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skia2/site/user/api/SkAutoCanvasRestore_Reference.md
Cary Clark 224c700a1f sync docs up with tip of tree 
Also check in work in progress for blend modes,
round rects, and a placeholder for pictures.

One minor include change to add a parameter name
for SkBlendMode function.

TBR=reed@google.com
R=caryclark@google.com

Docs-Preview: https://skia.org/?cl=134200
Bug: skia:6898
Change-Id: I5d2a9221d61edb32d9c7edbb3193401605b2b513
Reviewed-on: https://skia-review.googlesource.com/134200
Reviewed-by: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
2018-06-27 15:47:45 +00:00

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SkAutoCanvasRestore Reference
===
# <a name='Automatic_Canvas_Restore'>Automatic Canvas Restore</a>
# <a name='SkAutoCanvasRestore'>Class SkAutoCanvasRestore</a>
Stack helper class calls <a href='SkCanvas_Reference#SkCanvas_restoreToCount'>SkCanvas::restoreToCount</a> when <a href='#SkAutoCanvasRestore'>SkAutoCanvasRestore</a>
goes out of scope. Use this to guarantee that the canvas is restored to a known
state.
## Overview
<table style='border-collapse: collapse; width: 62.5em'>
<tr><th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Topic</th>
<th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Description</th></tr>
<tr style='background-color: #f0f0f0; '>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '><a href='#Constructor'>Constructors</a></td>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>functions that construct <a href='#SkAutoCanvasRestore'>SkAutoCanvasRestore</a></td>
</tr>
<tr>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '><a href='#Member_Function'>Functions</a></td>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>global and class member functions</td>
</tr>
</table>
## <a name='Constructor'>Constructor</a>
SkAutoCanvasRestore can be constructed or initialized by these functions, including C++ class constructors.
<table style='border-collapse: collapse; width: 62.5em'>
<tr><th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Topic</th>
<th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Description</th></tr>
<tr style='background-color: #f0f0f0; '>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '><a href='#SkAutoCanvasRestore_SkCanvas_star'>SkAutoCanvasRestore(SkCanvas* canvas, bool doSave)</a></td>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>preserves <a href='SkCanvas_Reference#Canvas'>Canvas</a> save count</td>
</tr>
<tr>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '><a href='#SkAutoCanvasRestore_destructor'>~SkAutoCanvasRestore()</a></td>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>restores <a href='SkCanvas_Reference#Canvas'>Canvas</a> to saved state</td>
</tr>
</table>
## <a name='Member_Function'>Member Function</a>
SkAutoCanvasRestore member functions read and modify the structure properties.
<table style='border-collapse: collapse; width: 62.5em'>
<tr><th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Topic</th>
<th style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>Description</th></tr>
<tr style='background-color: #f0f0f0; '>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '><a href='#SkAutoCanvasRestore_restore'>restore</a></td>
<td style='text-align: left; border: 2px solid #dddddd; padding: 8px; '>restores <a href='SkCanvas_Reference#Canvas'>Canvas</a> to saved state</td>
</tr>
</table>
<a name='SkAutoCanvasRestore_SkCanvas_star'></a>
## SkAutoCanvasRestore
<pre style="padding: 1em 1em 1em 1em; width: 62.5em;background-color: #f0f0f0">
<a href='#SkAutoCanvasRestore'>SkAutoCanvasRestore</a>(<a href='SkCanvas_Reference#SkCanvas'>SkCanvas</a>* canvas, bool doSave)
</pre>
Preserves <a href='SkCanvas_Reference#Canvas'>Canvas</a> save count. Optionally saves <a href='SkCanvas_Reference#Clip'>Canvas Clip</a> and <a href='SkCanvas_Reference#Matrix'>Canvas Matrix</a>.
### Parameters
<table> <tr> <td><a name='SkAutoCanvasRestore_SkCanvas_star_canvas'><code><strong>canvas</strong></code></a></td>
<td><a href='SkCanvas_Reference#Canvas'>Canvas</a> to guard</td>
</tr>
<tr> <td><a name='SkAutoCanvasRestore_SkCanvas_star_doSave'><code><strong>doSave</strong></code></a></td>
<td>call <a href='SkCanvas_Reference#SkCanvas_save'>SkCanvas::save()</a></td>
</tr>
</table>
### Return Value
utility to restore <a href='SkCanvas_Reference#Canvas'>Canvas</a> state on destructor
### Example
<div><fiddle-embed name="466ef576b88e29d7252422db7adeed1c"></fiddle-embed></div>
### See Also
<a href='SkCanvas_Reference#SkCanvas_save'>SkCanvas::save</a> <a href='SkCanvas_Reference#SkCanvas_restore'>SkCanvas::restore</a>
---
<a name='SkAutoCanvasRestore_destructor'></a>
## ~SkAutoCanvasRestore
<pre style="padding: 1em 1em 1em 1em; width: 62.5em;background-color: #f0f0f0">
<a href='#SkAutoCanvasRestore_destructor'>~SkAutoCanvasRestore</a>()
</pre>
Restores <a href='SkCanvas_Reference#Canvas'>Canvas</a> to saved state. <a href='undocumented#Destructor'>Destructor</a> is called when container goes out of
scope.
### See Also
<a href='SkCanvas_Reference#SkCanvas_save'>SkCanvas::save</a> <a href='SkCanvas_Reference#SkCanvas_restore'>SkCanvas::restore</a>
---
<a name='SkAutoCanvasRestore_restore'></a>
## restore
<pre style="padding: 1em 1em 1em 1em; width: 62.5em;background-color: #f0f0f0">
void <a href='#SkAutoCanvasRestore_restore'>restore</a>()
</pre>
Restores <a href='SkCanvas_Reference#Canvas'>Canvas</a> to saved state immediately. Subsequent calls and
<a href='#SkAutoCanvasRestore_destructor'>~SkAutoCanvasRestore</a> have no effect.
### Example
<div><fiddle-embed name="9f459b218ec079c1ada23f4412968f9a">
#### Example Output
~~~~
saveCanvas: false before restore: 2
saveCanvas: false after restore: 2
saveCanvas: true before restore: 2
saveCanvas: true after restore: 2
saveCanvas: false before restore: 2
saveCanvas: false after restore: 1
saveCanvas: true before restore: 2
saveCanvas: true after restore: 1
final count: 1
~~~~
</fiddle-embed></div>
### See Also
<a href='SkCanvas_Reference#SkCanvas_save'>SkCanvas::save</a> <a href='SkCanvas_Reference#SkCanvas_restore'>SkCanvas::restore</a>
---
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