[css-grid] track sizing function + sizing function, fix up some flex factor definitions, wordsmith some algorithm bits. hopefully nothing of significance

Author: fantasai

css-grid/Overview.bs

@@ -716,13 +716,15 @@ Track Sizing: the 'grid-template-rows' and 'grid-template-columns' properties</h
 
 	These properties specify,
 	as a space-separated <dfn export>track list</dfn>,
-	the line names and track <a>sizing functions</a> of the <a>grid</a>.
-	Each <dfn export>sizing function</dfn> can be specified as a length,
+	the line names and <a>track sizing functions</a> of the <a>grid</a>.
+	Each <dfn title="track sizing function|sizing function">track sizing function</dfn> can be specified as a length,
 	a percentage of the <a>grid container</a>’s size,
 	a measurement of the contents occupying the column or row,
 	or a fraction of the free space in the grid.
 	It can also be specified as a range using the ''minmax()'' notation,
-	which can combine any of the previously mentioned mechanisms to define a min and max size for the column or row.
+	which can combine any of the previously mentioned mechanisms
+	to specify separate <i title="min track sizing function">min</i>
+	and <i>max track sizing functions</i> for the column or row.
 
 	The 'grid-template-columns' property specifies the <a>track list</a> for the grid's columns,
 	while 'grid-template-rows' specifies the <a>track list</a> for the grid's rows.
@@ -754,7 +756,7 @@ Track Sizing: the 'grid-template-rows' and 'grid-template-columns' properties</h
 		<dt><dfn><<flex>></dfn>
 		<dd>
 			A non-negative dimension with the unit ''fr'' specifying the track's <dfn noexport>flex factor</dfn>.
-			Each <<flex>> value takes a share of the remaining space in proportion to its value.
+			Each <<flex>>-sized track takes a share of the remaining space in proportion to its <i>flex factor</i>.
 			See <a href="#fr-unit">Flexible Lengths</a> for more details.
 
 		<dt><dfn>max-content</dfn>
@@ -774,6 +776,9 @@ Track Sizing: the 'grid-template-rows' and 'grid-template-columns' properties</h
 			and less than or equal to <var>max</var>.
 			If <var>max</var> &lt; <var>min</var>,
 			then <var>max</var> is ignored and ''minmax(min,max)'' is treated as <var>min</var>.
+			As a maximum, a <<flex>> value sets the track's <i>flex factor</i>.
+			As a minimum, it is treated as zero
+			(or ''min-content'', if the <i>grid container</i> is sized under a <i>min-size constraint</i>).
 
 		<dt><dfn>auto</dfn>
 		<dd>
@@ -929,7 +934,7 @@ Flexible Lengths: the ''fr'' unit</h4>
 	A <dfn export>flexible length</dfn> or <dfn><<flex>></dfn> is a dimension with the ''fr'' unit,
 	which represents a fraction of the <a>free space</a> in the <a>grid container</a>.
 
-	The distribution of <a>free space</a> occurs after all non-flexible <a>sizing functions</a> have reached their maximum.
+	The distribution of <a>free space</a> occurs after all non-flexible <a>track sizing functions</a> have reached their maximum.
 	The total size of such rows or columns is subtracted from the available space, yielding the <dfn export>free space</dfn>,
 	which is then divided among the flex-sized rows and columns in proportion to their <i>flex factor</i>.
 
@@ -3303,19 +3308,18 @@ Rewritten Grid Layout Algorithm</h2>
 	Note: We are exploring alternate ways of writing the same algorithm at the moment.
 	All three of these layout algorithms are intended to produce identical results.
 
-	Each track has a <dfn title="minimum track size">minimum</dfn> and
-	a <dfn title="maximum track size">maximum</dfn> <i>sizing function</i>
+	Each track has specified <dfn title="minimum track size">minimum</dfn> and
+	<dfn title="maximum track size">maximum</dfn> <i>sizing functions</i>
 	(which may be the same).
 	Each <i>sizing function</i> is either:
 
 	<ul>
-		<li>A fixed size (<<length>> or resolved <<percentage>>).
-		<li>An intrinsic size (''min-content'' or ''max-content'').
-		<li>A flexible size (<<flex>>).
+		<li>A <dfn>fixed sizing function</dfn> (<<length>> or resolveable <<percentage>>).
+		<li>An <dfn>intrinsic sizing function</dfn> (''min-content'' or ''max-content'').
+		<li>A <dfn>flexible sizing function</dfn> (<<flex>>).
 	</ul>
 
 	The grid layout algorithm defines how to resolve these sizing constraints into used track sizes.
-	The grid items are then laid out into their respective <i>grid areas</i>.
 
 	<ol>
 		<li>First, the <i>track sizing algorithm</i> is used to resolve the sizes of the grid columns.
@@ -3327,7 +3331,14 @@ Rewritten Grid Layout Algorithm</h2>
 				What is this solving and is this the right solution?
 	</ol>
 
-	The remainder of this section is the <dfn>track sizing algorithm</dfn>. There are four steps:
+	Once the size of each <i>grid area</i> is thus established,
+	the <i>grid items</i> are laid out into their respective containing blocks.
+
+	The remainder of this section is the <dfn>track sizing algorithm</dfn>.
+	It calculates from the <i title="min track sizing function">min</i> and <i>max track sizing functions</i>
+	a corresponding <i>minimum track size</i> and <i>maximum track size</i>
+	and finally a used track size.
+	There are four steps:
 	<ol>
 		<li><a href="#init-sizes">Initializing Used Sizes</a>
 		<li><a href="#resolve-intrinsic">Resolving Intrinsic Track Sizes</a>
@@ -3338,40 +3349,54 @@ Rewritten Grid Layout Algorithm</h2>
 <h3 id='init-sizes'>
 Initialize Minimum and Maximum Track Sizes</h3>
 
-	For fixed track sizes,
-	use that resolved size.
+	Since the size contribution of an item to an intrinsically-sized track depends
+	depends on the sizes of any other tracks it spans,
+	each track size is associated with an absolute length as follows
+	before calculating intrinsic sizes:
 
-	For intrinsic track sizes,
-	use an initial <i>minimum track size</i> of zero and an initial <i>maximum track size</i> of infinity.
+	<ul>
+		<li>
+			For fixed track sizes,
+			resolve to an absolute length and use that size.
+		<li>
+			For intrinsic track sizes,
+			use an initial <i>minimum track size</i> of zero and an initial <i>maximum track size</i> of infinity.
 
-    For flexible track sizes,
-	use an initial <i>maximum track size</i> of infinity.
+		<li>
+			For flexible track sizes,
+			use an initial <i>maximum track size</i> of infinity.
+	</ul>
 
-	A flexible <i>minimum track size</i> is treated exactly as a fixed track size of zero;
-    except when the <i>grid container</i> is being sized under a <i>min-content constraint</i>,
+	A track with a flexible <em>minimum</em> <i>sizing function</i>
+	is treated exactly as if it had a fixed <i>min track sizing function</i> of zero;
+	except when the <i>grid container</i> is being sized under a <i>min-content constraint</i>,
 	in which case it is treated exactly as ''min-content''.
 	<span class='issue'>This seems correct, but should be checked because it wasn't in the original algorithm.</span>
 
-	These initial sizes will be resolved in subsequent steps.
-
 <h3 id="resolve-intrinsic">
 Resolve Intrinsic Track Sizes</h3>
 
-	The following steps resolve intrinsic track sizes to used lengths.
+	The following steps resolve intrinsic track sizes to absolute lengths.
 	First it resolves those sizes based on items that are contained wholly within a single track.
 	Then it gradually adds in the space requirements of items that span multiple tracks,
-	evenly increasing their sizes insofar as possible.
+	evenly distributing the extra space across those tracks
+	insofar as possible.
 
 	<ol>
 		<li>
-			For each track with an intrinsic size, consider the items with a span of 1:
+			For each track with an intrinsic <i>track sizing function</i>,
+			consider the items in it with a span of 1:
 			<ul>
-				<li>Set any ''min-content'' track size to the maximum of their <i>min-size contributions</i>.
-				<li>Set any ''max-content'' track size to the maximum of their <i>max-size contributions</i>.
+				<li>
+					If the track has any ''min-content'' <i>sizing functions</i>,
+					set the used size to the maximum of their <i>min-size contributions</i>.
+				<li>
+					If the track has any ''max-content'' <i>sizing functions</i>,
+					set the used size to the maximum of their <i>max-size contributions</i>.
 			</ul>
 		<li>
 			Next, consider the items with a span of 2
-			and that do not span a track with a flexible maximum size:
+			that do not span a track with a <i>flexible sizing function</i>:
 			<ol>
 				<li>
 					First increase any ''min-content'' <i>minimum track sizes</i>