Hopefully finish up the last part of the pagination algo.

Author: tabatkins

css3-flexbox/Overview.html

@@ -2419,11 +2419,12 @@ <h2 id=pagination><span class=secno>10. </span> Page breaks in flexbox</h2>
         and the flexbox is not at the top of the page already, move the
         flexbox to the next page and restart flexbox layout entirely.
 
-       <li> If there are any flexbox items not laid out by the previous step,
+       <li> If there are any flexbox items not laid out by the first step,
         rerun the flexbox sizing algorithm from <a href="#main-sizing">Main
         Sizing Determination</a> through <a href="#cross-sizing">Cross Sizing
-        Determination</a>, and return to the previous step, starting from the
-        first item not already laid out.
+        Determination</a> using only the items not laid out on a previous
+        line, and return to the previous step, starting from the first item
+        not already laid out.
       </ol>
 
      <li> If there are any flexbox items not laid out by the previous step,
@@ -2464,14 +2465,14 @@ <h2 id=pagination><span class=secno>10. </span> Page breaks in flexbox</h2>
      <li> For each item, lay out as much of its contents as will fit in the
       space left on the page, and fragment the remaining content onto the
       next page, rerunning the flexbox sizing algorithm from <a
-      href="#line-sizing">Line Sizing Determination</a> through <a
+      href="#line-sizing">Line Length Determination</a> through <a
       href="#main-alignment">Main-Axis Alignment</a> into the new page size
       using <em>all</em> the contents (including items completed on previous
       pages).
       <p class=note> Any flexbox items that fit entirely into previous
        fragments still take up space in the main axis in later fragments.
 
-     <li> For each fragment of the flexbox, continue the flexbox layout
+     <li> For each fragment of the flexbox, rerun the flexbox layout
       algorithm from <a href="#cross-alignment">Cross-Axis Alignment</a> to
       its finish. For all fragments besides the first, treat &lsquo;<a
       href="#flex-item-align"><code
@@ -2492,52 +2493,42 @@ <h2 id=pagination><span class=secno>10. </span> Page breaks in flexbox</h2>
 
    <dd>
     <ol>
-     <li>Collect items into lines and determine line heights:
-      <ol>
-       <li>
-        <p>If &lsquo;<a href="#flex-line-pack0"><code
-         class=property>flex-line-pack</code></a>&rsquo; is &lsquo;<code
-         class=property>stretch</code>&rsquo; and flexbox size in block
-         direction is definite, layout of the complete flexbox has to be done
-         first to determine line heights. Layout is done as usual for
-         non-paginated case, but accounting for forced breaks.
-
-        <p>If page size varies, this step may have to be redone, again with
-         complete content; special consideration should be to be given to
-         line breaks to ensure that item at the start of current page is also
-         at the start of a line in this hypothetical layout. This
-         specification currently doesn't define how exactly to achieve that.
-
-       <li>Otherwise, items are collected into lines and each line is laid
-        out as a single-line flexbox to determine block-direction size of
-        each line.
-      </ol>
-
-     <li>Lines are added one at a time, until out of available space or a
-      forced break is encountered
+     <li> Run the flexbox sizing algorithm (without regards to pagination),
+      through <a href="#cross-sizing">Cross Sizing Determination</a>.
 
-     <li>Breaks inside items (forced or unforced) are not allowed.
+     <li> Lay out as many flexbox lines as possible (but at least one),
+      starting from the first, until there is no more room on the page or a
+      forced break is encountered.
+      <p> If a line doesn't fit on the page, and the line is not at the top
+       of the page, move the line to the next page and restart the flexbox
+       layout algorithm entirely, using only the items in and following this
+       line.
+
+      <p> If a flexbox item itself causes a forced break, rerun the flexbox
+       layout algorithm from <a href="#main-sizing">Main Sizing
+       Determination</a> through <a href="#main-alignment">Main-Axis
+       Alignment</a>, using only the items on this and following lines, but
+       with the item causing the break automatically starting a new line in
+       the <a href="#algo-line-break"> step, then continue with this step.
+       Forced breaks <em>within</em> flexbox items are ignored. </a>
 
-     <li>If the first flexbox line on a page doesn't fit in cross-axis,
-      <ol>
-       <li>If the flexbox is not at the top of the page, it is moved to the
-        next page.
-
-       <li>If the flexbox is already at the top of the page, the item may
-        produce overflow. If &lsquo;<code
-        class=property>overflow</code>&rsquo; property of the flexbox is set
-        to &lsquo;<code class=property>visible</code>&rsquo;, it is paginated
-        using same rules as visible overflow of blocks in normal flow.
-      </ol>
-
-     <li>If size of flexbox in inline direction is not definite, multi-line
-      layout algorithm is run using the set of items that have fit on the
-      current page.
+     <li> If there are any flexbox items not laid out by the previous step,
+      rerun the flexbox sizing algorithm from <a href="#line-sizing">Line
+      Length Determination</a> through <a href="#main-alignment">Main-Axis
+      Alignment</a> with the next page's size and only the items not already
+      laid out. Return to the previous step, but starting from the first line
+      not already laid out.
 
-     <li>Line packing is done on each page, with content on the page
+     <li> For each fragment of the flexbox, continue the flexbox layout
+      algorithm from <a href="#cross-alignment">Cross Axis Alignment</a> to
+      its finish.
     </ol>
   </dl>
 
+  <p class=issue> I think we need to explicitly handle a definite size in the
+   fragmentation axis, and running out of space. (I think it just lays out as
+   continuous media within the overflow area.)
+
   <h2 id=cssom><span class=secno>11. </span>CSSOM</h2>
 
   <div class=issue>

css3-flexbox/Overview.src.html

@@ -1776,10 +1776,11 @@ <h2 id="pagination">
 							and restart flexbox layout entirely.
 
 						<li>
-							If there are any flexbox items not laid out by the previous step,
+							If there are any flexbox items not laid out by the first step,
 							rerun the flexbox sizing algorithm 
 							from <a href="#main-sizing">Main Sizing Determination</a>
-							through <a href="#cross-sizing">Cross Sizing Determination</a>,
+							through <a href="#cross-sizing">Cross Sizing Determination</a>
+							using only the items not laid out on a previous line,
 							and return to the previous step,
 							starting from the first item not already laid out.
 					</ol>
@@ -1831,7 +1832,7 @@ <h2 id="pagination">
 					lay out as much of its contents as will fit in the space left on the page,
 					and fragment the remaining content onto the next page,
 					rerunning the flexbox sizing algorithm
-					from <a href="#line-sizing">Line Sizing Determination</a>
+					from <a href="#line-sizing">Line Length Determination</a>
 					through <a href="#main-alignment">Main-Axis Alignment</a>
 					into the new page size
 					using <em>all</em> the contents (including items completed on previous pages).					
@@ -1842,7 +1843,7 @@ <h2 id="pagination">
 
 				<li>
 					For each fragment of the flexbox,
-					continue the flexbox layout algorithm
+					rerun the flexbox layout algorithm
 					from <a href="#cross-alignment">Cross-Axis Alignment</a>
 					to its finish.
 					For all fragments besides the first,
@@ -1855,42 +1856,63 @@ <h2 id="pagination">
 					would fit entirely within a single flexbox fragment,
 					it may be shifted into that fragment
 					and aligned appropriately.
-			</ol>		
+			</ol>
 
 		<dt>Multi-line row flexbox
 		<dd>
 			<ol>
-				<li>Collect items into lines and determine line heights:
-					
-					<ol>
-						<li>
-							<p>If 'flex-line-pack' is 'stretch' and flexbox size in block direction is definite, layout of the complete flexbox has to be done first to determine line heights. Layout is done as usual for non-paginated case, but accounting for forced breaks.
-			
-							<p>If page size varies, this step may have to be redone, again with complete content; special consideration should be to be given to line breaks to ensure that item at the start of current page is also at the start of a line in this hypothetical layout. This specification currently doesn't define how exactly to achieve that.
-						
-
-						<li>Otherwise, items are collected into lines and each line is laid out as a single-line flexbox to determine block-direction size of each line.
-					</ol>
-					
+				<li>
+					Run the flexbox sizing algorithm (without regards to pagination),
+					through <a href="#cross-sizing">Cross Sizing Determination</a>.
 
-				<li>Lines are added one at a time, until out of available space or a forced break is encountered
+				<li>
+					Lay out as many flexbox lines as possible
+					(but at least one),
+					starting from the first,
+					until there is no more room on the page
+					or a forced break is encountered.
 
-				<li>Breaks inside items (forced or unforced) are not allowed.
-				<li>If the first flexbox line on a page doesn't fit in 
-				cross-axis,
-				<ol>
-					<li>If the flexbox is not at the top of the page, it is moved to the next page.
-					<li>If the flexbox is already at the top of the page, the item may produce overflow. If 'overflow' property of the flexbox is set to 'visible', it is paginated using same rules as visible overflow of blocks in normal flow.
-				</ol>
-				
+					<p>
+						If a line doesn't fit on the page,
+						and the line is not at the top of the page,
+						move the line to the next page
+						and restart the flexbox layout algorithm entirely,
+						using only the items in and following this line.
+
+					<p>
+						If a flexbox item itself causes a forced break,
+						rerun the flexbox layout algorithm
+						from <a href="#main-sizing">Main Sizing Determination</a>
+						through <a href="#main-alignment">Main-Axis Alignment</a>,
+						using only the items on this and following lines,
+						but with the item causing the break automatically starting a new line
+						in the <a href="#algo-line-break"> step,
+						then continue with this step.
+						Forced breaks <em>within</em> flexbox items are ignored.
 
-				<li>If size of flexbox in inline direction is not definite, multi-line layout algorithm is run using the set of items 
-				that have fit on the current page.
+				<li>
+					If there are any flexbox items not laid out by the previous step,
+					rerun the flexbox sizing algorithm
+					from <a href="#line-sizing">Line Length Determination</a>
+					through <a href="#main-alignment">Main-Axis Alignment</a>
+					with the next page's size
+					and only the items not already laid out.
+					Return to the previous step,
+					but starting from the first line not already laid out.
 
-				<li>Line packing is done on each page, with content on the page
+				<li>
+					For each fragment of the flexbox,
+					continue the flexbox layout algorithm
+					from <a href="#cross-alignment">Cross Axis Alignment</a>
+					to its finish.
 			</ol>
 	</dl>
 
+	<p class='issue'>
+		I think we need to explicitly handle a definite size in the fragmentation axis,
+		and running out of space.
+		(I think it just lays out as continuous media within the overflow area.)
+
 <h2 id="cssom">CSSOM</h2>
 
 <div class="issue">