| #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. |
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| #Subtopic Constructor |
| #Populate |
| ## |
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| #Subtopic Member_Function |
| #Populate |
| ## |
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| #Method SkAutoCanvasRestore(SkCanvas* canvas, bool doSave) |
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| #Line # preserves Canvas save count ## |
| Preserves Canvas save count. Optionally saves Canvas_Clip and Canvas_Matrix. |
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| #Param canvas Canvas to guard ## |
| #Param doSave call SkCanvas::save() ## |
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| #Return utility to restore Canvas state on destructor ## |
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| #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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| ## |
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| #Method ~SkAutoCanvasRestore() |
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| #Line # restores Canvas to saved state ## |
| Restores Canvas to saved state. Destructor is called when container goes out of |
| scope. |
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| #NoExample |
| ## |
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| #SeeAlso SkCanvas::save SkCanvas::restore |
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| ## |
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| #Method void restore() |
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| #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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| ## |
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| #Class SkAutoCanvasRestore ## |
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| #Topic Automatic_Canvas_Restore ## |