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      1 #Topic Automatic_Canvas_Restore
      2 
      3 #Class SkAutoCanvasRestore
      4 
      5 #Code
      6 #Populate
      7 ##
      8 
      9 Stack helper class calls SkCanvas::restoreToCount when SkAutoCanvasRestore
     10 goes out of scope. Use this to guarantee that the canvas is restored to a known
     11 state.
     12 
     13 #Method SkAutoCanvasRestore(SkCanvas* canvas, bool doSave)
     14 
     15 #Line # restores Canvas when out of scope ##
     16 #Populate
     17 
     18 #Example
     19 #Height 128
     20     SkPaint p;
     21     p.setAntiAlias(true);
     22     p.setTextSize(64);
     23     for (SkScalar sx : { -1, 1 } ) {
     24         for (SkScalar sy : { -1, 1 } ) {
     25             SkAutoCanvasRestore autoRestore(canvas, true);
     26             SkMatrix m = SkMatrix::MakeAll(sx, 1, 96,    0, sy, 64,   0, 0, 1);
     27             canvas->concat(m);
     28             canvas->drawString("R", 0, 0, p);
     29         }
     30     }
     31 ##
     32 
     33 #SeeAlso SkCanvas::save SkCanvas::restore
     34 
     35 ##
     36 
     37 #Method ~SkAutoCanvasRestore()
     38 
     39 #Line # restores Canvas to saved state ##
     40 #Populate
     41 
     42 #NoExample
     43 ##
     44 
     45 #SeeAlso SkCanvas::save SkCanvas::restore
     46 
     47 ##
     48 
     49 #Method void restore()
     50 #In Member_Function
     51 #Line # restores Canvas to saved state ##
     52 #Populate
     53 
     54 #Example
     55 for (bool callRestore : { false, true } ) {
     56     for (bool saveCanvas : {false, true} ) {
     57         SkAutoCanvasRestore autoRestore(canvas, saveCanvas);
     58         if (!saveCanvas) {
     59             canvas->save();
     60         }
     61         SkDebugf("saveCanvas: %s  before restore: %d\n",
     62                saveCanvas ? "true" : "false", canvas->getSaveCount());
     63         if (callRestore) autoRestore.restore();
     64         SkDebugf("saveCanvas: %s  after restore: %d\n",
     65                saveCanvas ? "true" : "false", canvas->getSaveCount());
     66     }
     67 }
     68 SkDebugf("final count: %d\n", canvas->getSaveCount());
     69 #StdOut
     70 saveCanvas: false  before restore: 2
     71 saveCanvas: false  after restore: 2
     72 saveCanvas: true  before restore: 2
     73 saveCanvas: true  after restore: 2
     74 saveCanvas: false  before restore: 2
     75 saveCanvas: false  after restore: 1
     76 saveCanvas: true  before restore: 2
     77 saveCanvas: true  after restore: 1
     78 final count: 1
     79 ##
     80 ##
     81 
     82 #SeeAlso SkCanvas::save SkCanvas::restore
     83 
     84 ##
     85 
     86 #Class SkAutoCanvasRestore ##
     87 
     88 #Topic Automatic_Canvas_Restore ##
     89