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