samplecode/SampleLayerMask.cpp

   1 /*
   2  * Copyright 2011 Google Inc.
   3  *
   4  * Use of this source code is governed by a BSD-style license that can be
   5  * found in the LICENSE file.
   6  */
   7
   8 #include "SampleCode.h"
   9 #include "SkBitmap.h"
  10 #include "SkCanvas.h"
  11 #include "SkPaint.h"
  12 #include "SkPath.h"
  13 #include "SkView.h"
  14
  15 ///////////////////////////////////////////////////////////////////////////////
  16
  17 class LayerMaskView : public SampleView {
  18 public:
  19     LayerMaskView() {
  20         this->setBGColor(0xFFDDDDDD);
  21     }
  22
  23 protected:
  24     // overrides from SkEventSink
  25     virtual bool onQuery(SkEvent* evt) {
  26         if (SampleCode::TitleQ(*evt)) {
  27             SampleCode::TitleR(evt, "LayerMask");
  28             return true;
  29         }
  30         return this->INHERITED::onQuery(evt);
  31     }
  32
  33     void drawMask(SkCanvas* canvas, const SkRect& r) {
  34         SkPaint paint;
  35         paint.setAntiAlias(true);
  36
  37         if (true) {
  38             SkBitmap mask;
  39             int w = SkScalarRoundToInt(r.width());
  40             int h = SkScalarRoundToInt(r.height());
  41             mask.allocN32Pixels(w, h);
  42             mask.eraseColor(SK_ColorTRANSPARENT);
  43             SkCanvas c(mask);
  44             SkRect bounds = r;
  45             bounds.offset(-bounds.fLeft, -bounds.fTop);
  46             c.drawOval(bounds, paint);
  47
  48             paint.setBlendMode(SkBlendMode::kDstIn);
  49             canvas->drawBitmap(mask, r.fLeft, r.fTop, &paint);
  50         } else {
  51             SkPath p;
  52             p.addOval(r);
  53             p.setFillType(SkPath::kInverseWinding_FillType);
  54             paint.setBlendMode(SkBlendMode::kDstOut);
  55             canvas->drawPath(p, paint);
  56         }
  57     }
  58
  59     virtual void onDrawContent(SkCanvas* canvas) {
  60         SkRect  r;
  61         r.set(SkIntToScalar(20), SkIntToScalar(20), SkIntToScalar(120), SkIntToScalar(120));
  62         canvas->saveLayer(&r, nullptr);
  63         canvas->drawColor(SK_ColorRED);
  64         drawMask(canvas, r);
  65         canvas->restore();
  66     }
  67
  68 private:
  69     typedef SampleView INHERITED;
  70 };
  71
  72 ///////////////////////////////////////////////////////////////////////////////
  73
  74 static SkView* MyFactory() { return new LayerMaskView; }
  75 static SkViewRegister reg(MyFactory);