
  551   <div class="nav">
  552     <a href="#s16">&lt;</a>
  553     <a href="#s18">&gt;</a>
  554   </div>
  555   <h1>Special Reflow Example</h1>
  556   <table width=100% style="text-align:left;">
  557    <tr>
  558    <td>
  559      <pre style="font-size:.7em; text-align:left;">
  560 &lt;<span class=html>table</span> border=2 width=300&gt;
  561   &lt;<span class=html>tr</span>&gt;
  562     &lt;<span class=html>td</span>&gt;
  563       This cell's width is 
  564       constrained by the 
  565       table and image widths. 
  566       Its exact height is 
  567       hard to determine.
  568     &lt;<span class=html>/td</span>&gt;
  569     &lt;<span class=html>td</span>&gt;
  570       &lt;<span class=html>img</span> src=raptor.jpg
  571        width=200 height=100%>
  572     &lt;<span class=html>/td</span>&gt;
  573   &lt;<span class=html>/tr</span>&gt;
  574 &lt;<span class=html>/table</span>&gt;
  575      </pre>
  576    </td>
  577     <td>
  578      <table border=2 width=300>
  579       <tr>
  580        <td style="font-size:.7em;">This cell's width is constrained 
  581         by the table and image widths. <BR><BR>Its height
  582         is hard to determine.<BR><BR> The image needs to be as high as the cell.
  583        <td>
  584        <!-- need ?raw=1 for lxr to cough up the image data, not a pretty page -->
  585        <img src="raptor.jpg?raw=1" 
  586       width=200 height=100%>
  587     </td>
  588    </tr>
  589   </table>
  590 
  591   </tr>
  592  </table>
  593 </div>
  594 
  595 
  596 <div class="slide" id="s18">
  597   <div class="nav">
  598     <a href="#s17">&lt;</a>
  599     <a href="#s19">&gt;</a>
  600   </div>
  601   <h1>Special height reflow</h1>
  602   <ul>
  603     <li>The reflow state holds an observer and initiator</li>
  604     <li>Observer</li>
  605       <ul class=nested>
  606         <li>is the table cell used as the height basis</li>
  607         <li>set by frame without computed height in DidReflow</li>
  608         <li>gives its block a computed height during 3rd pass</li>
  609         <li>doesn't change height during 3rd pass</li>
  610       </ul>
  611     </li>
  612     <li>Initiator</li>
  613       <ul class=nested>
  614         <li>is the table containing the observer</li>
  615         <li>starts the 3rd pass reflow and sets a bit in the reflow state</li>
  616         <li>gives its block a computed height during 3rd pass</li>
  617         <li>could also be inside a cell which is an observer</li>
  618       </ul>
  619     </li>
  620 </div>
  621 
  622 <div class="slide" id="s19">
  623   <div class="nav">
  624     <a href="#s18">&lt;</a>
  625     <a href="#s20">&gt;</a>
  626   </div>
  627   <h1>Special height reflow</h1>
  628   <ul>
  629     <li>Optimizations</li>
  630       <ul class=nested>
  631         <li>only frames needing 3rd pass actually get it</li>
  632         <li>frames gettting a 3rd pass only get it once</li>
  633       </ul>
  634     </li>
  635 </div>
  636 
  637 <div class="slide" id="s20">
  638   <div class="nav">
  639     <a href="#s19">&lt;</a>
  640     <a href="#s21">&gt;</a>
  641   </div>
  642   <h1>Intro to paginated reflow</h1>
  643   <ul>
  644     <li>When a reflowee's available height is constrained, it may not fit and need to either 
  645     split/continue on the next page, or start on the next page.</li>
  646       <ul class=nested>
  647         <li>If it can continue, it returns an incomplete status.</li>
  648         <li>If it can't continue it returns a complete status.</li>
  649       </ul>
  650     </li>
  651     <li>A continuation may also need to be continued</li>
  652     <li>Continuations are linked together by prevInFlow and nextInFlow pointers </li>
  653   </ul>
  654 </div>
  655 
  656 <div class="slide" id="s21">
  657   <div class="nav">
  658     <a href="#s20">&lt;</a>
  659     <a href="#s22">&gt;</a>
  660   </div>
  661   <h1>Pagination Illustration</h1>
  662   <table class=box style="height:500px">
  663    <tr><td class="title">nsSimplePageSequence</td></tr>
  664    <tr>
  665     <td class=box>
  666      <table class=box style="height:40%;">
  667       <tr><td class=title>nsPageFrame</td></tr>
  668       <tr>
  669        <td class=box>
  670         <table class=box style="height:100%;">
  671          <tr><td class=title>nsPageContentFrame</td></tr>
  672          <tr>
  673           <td class=box style="border-bottom: hidden">
  674            <table class=box style="height:100%; border-bottom:hidden">
  675             <tr><td class=title>areaFrame (html)</td></tr>
  676             <tr>
  677              <td class=box>
  678               <table class=box style="height:100%; border-bottom:hidden">
  679                <tr><td class=title>blockFrame (body)</td></tr>
  680                <tr>
  681                 <td class=box>
  682                  <table class=box style="height:100%; border-bottom:hidden">
  683                   <tr><td class=title>nsTableWrapperFrame</td></tr>
  684                   <tr>
  685                    <td class=box></td>
  686                   </tr>
  687                  </table>
  688                 </td>
  689                </tr>
  690               </table>
  691              </td>
  692             </tr>
  693            </table>
  694          </tr>
  695         </table>
  696        </td>
  697       </tr>
  698      </table>
  699      <BR>
  700      <table class=box style="height:40%;">
  701       <tr>
  702        <td class=box>
  703         <table class=box style="height:100%;">
  704          <tr>
  705           <td class=box style="border-top: hidden">
  706            <table class=box style="height:100%; border-top:hidden">
  707             <tr>
  708              <td class=box>
  709               <table class=box style="height:100%; border-top:hidden">
  710                <tr>
  711                 <td class=box>
  712                  <table class=box style="height:100%; border-top:hidden">
  713                   <tr>
  714                    <td class=box></td>
  715                   </tr>
  716                   <tr><td class=title2>nsTableWrapperFrame</td></tr>
  717                  </table>
  718                 </td>
  719                </tr>
  720                <tr><td class=title2>blockFrame (body)</td></tr>
  721               </table>
  722              </td>
  723             </tr>
  724             <tr><td class=title2>areaFrame (html)</td></tr>
  725            </table>
  726          </tr>
  727          <tr><td class=title2>nsPageContentFrame continued</td></tr>
  728         </table>
  729        </td>
  730       </tr>
  731       <tr><td class=title2>nsPageFrame continued</td></tr>
  732      </table>
  733     </td>
  734    </tr>
  735   </table>
  736 </div>
  737 
  738 <div class="slide" id="s22">
  739   <div class="nav">
  740     <a href="#s21">&lt;</a>
  741     <a href="#s23">&gt;</a>
  742   </div>
  743   <h1>Intro to paginated reflow</h1>
  744   <ul>
  745     <li>The page sequence starts with one page and reflows it. If the page is incomplete then the page sequence
  746         creates a continuation for the page and sets it as the page's next sibling (it is also the page's 
  747         nextInFlow).</li>
  748     <li>The page was incomplete because the page content was incomplete because the doc root was incomplete</li>
  749     <li>The doc root was incomplete because it contained lines that didn't fit (or if it was mapped to a table, 
  750         because the table didn't fit) becacause a line contained something that didn't fit, etc.</li>
  751   </ul>
  752 </div>
  753 
  754 <div class="slide" id="s23">
  755   <div class="nav">
  756     <a href="#s22">&lt;</a>
  757     <a href="#s24">&gt;</a>
  758   </div>
  759   <h1>Intro to paginated reflow</h1>
  760   <ul>
  761     <li>If the reflowee is incomplete, the reflower has the responsiblity to:
  762       <ul>
  763         <li>Create a continuation for the reflowee</li>
  764         <li>Ensure that the continuation gets put in the frame hierarchy at the right place
  765         and gets reflowed at the right time.</li>
  766         <li>Typically, a reflower accomplishes this by putting the continuation (c) on an overflow 
  767         list which the reflower owns. When the reflower's continuation gets reflowed, it takes c 
  768         and its siblings as children and reflows them.</li>
  769       </ul>
  770     </li>
  771     <li>If the reflowee is complete, truncated (it didn't fit), not at the top of page, 
  772     the reflower should put the reflowee on its overflow list and return an incomplete status.</li>
  773   </ul>
  774 </div>
  775 
  776 <div class="slide" id="s24">
  777   <div class="nav">
  778     <a href="#s23">&lt;</a>
  779     <a href="#s25">&gt;</a>
  780   </div>
  781   <h1>Intro to paginated reflow</h1>
  782   <ul>
  783     <li>Special assumptions
  784       <ul>
  785         <li>There are only initial and (possibly) resize reflows. Incremental 
  786         and style change reflows are not allowed.</li>
  787         <li>Multiple resize reflows may be necessary (e.g. a child is truncated and gets reflowed on a 
  788         subsequent page) but they should not change the available width from the last time.</li>
  789         <li>Multiple resize reflows may require special handling if a frame split previously. It may need
  790         to "pull up" children from a continuation.</li>
  791       </ul>
  792     </li>
  793   </ul>
  794 </div>
  795 
  796 <div class="slide" id="s25">
  797   <div class="nav">
  798     <a href="#s24">&lt;</a>
  799     <a href="#s26">&gt;</a>
  800   </div>
  801   <h1>Table paginated reflow</h1>
  802   <ul>
  803     <li>The block containing the table wrapper reflows it. If it is incomplete, the block will
  804       <ul>
  805         <li>create a continuation for the table wrapper (which also creates a continuation for the table).</li>
  806         <li>put the continuation on a new line and place that line on its overflow lines property.</li>
  807       </ul>
  808     </li>
  809     <li>The table wrapper reflows the table and just returns the status of the table.</li>
  810     <li>The table does a pass 1 reflow and balances. If it is incomplete,</li>
  811       <ul>
  812         <li>it will become the first-in-flow</li>
  813         <li>it will be the only frame among its continuations to ever balance or calc the cell map, and it only
  814         does this once</li>
  815       </ul>
  816     </li>
  817   </ul>
  818 </div>
  819 
  820 <div class="slide" id="s26">
  821   <div class="nav">
  822     <a href="#s25">&lt;</a>
  823     <a href="#s27">&gt;</a>
  824   </div>
  825   <h1>Table paginated reflow</h1>
  826   <ul>
  827     <li>The table does a pass 2 reflow constraining both avail heights and widths. If a row group is incomplete, the table
  828       <ul>
  829         <li>creates a continuation for the row group</li>
  830         <li>puts the continuation in its overflow frames property</li>
  831       </ul>
  832     </li>
  833     <li>What follows only applies during the pass 2 reflow.</li>
  834     <li>The row group</li>
  835       <ul>
  836         <li>reflows all of its rows with unconstrained heights and calculates the row heights,</li>
  837         <li>figures out which row falls on a page boundary and reflows it with a constrained height. If there
  838         will be a pass 3 reflow then this should (bug) happen at that time instead.</li>
  839       </ul>
  840     </li>
  841   </ul>
  842 </div>
  843 
  844 <div class="slide" id="s27">
  845   <div class="nav">
  846     <a href="#s26">&lt;</a>
  847     <a href="#s28">&gt;</a>
  848   </div>
  849   <h1>Table paginated reflow</h1>
  850   <ul>
  851     <li>The row group (continued)</li>
  852       <ul>
  853         <li>creates a continuation for the incomplete row (which also creates continuations for all of its cells
  854         and all of the cell blocks)</li>
  855         <li>puts the continuation in its overflow frames property. If the row was truncated and not top of page,
  856         the row is put in the overflow frames property.
  857       </ul>
  858     </li>
  859   </ul>
  860 </div>
  861 
  862 <div class="slide" id="s28">
  863   <div class="nav">
  864     <a href="#s27">&lt;</a>
  865     <a href="#s0">&gt;</a>
  866   </div>
  867   <h1>Table paginated reflow</h1>
  868   <ul>
  869     <li>The row and cells (getting the constrained height reflow) just reflow their children with a constrained height.  
  870     They don't need an overflow list for continued children because the continuations were created when the
  871     row group created the row's continutation.</li>
  872     <li>A cell is incomplete because its block is incomplete. The block uses the overflow lines mechanism 
  873     (mentioned above) for its continued children</li>
  874     </li>
  875     <li>There are two splitting scenarios for a table
  876       <ul>
  877         <li>An incomplete cells block causes the cell, row, row group, table, table wrapper to
  878         be incomplete</li>
  879         <li>A truncated row or a row that started too far down the page causes the row group, 
  880         table, table wrapper to be incomplete.</li>
  881       </ul>
  882     </li>
  883   </ul>
  884 </div>
  885 
  886 
  887 </body>
  888 </html>