megalooper.cpp revision 11f2b444500d552031fcae0b381a0770600400fd
1/* 2 * Copyright 2013 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.h" 9#include "SkCanvas.h" 10#include "SkBlurMaskFilter.h" 11#include "SkLayerDrawLooper.h" 12#include "SkColorFilter.h" 13 14// This GM tests 3 different ways of drawing four shadows around a square: 15// just using 4 blurred rects 16// using 4 1-level draw loopers 17// using 1 4-level draw looper 18// They all produce exactly the same pixels 19class MegaLooperGM : public skiagm::GM { 20public: 21 // The types define "<# of loopers> x <# of stages per looper>" 22 enum Type { 23 k0x0_Type, // draw without loopers at all 24 k4x1_Type, // a looper for each shadow 25 k1x4_Type, // all four shadows in one looper 26 }; 27 28 MegaLooperGM(Type type) : fType(type) {} 29 30protected: 31 virtual SkString onShortName() { 32 switch (fType) { 33 case k0x0_Type: 34 return SkString("megalooper_0x0"); 35 break; 36 case k4x1_Type: 37 return SkString("megalooper_4x1"); 38 break; 39 case k1x4_Type: // fall through 40 default: 41 return SkString("megalooper_1x4"); 42 break; 43 } 44 } 45 46 virtual SkISize onISize() { 47 return SkISize::Make(kWidth, kHeight); 48 } 49 50 virtual void onDraw(SkCanvas* canvas) { 51 for (int y = 100; y < kHeight; y += 200) { 52 for (int x = 100; x < kWidth; x += 200) { 53 switch (fType) { 54 case k0x0_Type: 55 draw0x0(canvas, SkIntToScalar(x), SkIntToScalar(y)); 56 break; 57 case k4x1_Type: 58 draw4x1(canvas, SkIntToScalar(x), SkIntToScalar(y)); 59 break; 60 case k1x4_Type: // fall through 61 default: 62 draw1x4(canvas, SkIntToScalar(x), SkIntToScalar(y)); 63 break; 64 } 65 } 66 } 67 } 68 69private: 70 static const int kWidth = 800; 71 static const int kHeight = 800; 72 static const int kHalfOuterClipSize = 100; 73 static const int kHalfSquareSize = 50; 74 static const int kOffsetToOutsideClip = kHalfSquareSize + kHalfOuterClipSize + 1; 75 76 static const SkPoint gBlurOffsets[4]; 77 static const SkColor gColors[4]; 78 Type fType; 79 80 // Just draw a blurred rect at each of the four corners of a square (centered at x,y). 81 // Use two clips to define a rectori where we want pixels to appear. 82 void draw0x0(SkCanvas* canvas, SkScalar x, SkScalar y) { 83 SkRect innerClip = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize }; 84 innerClip.offset(x, y); 85 86 SkRect outerClip = { 87 -kHalfOuterClipSize-kHalfSquareSize, -kHalfOuterClipSize-kHalfSquareSize, 88 kHalfOuterClipSize+kHalfSquareSize, kHalfOuterClipSize+kHalfSquareSize 89 }; 90 outerClip.offset(x, y); 91 92 canvas->save(); 93 canvas->clipRect(outerClip, SkRegion::kIntersect_Op); 94 canvas->clipRect(innerClip, SkRegion::kDifference_Op); 95 96 SkPaint paint; 97 paint.setAntiAlias(true); 98 paint.setMaskFilter(createBlur())->unref(); 99 100 for (int i = 0; i < 4; ++i) { 101 paint.setColor(gColors[i]); 102 103 SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize }; 104 rect.offset(gBlurOffsets[i]); 105 rect.offset(x, y); 106 canvas->drawRect(rect, paint); 107 } 108 109 canvas->restore(); 110 } 111 112 SkMaskFilter* createBlur() { 113 static const SkScalar kBlurRadius = 25.0f; 114 115 return SkBlurMaskFilter::Create(kBlurRadius, 116 SkBlurMaskFilter::kNormal_BlurStyle, 117 SkBlurMaskFilter::kHighQuality_BlurFlag); 118 } 119 120 // This draws 4 blurred shadows around a single square (centered at x, y). 121 // Each blur is offset +/- half the square's side in x & y from the original 122 // (so each blurred rect is centered at one of the corners of the original). 123 // For each blur a large outer clip is centered around the blurred rect 124 // while a difference clip stays at the location of the original rect. 125 // Each blurred rect is drawn with a draw looper where the original (non- 126 // blurred rect) is offset to reside outside of the large outer clip (so 127 // it never appears) but the offset in the draw looper is used to translate 128 // the blurred version back into the clip. 129 void draw4x1(SkCanvas* canvas, SkScalar x, SkScalar y) { 130 131 for (int i = 0; i < 4; ++i) { 132 SkPaint loopPaint; 133 134 loopPaint.setLooper(create1Looper(-kOffsetToOutsideClip, 0, gColors[i])); 135 loopPaint.setAntiAlias(true); 136 137 SkRect outerClip = { 138 -kHalfOuterClipSize, -kHalfOuterClipSize, 139 kHalfOuterClipSize, kHalfOuterClipSize 140 }; 141 outerClip.offset(x, y); 142 // center it on the blurred rect 143 outerClip.offset(gBlurOffsets[i]); 144 145 SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize }; 146 rect.offset(x, y); 147 148 canvas->save(); 149 canvas->clipRect(outerClip, SkRegion::kIntersect_Op); 150 canvas->clipRect(rect, SkRegion::kDifference_Op); 151 152 // move the rect to where we want the blur to appear 153 rect.offset(gBlurOffsets[i]); 154 // then move it outside the clip (the blur stage of the draw 155 // looper will undo this translation) 156 rect.offset(SkIntToScalar(kOffsetToOutsideClip), 0); 157 158 canvas->drawRect(rect, loopPaint); 159 canvas->restore(); 160 } 161 } 162 163 // Create a 1-tier drawlooper 164 SkLayerDrawLooper* create1Looper(SkScalar xOff, SkScalar yOff, SkColor color) { 165 SkLayerDrawLooper* looper = new SkLayerDrawLooper; 166 SkLayerDrawLooper::LayerInfo info; 167 168 info.fFlagsMask = 0; 169 info.fPaintBits = SkLayerDrawLooper::kColorFilter_Bit | 170 SkLayerDrawLooper::kMaskFilter_Bit; 171 info.fColorMode = SkXfermode::kSrc_Mode; 172 info.fOffset.set(xOff, yOff); 173 info.fPostTranslate = false; 174 175 SkPaint* paint = looper->addLayer(info); 176 177 paint->setMaskFilter(this->createBlur())->unref(); 178 179 SkColorFilter* cf = SkColorFilter::CreateModeFilter(color, SkXfermode::kSrcIn_Mode); 180 paint->setColorFilter(cf)->unref(); 181 182 return looper; 183 } 184 185 void draw1x4(SkCanvas* canvas, SkScalar x, SkScalar y) { 186 SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize }; 187 rect.offset(x, y); 188 189 SkRect outerClip = { 190 -kHalfOuterClipSize-kHalfSquareSize, -kHalfOuterClipSize-kHalfSquareSize, 191 kHalfOuterClipSize+kHalfSquareSize, kHalfOuterClipSize+kHalfSquareSize 192 }; 193 outerClip.offset(x, y); 194 195 SkPaint paint; 196 paint.setAntiAlias(true); 197 paint.setLooper(create4Looper(-kOffsetToOutsideClip-kHalfSquareSize, 0)); 198 199 canvas->save(); 200 canvas->clipRect(outerClip, SkRegion::kIntersect_Op); 201 canvas->clipRect(rect, SkRegion::kDifference_Op); 202 203 rect.offset(SkIntToScalar(kOffsetToOutsideClip+kHalfSquareSize), 0); 204 canvas->drawRect(rect, paint); 205 canvas->restore(); 206 } 207 208 // Create a 4-tier draw looper 209 SkLayerDrawLooper* create4Looper(SkScalar xOff, SkScalar yOff) { 210 SkLayerDrawLooper* looper = new SkLayerDrawLooper; 211 SkLayerDrawLooper::LayerInfo info; 212 213 info.fFlagsMask = 0; 214 info.fPaintBits = SkLayerDrawLooper::kColorFilter_Bit | 215 SkLayerDrawLooper::kMaskFilter_Bit; 216 info.fColorMode = SkXfermode::kSrc_Mode; 217 info.fPostTranslate = false; 218 219 SkPaint* paint; 220 221 for (int i = 3; i >= 0; --i) { 222 info.fOffset.set(xOff+gBlurOffsets[i].fX, yOff+gBlurOffsets[i].fY); 223 paint = looper->addLayer(info); 224 225 paint->setMaskFilter(this->createBlur())->unref(); 226 227 SkColorFilter* cf = SkColorFilter::CreateModeFilter(gColors[i], SkXfermode::kSrcIn_Mode); 228 paint->setColorFilter(cf)->unref(); 229 } 230 231 return looper; 232 } 233 234 typedef GM INHERITED; 235}; 236 237const SkPoint MegaLooperGM::gBlurOffsets[4] = { 238 { kHalfSquareSize, kHalfSquareSize }, 239 { -kHalfSquareSize, kHalfSquareSize }, 240 { kHalfSquareSize, -kHalfSquareSize }, 241 { -kHalfSquareSize, -kHalfSquareSize } 242}; 243 244const SkColor MegaLooperGM::gColors[4] = { 245 SK_ColorGREEN, SK_ColorYELLOW, SK_ColorBLUE, SK_ColorRED 246}; 247 248DEF_GM( return new MegaLooperGM(MegaLooperGM::k0x0_Type); ) 249DEF_GM( return new MegaLooperGM(MegaLooperGM::k4x1_Type); ) 250DEF_GM( return new MegaLooperGM(MegaLooperGM::k1x4_Type); ) 251