[css-sizing] Make Sizing depend on 2.1 floating behavior rather than trying to define it here.

Author: fantasai

css-sizing-3/Overview.bs

@@ -264,8 +264,12 @@ New Keywords for 'width' and 'height'</h3>
 			as appropriate to the writing mode.
 	</dl>
 
+	Issue: Is ''fill'' stable enough or should we defer to L4?
+	Is the name clear enough, or should it be reverted to ''fill-available''
+	(or changed to something else)?
+
 	Note: To size an element such that it avoids overlapping sibling floats,
-	make sure it's a <a>formatting context</a>.
+	make sure it's a <a>formatting context</a> root.
 	For some layout modes, such as Grid and Flexbox,
 	this is true automatically.
 	For Block layout, this means using ''display: flow-root;''.
@@ -343,188 +347,36 @@ Intrinsic Sizes of Replaced Elements</h3>
 		of the element,
 		calculated with an unconstrained specified size.
 
-	The <a>min-content contribution</a> and <a>max-content contribution</a> in each axis
-	is the element's specified outer size in that axis, if definite;
-	otherwise, they are the <a>min-content size</a>, as specified above,
-	plus the element's margin/border/padding in that axis,
-	clamped by the element's min and max size properties in that axis.
-
 <h3 id='inline-intrinsic'>
-Intrinsic Sizes of Non-Replaced Inlines</h3>
-
-	<p>
-		The <a>min-content inline size</a> of an inline box
-		is the length of the largest unbreakable sequence of inline content.
-		The <a>min-content inline-size contribution</a> of an inline box
-		is its <a>min-content inline size</a>,
-		plus any <a>inline-axis</a> margin, border, and padding
-		adjacent to that sequence.
-
-	<p>
-		The <a>max-content inline size</a> of an inline box
-		is the length of the largest sequence of inline content
-		on a single line
-		when only forced line breaks are taken.
-		The <a>max-content inline-size contribution</a> of an inline box
-		is its <a>max-content inline size</a>,
-		plus any <a>inline-axis</a> margin, border, and padding
-		adjacent to that sequence.
-
-	<p>
-		The <a>min-content block size</a>, <a>max-content block size</a>, <a>min-content block-size contribution</a>, and <a>max-content block-size contribution</a> of an inline box
-		are the distance from the head edge of the first line box
-		to the foot edge of the last line box
-		on which the inline appears.
-
-<h3 id='block-intrinsic'>
-Intrinsic Sizes of Non-Replaced Blocks</h3>
-
-	<p>
-		The <a>min-content inline size</a> of a <a>block container box</a>
-		is the largest <a>min-content inline-size contribution</a>
-		of its in-flow or floated children.
-
-	<p>
-		The <a>max-content inline size</a> of a <a>block container box</a>
-		is the inline-size of the box after layout,
-		if all children are sized under a <a>max-content constraint</a>.
-	<p>
-		If the computed inline-size of a <a>block-level box</a>
-		is ''width/min-content'', ''width/max-content'', or a <a>definite size</a>,
-		its <a>min-content inline-size contribution</a>
-		is that size
-		plus any <a>inline-axis</a> margin, border, and padding.
-		Otherwise, if the computed inline-size of the block is ''width/fit-content'', ''width/auto'', or ''width/fill'',
-		its <a>min-content inline-size contribution</a>
-		is its <a>min-content inline size</a>
-		plus any <a>inline-axis</a> margin, border, and padding.
-
-	<p>
-		If the computed inline-size of a <a>block-level box</a>
-		is ''width/min-content'', ''width/max-content'', or a <a>definite size</a>,
-		its <a>max-content inline-size contribution</a>
-		is that size
-		plus any <a>inline-axis</a> margin, border, and padding.
-		Otherwise, if the computed inline-size of the block is ''width/fit-content'', ''width/auto'', or ''width/fill'',
-		its <a>max-content inline-size contribution</a>
-		is its <a>max-content inline size</a>
-		plus any <a>inline-axis</a> margin, border, and padding.
-
-	<p>
-		The <a>min-content block size</a> and <a>max-content block size</a> of a <a>block container box</a>
-		is the content block-size as defined
-		(for horizontal writing modes)
-		in <a href="https://www.w3.org/TR/CSS21/visudet.html#normal-block">CSS2.1§10.6.3</a>
-		and <a href="https://www.w3.org/TR/CSS21/tables.html#height-layout">CSS2.1§17.5.3</a>
-		for elements with ''height: auto'',
-		and analogously for vertical writing modes.
-
-	<p>
-		The <a>min-content block-size contribution</a> and <a>max-content block-size contribution</a> of a <a>block-level box</a>
-		is the block-size of the block after layout,
-		plus any <a>block-axis</a> margin, border, and padding.
-
-	Issue: Need to handle floats.
-	See <a href="https://lists.w3.org/Archives/Public/www-style/2014Oct/0061.html">Greg's issue</a>
-	and <a href="https://lists.w3.org/Archives/Public/www-style/2014Nov/0085.html">dbaron's response</a>.
+Intrinsic Sizes of Other Boxes</h3>
 
-<h3 id='table-intrinsic'>
-Intrinsic Sizes in Table Layout</h3>
+	The <a>min-content size</a> of a box is the size it would have as an
+	''width/auto''-sized float in a zero-sized containing block.
+	(In other words, the minimum size it has when sized as “shrink-to-fit”.)
 
-	<p class='issue'>
-		???
-
-
-
-<h3 id="multicol-intrinsic">
-Intrinsic Sizes in Multi-column Layout</h3>
-
-
-<h4 id="multicol-min-content">
-Min-content Sizes in Multi-column Layout</h3>
-
-	<p>
-		The <a>min-content inline size</a> of a multi-column element
-		with a computed 'column-width' not ''column-width/auto''
-		is the smaller of
-		its 'column-width'
-		and the largest <a>min-content inline-size contribution</a> of its contents.
-
-	<p>
-		The <a>min-content inline size</a> of a multi-column element
-		with a computed 'column-width' of ''column-width/auto''
-		is the largest <a>min-content inline-size contribution</a> of its contents
-		multiplied by its 'column-count'
-		(treating ''column-count/auto'' as ''1'').
-
-<h4 id="multicol-max-content">
-Max-content Sizes in Unconstrained-height Multi-column Layout</h3>
+	The <a>max-content size</a> of a box is the size it would have as an
+	''width/auto''-sized float in an infinitely-sized containing block.
+	(In other words, the maximum size it has when sized as “shrink-to-fit”.)
 
-	<p>
-		The <a>max-content inline size</a> of a multi-column element
-		with unrestrained column heights
-		and a computed 'column-count' not ''column-count/auto''
-		is its 'column-count'
-		multiplied by the larger of
-		its 'column-width' (treating ''column-width/auto'' as zero)
-		and the largest <a>min-content inline-size contribution</a> of its contents.
-
-	<p class="note">
-		Note that the contents of the multi-column element
-		can still grow to be wider and shorter
-		if the resulting column width is still smaller
-		than the largest <a>max-content inline-size contribution</a> of its contents.
-
-	<p>
-		The <a>max-content inline size</a> of a multi-column element
-		with unrestrained column heights
-		and a computed 'column-count' of ''column-count/auto''
-		is its 'column-width'
-		multiplied by the number of columns obtained by taking all allowed column breaks [[CSS3-BREAK]].
-
-	<!--
-	The above was decided based on dholbert's example in http://lists.w3.org/Archives/Public/www-style/2012Oct/0017.html .
-	These definitions make multicols work well in flexbox,
-	both in ''stretch'' and non-''stretch'' cases,
-	without wasted space or needless overflow.
-	-->
-
-<h4 id="multicol-max-content-restrained">
-Max-content Sizes in Constrained-height Multi-column Layout</h3>
+	Note: This specification does not define how to determine these sizes.
+	Please refer to [[CSS21]],
+	the relevant CSS specification for that display type,
+	and/or existing implementations
+	for further details.
 
-	<p>
-		The <a>max-content inline size</a> of a multi-column element
-		with restrained-height columns (i.e. a specified 'height' or 'max-height', or whichever properties map to the <a>block size</a> of the element)
-		is the <a>inline size</a> that would exactly include all of its columns.
-		It may be approximated by:
+<h3 id="intrinsic-contribution">
 
-	<ul>
-		<li>
-			Laying out the element with column-spanning elements given ''display: none'',
-			and taking a inline-size that includes all the columns.
-
-		<li>
-			Laying out all of the column-spanning elements into that resulting inline-size,
-			and taking the resulting block-size.
-
-		<li>
-			Subtracting that resulting block-size from the specified restraint,
-			laying out the element without column-spanning elements again into this adjusted block-size,
-			and taking the inline-size of all its columns as its <a>max-content inline size</a>.
-	</ul>
+	A box’s <a>min-content contribution</a>/<a>max-content contribution</a> in each axis
+	is the size of the content box
+	of a hypothetical ''width/auto''-sized float
+	that contains only that box,
+	if that hypothetical float's containing block is zero-sized/infinitely-sized.
 
-	<p>
-		or by some more accurate method.
-
-	<p class='note'>
-		This approximation can result in some slack,
-		but avoids overflow in the most common cases,
-		where the balanced height of the columns above spanning elements are approximately equal.
-
-	<p class='note'>
-		In the common case of no column-spanning elements,
-		this approximation collapses to simply doing a layout,
-		and measuring the resulting columns.
+	Note: This specification does not define how to determine these sizes.
+	Please refer to [[CSS21]],
+	the relevant CSS specification for that display type,
+	and/or existing implementations
+	for further details.
 
 <h2 id='extrinsic'>
 Extrinsic Size Determination</h2>
@@ -582,19 +434,11 @@ Fill-available Sizing</h3>
 Changes</h2>
 
 	<p>
-		Changes since the <a href="https://www.w3.org/TR/2012/WD-css3-sizing-20120927/">September 2012 Working Draft</a> include:
+		Changes since the INSERT DATED DRAFT HERE AFTER PUBLISHING A NEW OLD ONE.
 
 	<ul>
-		<li>Changed <code>fill-available</code> keyword to <code>fill</code>.
-		<li>Hooked up intrinsic sizes of replaced elements to the <a>default sizing algorithm</a> in [[!CSS3-IMAGES]].
-		<li>Specified that <a>extrinsic sizing</a> treates ''margin/auto'' margins as zero.
-		<li>Clarified definition of <a>available size</a>.
-		<li>Specified that percentages resolved against an intrinsic size of the parent computes falls back to auto sizing.
-		<li>Fixed bad wording wrt containing blocks in <a>fill-available inline size</a> definition,
-		    and specified that it is calculated <em>after</em> margin collapsing.
-		<li>Specified that an absolutely-positioned box's containing block is always considered definite.
-		<li>Improved section on intrinsic sizing of multi-column elements.
-		<li>Cleaned up some terminology (“min-size” to “min-content size”, “measure” to “inline-size, “extent” to “block-size”).
+		<li>Removed normative definitions of the various sizes, deferring to CSS2.1's “undefined” for floats.
+		(We will restore these details in a Level 4 draft.)
 	</ul>
 
 <h2 class=no-num id="acknowledgments">