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);
76