1 /*
2 * Copyright 2015 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 "gm/gm.h"
9 #include "include/core/SkBitmap.h"
10 #include "include/core/SkCanvas.h"
11 #include "include/core/SkColor.h"
12 #include "include/core/SkPaint.h"
13 #include "include/core/SkPoint.h"
14 #include "include/core/SkRect.h"
15 #include "include/core/SkRefCnt.h"
16 #include "include/core/SkScalar.h"
17 #include "include/core/SkShader.h"
18 #include "include/core/SkSurface.h"
19 #include "include/core/SkTileMode.h"
20 #include "include/core/SkTypes.h"
21 #include "include/effects/SkGradientShader.h"
22
make_transparency(SkCanvas * canvas,SkScalar width,SkScalar height)23 static void make_transparency(SkCanvas* canvas, SkScalar width, SkScalar height) {
24 SkPoint pts[2];
25 pts[0] = SkPoint::Make(0, 0);
26 pts[1] = SkPoint::Make(width, 0);
27 const SkColor kColors[] = {
28 SK_ColorBLACK,
29 SK_ColorGRAY,
30 SK_ColorWHITE,
31 SK_ColorRED,
32 SK_ColorYELLOW,
33 SK_ColorGREEN,
34 SK_ColorCYAN,
35 SK_ColorBLUE,
36 SK_ColorMAGENTA,
37 };
38 const SkScalar kRowHeight = height / SK_ARRAY_COUNT(kColors);
39 for (size_t i = 0; i < SK_ARRAY_COUNT(kColors); ++i) {
40 SkColor shaderColors[2];
41 shaderColors[0] = SK_AlphaTRANSPARENT;
42 shaderColors[1] = kColors[i];
43 SkPaint p;
44 p.setShader(SkGradientShader::MakeLinear(pts, shaderColors, nullptr, 2, SkTileMode::kClamp));
45 canvas->drawRect(SkRect::MakeXYWH(0, i * kRowHeight, width, kRowHeight), p);
46 }
47 }
48
49 // http://crrev.com/834303005
create_checkerboard_shader(SkColor c1,SkColor c2,int size)50 static sk_sp<SkShader> create_checkerboard_shader(SkColor c1, SkColor c2, int size) {
51 SkBitmap bm;
52 bm.allocN32Pixels(2 * size, 2 * size);
53 bm.eraseColor(c1);
54 bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
55 bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
56 return bm.makeShader(SkTileMode::kRepeat, SkTileMode::kRepeat);
57 }
58
59 // http://crrev.com/834303005
checkerboard(SkCanvas * canvas,SkColor c1,SkColor c2,int size)60 static void checkerboard(SkCanvas* canvas, SkColor c1, SkColor c2, int size) {
61 SkPaint paint;
62 paint.setShader(create_checkerboard_shader(c1, c2, size));
63 canvas->drawPaint(paint);
64 }
65
66 /**
67 * This GM verifies that a transparent bitmap drawn over a
68 * checkerboard pattern looks correct.
69 */
70 DEF_SIMPLE_GM(transparency_check, canvas, 1792, 1080) {
71 checkerboard(canvas, 0xFF999999, 0xFF666666, 8);
72 {
73 SkAutoCanvasRestore autoCanvasRestore(canvas, true);
74 auto surface(SkSurface::MakeRasterN32Premul(256, 9));
75 make_transparency(surface->getCanvas(), 256.0f, 9.0f);
76 canvas->scale(7.0f, 120.0f);
77 surface->draw(canvas, 0, 0, nullptr);
78 }
79 }
80