[css2] Added a statement clarifying use of containing block, removed containing block details, removed collapsing margins section, added float details

ianbjacobs · ianbjacobs · commit 746c4a3289da · 1998-03-22T02:14:14.000Z
--HG--
extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%401330
diff --git a/css2/visuren.src b/css2/visuren.src
@@ -1,6 +1,6 @@
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
 <html lang="en">
-<!-- $Id: visuren.src,v 2.35 1998-03-21 23:47:19 ijacobs Exp $ -->
+<!-- $Id: visuren.src,v 2.36 1998-03-22 02:14:14 ijacobs Exp $ -->
 <HEAD>
 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 <TITLE>Visual rendering model</TITLE>
@@ -81,21 +81,21 @@ several views of a document.
 of a rectangular box called a <span class="index-def"
 title="containing block"><dfn>containing block</dfn></span>.  A box
 establishes reference edges for its descendants and is itself
-positioned with respect to its containing block. A box is not confined
-by its containing block -- it is positioned with respect to its edges
-and may even <a href="visufx.html#overflow">overflow</a> those
-edges. When a box is <a href="#floats">floated</a> inside a containing
+positioned with respect to its containing block. The phrase "a box's
+containing block" means "the containing block in which the box lives",
+not the one it generates.
+
+<P>Each box is positioned with respect to its containing block, but it
+is not confined by this containing block (it may <a
+href="visufx.html#overflow">overflow</a>)
+
+<P>When a box is <a href="#floats">floated</a> inside a containing
 block, layout of boxes in the containing block is also affected by the
 edges of those floating boxes.
 
 <!-- The above may not be true: inline elements can establish
 non-rectangular containing blocks according to the WG -IJ -->
 
-<H4>Containing block details</h4>
-
-<P><em>This section describes the details of how a containing block
-is determined. It may be skipped during a first reading.</em>
-
 <P>The root of the <a href="conform.html#doctree">document tree</a>
 generates a box that serves as the <span class="index-def"
 title="initial containing block|containing block::initial"><a
@@ -112,55 +112,9 @@ class="propinst-position">'position'</span> property) or floated
 (i.e., user agents <a href="syndata.html#ignore">ignore</a> the <span
 class="propinst-float">'float'</span> property).
 
-<P>The containing block for a box other than the root box determined
-as follows:</p>
-
-<ul>
-<li>If the value of the <span
-class="propinst-position">'position'</span> property for the parent
-element is anything but 'static' then the containing block is established
-by the parent box.
-<li>Otherwise, if the value of the <span
-class="propinst-display">'display'</span> property for the parent
-element is anything but 'inline' then the containing block is
-established by the parent box.
-<li>Otherwise, the containing block is the parent's containing block.
-</ul>
-
-<P>When the containing block is established by a <a
-href="#block-box">block</a> box, it has the same
-width, height, and position as the parent's <a
-href="box.html#padding-edge">padding edge</a>. The edges
-are called the top, bottom, left, and right of the containing block.
-
-<P>When the containing block is established by an <a
-href="#inline-level">inline-level</a> element, it has the same width,
-height, and position as the <a
-href="box.html#padding-edge">padding edge</a> of the first (in the
-source tree) box generated by the inline-level element.
-
-<!-- The previous paragraph does not comply with the WG's decision
-in. Note, especially, in WG solution, that percentages applied to
-negative widths cause problems. -IJ -->
-
-<P><a href="#relative-positioning">Relatively
-positioned</a> <a href="#inline-box">inline</a> boxes must be
-considered specially since (1) the <a
-href="conform.html#rendered-content">rendered content</a> of an inline-level
-element may not be rectangular in shape but (2) a relatively
-positioned box establishes a new containing block and containing
-blocks must be rectangular. The reference edges for descendants
-are the following:</p>
-
-<ul>
-<li>For left-to-right scripts, the left and top edges are those
-of the first inline box. The bottom and right edges are those
-of the last inline box.
-<li>For right-to-left scripts, the right and top edges are those
-of the first inline box. The bottom and left edges are those
-of the last inline box.
-</ul>
-
+<P>The <a href="visudet.html#containing-block-details">details</a> of
+how a containing block's dimensions are calculated are described in
+the <a href="visudet.html">next chapter</a>.
 
 <H2><a name="box-gen">Controlling box generation</a></h2>
 
@@ -528,7 +482,8 @@ following box</a> is established independently of the offset.
 <dd> The box coordinates (and possibly size) are calculated 
 in <a href="#absolute-positioning">absolute</a> terms
 with respect to the box's <a
-href="#containing-block">containing block</A>.
+href="#containing-block">containing block</A>. Absolutely
+positioned boxes are taken out of the normal flow.
 
 <dt><strong>fixed</strong>
 <dd> The box coordinates are calculated according to the 'absolute'
@@ -630,7 +585,7 @@ these properties).
 <P>Absolutely positioned boxes have padding, borders, and margins.
 Margins of absolutely positioned boxes do not 
 <a
-href="./visudet.html#collapsing-margins">collapse</a>.
+href="box.html#collapsing-margins">collapse</a>.
 
 <P>For more information about the width and height of boxes, please
 consult the sections on <a href="visudet.html#box-width">box width
@@ -718,7 +673,7 @@ other, vertically, beginning at the top of a containing block. The
 vertical distance between two sibling boxes is determined by the <span
 class="propinst-margin">'margin'</span> properties. Vertical margins
 between adjacent block boxes <a
-href="./visudet.html#collapsing-margins">collapse</a>.
+href="box.html#collapsing-margins">collapse</a>.
 
 <!-- Add a statement/link here about bottom-up height calc? -IJ -->
 
@@ -954,7 +909,7 @@ explicitly.
 positioning boxes on the same lines as the float. The outer edge of a
 float becomes the current edge for flowed or floated boxes to the left
 or right side.  The margins of floating boxes never <a
-href="visudet.html#collapsing-margins">collapse</a> with margins of
+href="box.html#collapsing-margins">collapse</a> with margins of
 adjacent boxes.
 
 <P>The values of this property have the following meanings:</p>
@@ -1017,7 +972,7 @@ The following HTML source:
 
 <P>Note that the margin of the P element encloses the floating
 IMG element and that the vertical margins do not 
-<a href="./visudet.html#collapsing-margins">collapse</a>.
+<a href="box.html#collapsing-margins">collapse</a>.
 </div>
 
 <H3>Controlling flow next to floats</H3> 
@@ -1070,9 +1025,52 @@ the element in the <a href="conform.html#doctree">document tree</a>
 that generated B.
 </ul>
 
-<P>Please consult the section on <a
-href="visudet.html#floating-constraints">floating constraints</a> for
-additional constraints.
+<P>Furthermore:</p>
+
+<OL>
+<LI> The left <a href="box.html#outer-edge">outer edge</a> of a
+left-floating box may not be to the left of the left edge of its <a
+href="visuren.html#containing-block">containing block</a>. Analogous rules hold
+for right-floating elements.
+
+<LI> The left <a href="box.html#outer-edge">outer edge</a> of a
+left-floating box must be to the right of the right <a
+href="box.html#outer-edge">outer edge</a> of every <a
+href="visuren.html#preceding-box">preceding</a> left-floating box or the
+top of the former must be lower than the bottom of the
+latter. Analogous rules hold for right-floating boxes.
+
+<LI>The right <a href="box.html#outer-edge">outer edge</a> of a
+left-floating box may not be to the right of the left <a
+href="box.html#outer-edge">outer edge</a> of any right-floating
+box that is to the right of it. Analogous rules hold for
+right-floating elements.
+
+<LI>A floating box's <a href="box.html#outer-edge">outer top</a>
+may not be higher than the top of its <a
+href="visuren.html#containing-block">containing block</a>.
+
+<LI> The <a href="box.html#outer-edge">outer top</a> of an
+element's floating box may not be higher than the outer top of any <a
+href="visuren.html#block-box">block</a> or <a
+href="visuren.html#floats">floated</a> box generated by a <a
+href="conform.html#preceding">preceding</a> element.
+
+<LI>The <a href="box.html#outer-edge">outer top</a> of an
+element's floating box may not be higher than the top of any <span
+class="index-inst" title="line-box"><a
+href="visuren.html#line-box">line-box</a></span> containing a box
+generated by a <a href="conform.html#preceding">preceding</a> element.
+
+<LI> A floating box must be placed as high as possible.
+
+<LI> A left-floating box must be put as far to the left as
+possible, a right-floating box as far to the right as possible. A
+higher position is preferred over one that is further to the
+left/right.
+</OL>
+
+<!-- Please verify use of preceding or preceding box here. -IJ -->
 
 
 <H2><a name="absolute-positioning">Absolute positioning</a></H2>
@@ -1104,7 +1102,7 @@ established by the <a href="#viewport">viewport</A>.
 <P>For <a href="media.html#continuous-media-group">continuous
 media</a>, fixed boxes do not move when the document is scrolled. In
 this respect, they are similar to <a
-href="./colors.html#background-properties">fixed background
+href="colors.html#background-properties">fixed background
 images</a>.
 
 <P>For <a href="page.html">paged media</a>, boxes with fixed
