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1 <!-- vim:sw=2:et:ts=2:tw=72:
2 -->
6 <head>
13 }
15 body {
21 }
25 }
27 h1 {
30 /* text-align: center; */
34 }
36 h2 {
41 }
43 ul {
46 }
56 }
59 /*
60 position: absolute;
61 top: 4px;
62 right: 4px;
63 */
66 }
74 }
78 }
80 table {
82 }
90 }
92 row {
94 }
97 }
99 table td {
100 /*text-align: center;*/
102 }
107 }
114 }
121 }
128 }
132 }
136 }
140 }
144 }
148 }
152 }
156 }
158 </style>
159 </head>
160 <body>
166 </div>
168 <center>
172 </center>
173 </td></tr></table>
175 </div>
181 </div>
183 <ul>
189 </ul>
190 </div>
196 </div>
198 <ul>
199 <li>Reflow process starts when
200 <ul>
201 <li>An html document starts loading (the frame tree contains only viewport, scroll(s), canvas, html, body).</li>
203 <li>The initial chunk of an html doc (or a subsequent chunk of an xml doc) is loaded. The container posts a
204 dirty reflow command with itself as the target. </li>
205 <li>Content is inserted, appended, or deleted through the DOM. The container posts a dirty reflow command
206 with itself as the target.</li>
207 <li>Style changes through the DOM - javascript, browser change font (CTRL+/-), a preference changes, etc.</li>
208 </ul>
209 </li>
210 </ul>
211 </div>
217 </div>
219 <ul>
220 <li>Reflow starts with pres shell
221 <ul>
224 </ul>
225 </li>
227 <li>The reflower
228 <ul>
229 <li>Positions reflowee (if it can) before actually reflowing in case views are involved
230 (e.g. absolutely positioned elements) </li>
232 </ul>
233 </li>
234 </ul>
235 </div>
241 </div>
243 <ul>
244 <li>The reflow state:
245 <ul>
247 <li>contains:
248 <ul>
254 </ul>
255 </li>
256 </ul>
257 </li>
258 </ul>
259 </div>
265 </div>
267 <ul>
268 </li>
269 <li>the reflow metrics contains:
272 <li>preferred size (if requested) - the size it would like to be given no size constraints.</li>
273 <li>desired size - the size it would like to be given the avail size. This
274 is equivalent to preferred size if the avail size is not constrained.</li>
275 </ul>
276 </li>
277 </ul>
278 </div>
284 </div>
286 <ul>
287 <li>The reflowee sets various sizes in the reflow metrics after (possibly) reflowing some or all of its children
288 which reflows it children, etc.</li>
289 <li>The reflowee returns a reflow status which indicates
293 <li>if there is truncation (it can't fit in the space and can't split). This is just a convience mechanism.</li>
294 </ul>
295 </li>
297 </div>
303 </div>
306 <ul>
308 <li>Resize - reflowee gets a change in available space only. Similar to initial, except it can reoccur.</li>
309 <li>Incremental - has a reflow path (tree) where each node has a command with a target frame, <br>reflow command types are:</li>
315 </ul>
316 </li>
317 </ul>
318 </div>
324 </div>
326 <ul>
327 <li>Incremental reflow (continued)
331 </ul>
332 </li>
333 <li>Style change
335 <li>a target changed stylistic if there is a target, otherwise every frame may need to respond</li>
336 <li>parent of target usually turns it into an incremental reflow with a style changed command type</li>
337 </ul>
338 </li>
339 </ul>
340 </div>
346 </div>
348 <BR>
350 <tr><td class=frame><td class=space style="width:2%"><td class=frame><td class=space style="width:2%">
354 <tr class="arrows"><td><td><td><td class=left-arrow>↙<td><td class=right-arrow>↘</tr>
356 <tr class="arrows"><td><td class=left-arrow>↙<td><td class=right-arrow>↘<td><td><td class=center-arrow>↓</tr>
357 <tr><td>nsTableCol<BR>GroupFrame<td><td><TD><td>nsTableRow<BR>GroupFrame<td><td>nsBlockFrame</tr>
364 </table>
365 </div>
371 </div>
373 <ul>
378 <li>The table figures out the column widths (balances) given the style width constraints
379 on the table, col groups, cols, cells the preferred and max element sizes of the cells
382 constrained in paginated mode).</li>
383 </ul>
384 </li>
385 </ul>
386 </div>
392 </div>
394 <ul>
397 <li>The row group figures out the row heights given the its style height constraints
399 <li>If the table has a style height, it allocates extra height to its row groups, rows and cells.</li>
400 </ul>
401 </li>
403 </ul>
404 </div>
410 </div>
413 <tr>
446 for turning this on.
447 </pre>
448 </td>
449 <td>
457 </pre>
458 <BR>
459 <BR>
461 Key:
463 r = reflow reason,
464 0 (initial),
465 2 (resize)
466 a = avail w, h
467 c = computed w, h
468 d = desired w, h
469 me = max elem w
470 <pre>
471 </td>
472 </tr>
473 </table>
474 </div>
480 </div>
482 <ul>
483 <li>If the table is already balanced, pass 1 constrains the width (like a normal pass 2) based on the current
484 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>
485 <li>Nested table reflowed with an unconstrained width (i.e. an ancestor is doing a pass 1 reflow)
487 <li>Outer table caches last avail width and avoids reflowing children if resize reflow is the same as previous</li>
488 <li>Table caches max element, preferred widths in case they are requested and it isn't rebalanced</li>
489 <li>Cell caches prior avail width. if this doesn't change, the row may not have to reflow the cell</li>
490 </ul>
492 </div>
498 </div>
500 <ul>
501 <li>Outer table is a target when a caption is added or removed (dirty) or the table or caption margin
502 changes (style changed).</li>
504 <li>Table, row group, row, col group, col is a target when a child is added or removed (dirty) or it changes
505 stylistically (style changed). <!--<span class="comment">please show how the column style change is propagated
506 into the cell reflows as the cells are reflowed by their parent rows and not cols</span>--></li>
507 <li>In the dirty cases, a target posted the reflow command in AppendFrames, InsertFrames, or DeleteFrame.</li>
508 </ul>
509 </div>
515 </div>
517 <ul>
518 <li>In the style change cases where a target is between the table and the cell, the table is told to rebalance.</li>
519 <li>When a target is the cell or below and the cell changes size, the row tells the table so it can decide if
520 it needs to rebalance</li>
521 <li>When a target is inside the cell's block, the cell
522 requests max element, preferred sizes of its block in case they change</li>
523 <li>After the table reflows the row group(s) containing the targets, if it rebalances, it then does a pass 2 reflow.</li>
524 </ul>
525 </div>
531 </div>
533 <ul>
537 <li>in paginated mode when there is a height on the table, the table doesn't allocate
539 </ul>
540 </li>
542 </ul>
543 </div>
544 </div>
550 </div>
553 <tr>
554 <td>
559 This cell's width is
560 constrained by the
561 table and image widths.
562 Its exact height is
563 hard to determine.
571 </pre>
572 </td>
573 <td>
575 <tr>
577 by the table and image widths. <BR><BR>Its height
578 is hard to determine.<BR><BR> The image needs to be as high as the cell.
579 <td>
580 <!-- need ?raw=1 for lxr to cough up the image data, not a pretty page -->
583 </td>
584 </tr>
585 </table>
587 </tr>
588 </table>
589 </div>
596 </div>
598 <ul>
606 </ul>
607 </li>
614 </ul>
615 </li>
616 </div>
622 </div>
624 <ul>
629 </ul>
630 </li>
631 </div>
637 </div>
639 <ul>
640 <li>When a reflowee's available height is constrained, it may not fit and need to either
641 split/continue on the next page, or start on the next page.</li>
645 </ul>
646 </li>
649 </ul>
650 </div>
656 </div>
660 <tr>
664 <tr>
668 <tr>
672 <tr>
676 <tr>
680 <tr>
682 </tr>
683 </table>
684 </td>
685 </tr>
686 </table>
687 </td>
688 </tr>
689 </table>
690 </tr>
691 </table>
692 </td>
693 </tr>
694 </table>
695 <BR>
697 <tr>
700 <tr>
703 <tr>
706 <tr>
709 <tr>
711 </tr>
713 </table>
714 </td>
715 </tr>
717 </table>
718 </td>
719 </tr>
721 </table>
722 </tr>
724 </table>
725 </td>
726 </tr>
728 </table>
729 </td>
730 </tr>
731 </table>
732 </div>
738 </div>
740 <ul>
741 <li>The page sequence starts with one page and reflows it. If the page is incomplete then the page sequence
742 creates a continuation for the page and sets it as the page's next sibling (it is also the page's
743 nextInFlow).</li>
744 <li>The page was incomplete because the page content was incomplete because the doc root was incomplete</li>
745 <li>The doc root was incomplete because it contained lines that didn't fit (or if it was mapped to a table,
746 because the table didn't fit) becacause a line contained something that didn't fit, etc.</li>
747 </ul>
748 </div>
754 </div>
756 <ul>
757 <li>If the reflowee is incomplete, the reflower has the responsiblity to:
758 <ul>
760 <li>Ensure that the continuation gets put in the frame hierarchy at the right place
761 and gets reflowed at the right time.</li>
762 <li>Typically, a reflower accomplishes this by putting the continuation (c) on an overflow
763 list which the reflower owns. When the reflower's continuation gets reflowed, it takes c
764 and its siblings as children and reflows them.</li>
765 </ul>
766 </li>
767 <li>If the reflowee is complete, truncated (it didn't fit), not at the top of page,
768 the reflower should put the reflowee on its overflow list and return an incomplete status.</li>
769 </ul>
770 </div>
776 </div>
778 <ul>
779 <li>Special assumptions
780 <ul>
781 <li>There are only initial and (possibly) resize reflows. Incremental
782 and style change reflows are not allowed.</li>
783 <li>Multiple resize reflows may be necessary (e.g. a child is truncated and gets reflowed on a
784 subsequent page) but they should not change the available width from the last time.</li>
785 <li>Multiple resize reflows may require special handling if a frame split previously. It may need
787 </ul>
788 </li>
789 </ul>
790 </div>
796 </div>
798 <ul>
799 <li>The block containing the outer table reflows it. If it is incomplete, the block will
800 <ul>
801 <li>create a continuation for the outer table (which also creates a continuation for the table).</li>
803 </ul>
804 </li>
807 <ul>
809 <li>it will be the only frame among its continuations to ever balance or calc the cell map, and it only
810 does this once</li>
811 </ul>
812 </li>
813 </ul>
814 </div>
820 </div>
822 <ul>
823 <li>The table does a pass 2 reflow constraining both avail heights and widths. If a row group is incomplete, the table
824 <ul>
827 </ul>
828 </li>
831 <ul>
833 <li>figures out which row falls on a page boundary and reflows it with a constrained height. If there
835 </ul>
836 </li>
837 </ul>
838 </div>
844 </div>
846 <ul>
848 <ul>
849 <li>creates a continuation for the incomplete row (which also creates continuations for all of its cells
850 and all of the cell blocks)</li>
851 <li>puts the continuation in its overflow frames property. If the row was truncated and not top of page,
852 the row is put in the overflow frames property.
853 </ul>
854 </li>
855 </ul>
856 </div>
862 </div>
864 <ul>
865 <li>The row and cells (getting the constrained height reflow) just reflow their children with a constrained height.
866 They don't need an overflow list for continued children because the continuations were created when the
867 row group created the row's continutation.</li>
868 <li>A cell is incomplete because its block is incomplete. The block uses the overflow lines mechanism
869 (mentioned above) for its continued children</li>
870 </li>
871 <li>There are two splitting scenarios for a table
872 <ul>
873 <li>An incomplete cells block causes the cell, row, row group, table, outer table to
874 be incomplete</li>
875 <li>A truncated row or a row that started too far down the page causes the row group,
876 table, outer table to be incomplete.</li>
877 </ul>
878 </li>
879 </ul>
880 </div>
883 </body>
884 </html>