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 "SkGradientShader.h"
9 #include "SkSurface.h"
10 #include "gm.h"
11 #include "sk_tool_utils.h"
12
make_transparency(SkCanvas * canvas,SkScalar width,SkScalar height)13 static void make_transparency(SkCanvas* canvas, SkScalar width, SkScalar height) {
14 SkPoint pts[2];
15 pts[0] = SkPoint::Make(0, 0);
16 pts[1] = SkPoint::Make(width, 0);
17 const SkColor kColors[] = {
18 SK_ColorBLACK,
19 SK_ColorGRAY,
20 SK_ColorWHITE,
21 SK_ColorRED,
22 SK_ColorYELLOW,
23 SK_ColorGREEN,
24 SK_ColorCYAN,
25 SK_ColorBLUE,
26 SK_ColorMAGENTA,
27 };
28 const SkScalar kRowHeight = height / SK_ARRAY_COUNT(kColors);
29 for (size_t i = 0; i < SK_ARRAY_COUNT(kColors); ++i) {
30 SkColor shaderColors[2];
31 shaderColors[0] = SK_AlphaTRANSPARENT;
32 shaderColors[1] = kColors[i];
33 SkPaint p;
34 p.setShader(SkGradientShader::MakeLinear(pts, shaderColors, nullptr, 2,
35 SkShader::kClamp_TileMode));
36 canvas->drawRect(SkRect::MakeXYWH(0, i * kRowHeight, width, kRowHeight), p);
37 }
38 }
39
40 // http://crrev.com/834303005
create_checkerboard_shader(SkColor c1,SkColor c2,int size)41 static sk_sp<SkShader> create_checkerboard_shader(SkColor c1, SkColor c2, int size) {
42 SkBitmap bm;
43 bm.allocN32Pixels(2 * size, 2 * size);
44 bm.eraseColor(c1);
45 bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
46 bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
47 return SkShader::MakeBitmapShader(bm, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
48 }
49
50 // http://crrev.com/834303005
checkerboard(SkCanvas * canvas,SkColor c1,SkColor c2,int size)51 static void checkerboard(SkCanvas* canvas, SkColor c1, SkColor c2, int size) {
52 SkPaint paint;
53 paint.setShader(create_checkerboard_shader(c1, c2, size));
54 canvas->drawPaint(paint);
55 }
56
57 /**
58 * This GM verifies that a transparent bitmap drawn over a
59 * checkerboard pattern looks correct.
60 */
61 DEF_SIMPLE_GM(transparency_check, canvas, 1792, 1080) {
62 checkerboard(canvas, sk_tool_utils::color_to_565(0xFF999999),
63 sk_tool_utils::color_to_565(0xFF666666), 8);
64 {
65 SkAutoCanvasRestore autoCanvasRestore(canvas, true);
66 auto surface(SkSurface::MakeRasterN32Premul(256, 9));
67 make_transparency(surface->getCanvas(), 256.0f, 9.0f);
68 canvas->scale(7.0f, 120.0f);
69 surface->draw(canvas, 0, 0, nullptr);
70 }
71 }
72