skia2/docs/SkAutoCanvasRestore_Reference.bmh

#Topic Automatic_Canvas_Restore

#Subtopic Overview
    #Subtopic Subtopic
    #Populate
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#Class SkAutoCanvasRestore

Stack helper class calls SkCanvas::restoreToCount when SkAutoCanvasRestore
goes out of scope. Use this to guarantee that the canvas is restored to a known
state.

#Subtopic Constructor
#Populate
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#Subtopic Member_Function
#Populate
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#Method SkAutoCanvasRestore(SkCanvas* canvas, bool doSave)

#Line # preserves Canvas save count ##
Preserves Canvas save count. Optionally saves Canvas_Clip and Canvas_Matrix.

#Param canvas  Canvas to guard ##
#Param doSave  call SkCanvas::save() ##

#Return utility to restore Canvas state on destructor ##

#Example
#Height 128
    SkPaint p;
    p.setAntiAlias(true);
    p.setTextSize(64);
    for (SkScalar sx : { -1, 1 } ) {
        for (SkScalar sy : { -1, 1 } ) {
            SkAutoCanvasRestore autoRestore(canvas, true);
            SkMatrix m = SkMatrix::MakeAll(sx, 1, 96,    0, sy, 64,   0, 0, 1);
            canvas->concat(m);
            canvas->drawString("R", 0, 0, p);
        }
    }
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#SeeAlso SkCanvas::save SkCanvas::restore

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#Method ~SkAutoCanvasRestore()

#Line # restores Canvas to saved state ##
Restores Canvas to saved state. Destructor is called when container goes out of
scope.

#NoExample
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#SeeAlso SkCanvas::save SkCanvas::restore

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#Method void restore()
#In Member_Function
#Line # restores Canvas to saved state ##
Restores Canvas to saved state immediately. Subsequent calls and
~SkAutoCanvasRestore have no effect.

#Example
for (bool callRestore : { false, true } ) {
    for (bool saveCanvas : {false, true} ) {
        SkAutoCanvasRestore autoRestore(canvas, saveCanvas);
        if (!saveCanvas) {
            canvas->save();
        }
        SkDebugf("saveCanvas: %s  before restore: %d\n",
               saveCanvas ? "true" : "false", canvas->getSaveCount());
        if (callRestore) autoRestore.restore();
        SkDebugf("saveCanvas: %s  after restore: %d\n",
               saveCanvas ? "true" : "false", canvas->getSaveCount());
    }
}
SkDebugf("final count: %d\n", canvas->getSaveCount());
#StdOut
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
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#SeeAlso SkCanvas::save SkCanvas::restore

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#Class SkAutoCanvasRestore ##

#Topic Automatic_Canvas_Restore ##