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[giow] (0) Define an API to clear all the hit regions, for authors wh…
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…o don't need to use clearRect() since everything they paint is opaque.

Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=26404
Affected topics: Canvas

git-svn-id: http://svn.whatwg.org/webapps@8747 340c8d12-0b0e-0410-8428-c7bf67bfef74
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Hixie committed Sep 4, 2014
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Expand Up @@ -46067,6 +46067,7 @@ <h5 id=2dcontext>4.12.4.2 The 2D rendering context</h5>
// hit regions
void <a href=#dom-context-2d-addhitregion id=2dcontext:dom-context-2d-addhitregion>addHitRegion</a>(optional <a href=#hitregionoptions id=2dcontext:hitregionoptions>HitRegionOptions</a> options);
void <a href=#dom-context-2d-removehitregion id=2dcontext:dom-context-2d-removehitregion>removeHitRegion</a>(DOMString id);
void <a href=#dom-context-2d-clearhitregions id=2dcontext:dom-context-2d-clearhitregions>clearHitRegions</a>();

// <a href=#pixel-manipulation id=2dcontext:pixel-manipulation>pixel manipulation</a>
<a href=#imagedata id=2dcontext:imagedata>ImageData</a> <a href=#dom-context-2d-createimagedata id=2dcontext:dom-context-2d-createimagedata>createImageData</a>(double sw, double sh);
Expand Down Expand Up @@ -48729,6 +48730,10 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
same pixels before the removed regions were added, overlapping them, do not resume their
previous role.</p>

<dt><var>context</var> . <code id=hit-regions:dom-context-2d-clearhitregions><a href=#dom-context-2d-clearhitregions>clearHitRegions</a></code>()<dd>

<p>Removes all hit regions from the canvas bitmap.</p>

</dl>


Expand Down Expand Up @@ -48943,6 +48948,10 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
one.<li><p><a href=#garbage-collect-the-regions id=hit-regions:garbage-collect-the-regions-2>Garbage-collect the regions</a> of the rendering context's <a href=#scratch-bitmap id=hit-regions:scratch-bitmap-8>scratch
bitmap</a>.</ol>

<p>When the <dfn id=dom-context-2d-clearhitregions><code>clearHitRegions()</code></dfn>
method is invoked, the user agent must remove all the <a href=#hit-region id=hit-regions:hit-region-21>hit regions</a>
from the rendering context's <a href=#scratch-bitmap id=hit-regions:scratch-bitmap-9>scratch bitmap</a>'s <a href=#hit-region-list id=hit-regions:hit-region-list-10>hit region list</a>.</p>



<hr>
Expand All @@ -48959,7 +48968,7 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>

<dl class=domintro><dt><var>event</var> . <code id=hit-regions:dom-mouseevent-region-3><a href=#dom-mouseevent-region>region</a></code><dd>

<p>If the mouse was over a <a href=#hit-region id=hit-regions:hit-region-21>hit region</a>, then this returns the <a href="#hit-region's-id" id="hit-regions:hit-region's-id-4">hit region's
<p>If the mouse was over a <a href=#hit-region id=hit-regions:hit-region-22>hit region</a>, then this returns the <a href="#hit-region's-id" id="hit-regions:hit-region's-id-4">hit region's
ID</a>, if it has one.</p>

<p>Otherwise, returns null.</p>
Expand All @@ -48986,8 +48995,8 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
requirements not been applied.</p>

<ol><li><p>If the pointing device is not indicating a pixel on the <code id=hit-regions:the-canvas-element-15><a href=#the-canvas-element>canvas</a></code>, then act as
normal and abort these steps.<li><p>If the <code id=hit-regions:the-canvas-element-16><a href=#the-canvas-element>canvas</a></code> element has no <a href=#hit-region-list id=hit-regions:hit-region-list-10>hit region list</a>, then act as normal
and abort these steps.<li><p>Let <var>pixel</var> be the pixel indicated by the pointing device.<li><p>Let <var>region</var> be the <a href=#hit-region id=hit-regions:hit-region-22>hit region</a> that is <a href=#the-region-for-a-pixel id=hit-regions:the-region-for-a-pixel>the region for the pixel</a> <var>pixel</var> on this
normal and abort these steps.<li><p>If the <code id=hit-regions:the-canvas-element-16><a href=#the-canvas-element>canvas</a></code> element has no <a href=#hit-region-list id=hit-regions:hit-region-list-11>hit region list</a>, then act as normal
and abort these steps.<li><p>Let <var>pixel</var> be the pixel indicated by the pointing device.<li><p>Let <var>region</var> be the <a href=#hit-region id=hit-regions:hit-region-23>hit region</a> that is <a href=#the-region-for-a-pixel id=hit-regions:the-region-for-a-pixel>the region for the pixel</a> <var>pixel</var> on this
<code id=hit-regions:the-canvas-element-17><a href=#the-canvas-element>canvas</a></code> element's bitmap, if any.<li><p>If there is no <var>region</var>, then act as normal and abort these
steps.<li><p>Let <var>id</var> be the <var>region</var>'s <a href="#hit-region's-id" id="hit-regions:hit-region's-id-6">ID</a>, if any.<li><p>If there is an <var>id</var>, then initialise the event object's <code id=hit-regions:dom-mouseevent-region-4><a href=#dom-mouseevent-region>region</a></code> attribute to <var>id</var>.<li><p>Let <var>control</var> be the <a href=#the-control-represented-by-a-region id=hit-regions:the-control-represented-by-a-region>control represented by</a> <var>region</var> for this <code id=hit-regions:the-canvas-element-18><a href=#the-canvas-element>canvas</a></code>
element, if any.<li><p>If there is a <var>control</var>, then target the event object at <var>control</var> instead of the <code id=hit-regions:the-canvas-element-19><a href=#the-canvas-element>canvas</a></code> element.<li><p>Continue dispatching the event, but with the updated event object and target as given in
Expand All @@ -49005,7 +49014,7 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>

<dl class=domintro><dt><var>touch</var> . <code id=hit-regions:dom-touch-region-2><a href=#dom-touch-region>region</a></code><dd>

<p>If the <a href=#touch-point id=hit-regions:touch-point>touch point</a> was over a <a href=#hit-region id=hit-regions:hit-region-23>hit region</a> when it was first placed
<p>If the <a href=#touch-point id=hit-regions:touch-point>touch point</a> was over a <a href=#hit-region id=hit-regions:hit-region-24>hit region</a> when it was first placed
on the surface, then this returns the <a href="#hit-region's-id" id="hit-regions:hit-region's-id-7">hit region's ID</a>, if it has one.</p>

<p>Otherwise, returns null.</p>
Expand All @@ -49020,9 +49029,9 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
surface: <a href=#refsTOUCH>[TOUCH]</a></p>

<ol><li><p>If the <a href=#touch-point id=hit-regions:touch-point-3>touch point</a> is not on a pixel on the <code id=hit-regions:the-canvas-element-20><a href=#the-canvas-element>canvas</a></code>, then return
null and abort these steps.<li><p>If the <code id=hit-regions:the-canvas-element-21><a href=#the-canvas-element>canvas</a></code> element has no <a href=#hit-region-list id=hit-regions:hit-region-list-11>hit region list</a>, then return null
null and abort these steps.<li><p>If the <code id=hit-regions:the-canvas-element-21><a href=#the-canvas-element>canvas</a></code> element has no <a href=#hit-region-list id=hit-regions:hit-region-list-12>hit region list</a>, then return null
and abort these steps.<li><p>Let <var>pixel</var> be the pixel that the <a href=#touch-point id=hit-regions:touch-point-4>touch point</a> is
on.<li><p>Let <var>region</var> be the <a href=#hit-region id=hit-regions:hit-region-24>hit region</a> that is <a href=#the-region-for-a-pixel id=hit-regions:the-region-for-a-pixel-2>the region for the pixel</a> <var>pixel</var> on this
on.<li><p>Let <var>region</var> be the <a href=#hit-region id=hit-regions:hit-region-25>hit region</a> that is <a href=#the-region-for-a-pixel id=hit-regions:the-region-for-a-pixel-2>the region for the pixel</a> <var>pixel</var> on this
<code id=hit-regions:the-canvas-element-22><a href=#the-canvas-element>canvas</a></code> element's bitmap, if any.<li><p>If there is no <var>region</var>, then return null and abort these
steps.<li><p>Let <var>id</var> be the <var>region</var>'s <a href="#hit-region's-id" id="hit-regions:hit-region's-id-8">ID</a>, if any, or else null.<li><p>Return <var>id</var>.</ol>

Expand All @@ -49040,17 +49049,17 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
<hr>

<p>User agents are encouraged to make use of the information present in a <code id=hit-regions:the-canvas-element-25><a href=#the-canvas-element>canvas</a></code>
element's <a href=#hit-region-list id=hit-regions:hit-region-list-12>hit region list</a> to improve the accessibility of <code id=hit-regions:the-canvas-element-26><a href=#the-canvas-element>canvas</a></code>
element's <a href=#hit-region-list id=hit-regions:hit-region-list-13>hit region list</a> to improve the accessibility of <code id=hit-regions:the-canvas-element-26><a href=#the-canvas-element>canvas</a></code>
elements.</p>

<p>Each <a href=#hit-region id=hit-regions:hit-region-25>hit region</a> should be handled in a fashion equivalent to a node in a virtual
<p>Each <a href=#hit-region id=hit-regions:hit-region-26>hit region</a> should be handled in a fashion equivalent to a node in a virtual
DOM tree rooted at the <code id=hit-regions:the-canvas-element-27><a href=#the-canvas-element>canvas</a></code> element. The hierarchy of this virtual DOM tree must
match the hierarchy of the <a href=#hit-region id=hit-regions:hit-region-26>hit regions</a>, as described by the <a href="#hit-region's-parent" id="hit-regions:hit-region's-parent-12">parent</a> of each region. Regions without a <a href="#hit-region's-parent" id="hit-regions:hit-region's-parent-13">parent</a> must be treated as children of the <code id=hit-regions:the-canvas-element-28><a href=#the-canvas-element>canvas</a></code> element for
match the hierarchy of the <a href=#hit-region id=hit-regions:hit-region-27>hit regions</a>, as described by the <a href="#hit-region's-parent" id="hit-regions:hit-region's-parent-12">parent</a> of each region. Regions without a <a href="#hit-region's-parent" id="hit-regions:hit-region's-parent-13">parent</a> must be treated as children of the <code id=hit-regions:the-canvas-element-28><a href=#the-canvas-element>canvas</a></code> element for
the purpose of this virtual DOM tree. For each node in such a DOM tree, the <a href="#hit-region's-bounding-circumference" id="hit-regions:hit-region's-bounding-circumference-2">hit region's
bounding circumference</a> gives the region of the screen to use when representing the node (if
appropriate).</p>

<p>The semantics of a <a href=#hit-region id=hit-regions:hit-region-27>hit region</a> for the purposes of this virtual DOM tree are those
<p>The semantics of a <a href=#hit-region id=hit-regions:hit-region-28>hit region</a> for the purposes of this virtual DOM tree are those
of the <a href=#the-control-represented-by-a-region id=hit-regions:the-control-represented-by-a-region-2>the control represented by the
region</a>, if it has one, or else of a non-interactive element whose ARIA role, if any, is
that given by the <a href="#hit-region's-aria-role" id="hit-regions:hit-region's-aria-role-3">hit region's ARIA role</a>, and whose textual representation, if any,
Expand All @@ -49062,7 +49071,7 @@ <h6 id=hit-regions>4.12.4.2.15 Hit regions</h6>
element's bitmap, then the element's position relative to the document should be presented as if
it was that region in the <code id=hit-regions:the-canvas-element-31><a href=#the-canvas-element>canvas</a></code> element's virtual DOM tree.</p>

<p>The semantics of a <a href=#hit-region id=hit-regions:hit-region-28>hit region</a> for the purposes of this virtual DOM tree are those
<p>The semantics of a <a href=#hit-region id=hit-regions:hit-region-29>hit region</a> for the purposes of this virtual DOM tree are those
of the <a href=#the-control-represented-by-a-region id=hit-regions:the-control-represented-by-a-region-3>the control represented by the
region</a>, if it has one, or else of a non-interactive element whose ARIA role, if any, is
that given by the <a href="#hit-region's-aria-role" id="hit-regions:hit-region's-aria-role-4">hit region's ARIA role</a>, and whose textual representation, if any,
Expand Down

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