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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/. -->
5 <!-- vim:sw=2:et:ts=2:tw=72:
6 -->
10 <head>
17 }
19 body {
25 }
29 }
31 h1 {
34 /* text-align: center; */
38 }
40 h2 {
45 }
47 ul {
50 }
60 }
63 /*
64 position: absolute;
65 top: 4px;
66 right: 4px;
67 */
70 }
78 }
82 }
84 table {
86 }
94 }
96 row {
98 }
101 }
103 table td {
104 /*text-align: center;*/
106 }
111 }
118 }
125 }
132 }
136 }
140 }
144 }
148 }
152 }
156 }
160 }
162 </style>
163 </head>
164 <body>
170 </div>
172 <center>
176 </center>
177 </td></tr></table>
179 </div>
185 </div>
187 <ul>
193 </ul>
194 </div>
200 </div>
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>
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>
221 </div>
223 <ul>
224 <li>Reflow starts with pres shell
225 <ul>
228 </ul>
229 </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>
236 </ul>
237 </li>
238 </ul>
239 </div>
245 </div>
247 <ul>
248 <li>The reflow state:
249 <ul>
251 <li>contains:
252 <ul>
258 </ul>
259 </li>
260 </ul>
261 </li>
262 </ul>
263 </div>
269 </div>
271 <ul>
272 </li>
273 <li>the reflow metrics contains:
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>
288 </div>
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
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>
301 </div>
307 </div>
310 <ul>
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>
319 </ul>
320 </li>
321 </ul>
322 </div>
328 </div>
330 <ul>
331 <li>Incremental reflow (continued)
335 </ul>
336 </li>
337 <li>Style change
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>
350 </div>
352 <BR>
354 <tr><td class=frame><td class=space style="width:2%"><td class=frame><td class=space style="width:2%">
358 <tr class="arrows"><td><td><td><td class=left-arrow>↙<td><td class=right-arrow>↘</tr>
360 <tr class="arrows"><td><td class=left-arrow>↙<td><td class=right-arrow>↘<td><td><td class=center-arrow>↓</tr>
361 <tr><td>nsTableCol<BR>GroupFrame<td><td><TD><td>nsTableRow<BR>GroupFrame<td><td>nsBlockFrame</tr>
368 </table>
369 </div>
375 </div>
377 <ul>
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
386 constrained in paginated mode).</li>
387 </ul>
388 </li>
389 </ul>
390 </div>
396 </div>
398 <ul>
401 <li>The row group figures out the row heights given the its style height constraints
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>
407 </ul>
408 </div>
414 </div>
417 <tr>
450 for turning this on.
451 </pre>
452 </td>
453 <td>
461 </pre>
462 <BR>
463 <BR>
465 Key:
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>
484 </div>
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)
491 <li>Outer table 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>
496 </div>
502 </div>
504 <ul>
505 <li>Outer table is a target when a caption is added or removed (dirty) or the table or caption margin
506 changes (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>
519 </div>
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>
535 </div>
537 <ul>
541 <li>in paginated mode when there is a height on the table, the table doesn't allocate
543 </ul>
544 </li>
546 </ul>
547 </div>
548 </div>
554 </div>
557 <tr>
558 <td>
563 This cell's width is
564 constrained by the
565 table and image widths.
566 Its exact height is
567 hard to determine.
575 </pre>
576 </td>
577 <td>
579 <tr>
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 -->
587 </td>
588 </tr>
589 </table>
591 </tr>
592 </table>
593 </div>
600 </div>
602 <ul>
610 </ul>
611 </li>
618 </ul>
619 </li>
620 </div>
626 </div>
628 <ul>
633 </ul>
634 </li>
635 </div>
641 </div>
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>
649 </ul>
650 </li>
653 </ul>
654 </div>
660 </div>
664 <tr>
668 <tr>
672 <tr>
676 <tr>
680 <tr>
684 <tr>
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>
701 <tr>
704 <tr>
707 <tr>
710 <tr>
713 <tr>
715 </tr>
717 </table>
718 </td>
719 </tr>
721 </table>
722 </td>
723 </tr>
725 </table>
726 </tr>
728 </table>
729 </td>
730 </tr>
732 </table>
733 </td>
734 </tr>
735 </table>
736 </div>
742 </div>
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>
758 </div>
760 <ul>
761 <li>If the reflowee is incomplete, the reflower has the responsiblity to:
762 <ul>
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>
780 </div>
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
791 </ul>
792 </li>
793 </ul>
794 </div>
800 </div>
802 <ul>
803 <li>The block containing the outer table reflows it. If it is incomplete, the block will
804 <ul>
805 <li>create a continuation for the outer table (which also creates a continuation for the table).</li>
807 </ul>
808 </li>
811 <ul>
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>
824 </div>
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>
831 </ul>
832 </li>
835 <ul>
837 <li>figures out which row falls on a page boundary and reflows it with a constrained height. If there
839 </ul>
840 </li>
841 </ul>
842 </div>
848 </div>
850 <ul>
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>
866 </div>
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, outer table 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, outer table to be incomplete.</li>
881 </ul>
882 </li>
883 </ul>
884 </div>
887 </body>
888 </html>