Added megalooper GM
https://codereview.chromium.org/16004011/
git-svn-id: http://skia.googlecode.com/svn/trunk@9409 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/megalooper.cpp b/gm/megalooper.cpp
new file mode 100644
index 0000000..8f5932c
--- /dev/null
+++ b/gm/megalooper.cpp
@@ -0,0 +1,250 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkCanvas.h"
+#include "SkBlurMaskFilter.h"
+#include "SkLayerDrawLooper.h"
+#include "SkColorFilter.h"
+
+// This GM tests 3 different ways of drawing four shadows around a square:
+// just using 4 blurred rects
+// using 4 1-level draw loopers
+// using 1 4-level draw looper
+// They all produce exactly the same pixels
+class MegaLooperGM : public skiagm::GM {
+public:
+ // The types define "<# of loopers> x <# of stages per looper>"
+ enum Type {
+ k0x0_Type, // draw without loopers at all
+ k4x1_Type, // a looper for each shadow
+ k1x4_Type, // all four shadows in one looper
+ };
+
+ MegaLooperGM(Type type) : fType(type) {}
+
+protected:
+ virtual SkString onShortName() {
+ switch (fType) {
+ case k0x0_Type:
+ return SkString("megalooper_0x0");
+ break;
+ case k4x1_Type:
+ return SkString("megalooper_4x1");
+ break;
+ case k1x4_Type: // fall through
+ default:
+ return SkString("megalooper_1x4");
+ break;
+ }
+ }
+
+ virtual SkISize onISize() {
+ return SkISize::Make(kWidth, kHeight);
+ }
+
+ virtual void onDraw(SkCanvas* canvas) {
+ for (int y = 100; y < kHeight; y += 200) {
+ for (int x = 100; x < kWidth; x += 200) {
+ switch (fType) {
+ case k0x0_Type:
+ draw0x0(canvas, SkIntToScalar(x), SkIntToScalar(y));
+ break;
+ case k4x1_Type:
+ draw4x1(canvas, SkIntToScalar(x), SkIntToScalar(y));
+ break;
+ case k1x4_Type: // fall through
+ default:
+ draw1x4(canvas, SkIntToScalar(x), SkIntToScalar(y));
+ break;
+ }
+ }
+ }
+ }
+
+private:
+ static const int kWidth = 800;
+ static const int kHeight = 800;
+ static const int kHalfOuterClipSize = 100;
+ static const int kHalfSquareSize = 50;
+ static const int kOffsetToOutsideClip = kHalfSquareSize + kHalfOuterClipSize + 1;
+
+ static const SkPoint gBlurOffsets[4];
+ static const SkColor gColors[4];
+ Type fType;
+
+ // Just draw a blurred rect at each of the four corners of a square (centered at x,y).
+ // Use two clips to define a rectori where we want pixels to appear.
+ void draw0x0(SkCanvas* canvas, SkScalar x, SkScalar y) {
+ SkRect innerClip = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize };
+ innerClip.offset(x, y);
+
+ SkRect outerClip = {
+ -kHalfOuterClipSize-kHalfSquareSize, -kHalfOuterClipSize-kHalfSquareSize,
+ kHalfOuterClipSize+kHalfSquareSize, kHalfOuterClipSize+kHalfSquareSize
+ };
+ outerClip.offset(x, y);
+
+ canvas->save();
+ canvas->clipRect(outerClip, SkRegion::kIntersect_Op);
+ canvas->clipRect(innerClip, SkRegion::kDifference_Op);
+
+ SkPaint paint;
+ paint.setAntiAlias(true);
+ paint.setMaskFilter(createBlur())->unref();
+
+ for (int i = 0; i < 4; ++i) {
+ paint.setColor(gColors[i]);
+
+ SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize };
+ rect.offset(gBlurOffsets[i]);
+ rect.offset(x, y);
+ canvas->drawRect(rect, paint);
+ }
+
+ canvas->restore();
+ }
+
+ SkMaskFilter* createBlur() {
+ static const SkScalar kBlurRadius = 25.0f;
+
+ return SkBlurMaskFilter::Create(kBlurRadius,
+ SkBlurMaskFilter::kNormal_BlurStyle,
+ SkBlurMaskFilter::kHighQuality_BlurFlag);
+ }
+
+ // This draws 4 blurred shadows around a single square (centered at x, y).
+ // Each blur is offset +/- half the square's side in x & y from the original
+ // (so each blurred rect is centered at one of the corners of the original).
+ // For each blur a large outer clip is centered around the blurred rect
+ // while a difference clip stays at the location of the original rect.
+ // Each blurred rect is drawn with a draw looper where the original (non-
+ // blurred rect) is offset to reside outside of the large outer clip (so
+ // it never appears) but the offset in the draw looper is used to translate
+ // the blurred version back into the clip.
+ void draw4x1(SkCanvas* canvas, SkScalar x, SkScalar y) {
+
+ for (int i = 0; i < 4; ++i) {
+ SkPaint loopPaint;
+
+ loopPaint.setLooper(create1Looper(-kOffsetToOutsideClip, 0, gColors[i]));
+ loopPaint.setAntiAlias(true);
+
+ SkRect outerClip = {
+ -kHalfOuterClipSize, -kHalfOuterClipSize,
+ kHalfOuterClipSize, kHalfOuterClipSize
+ };
+ outerClip.offset(x, y);
+ // center it on the blurred rect
+ outerClip.offset(gBlurOffsets[i]);
+
+ SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize };
+ rect.offset(x, y);
+
+ canvas->save();
+ canvas->clipRect(outerClip, SkRegion::kIntersect_Op);
+ canvas->clipRect(rect, SkRegion::kDifference_Op);
+
+ // move the rect to where we want the blur to appear
+ rect.offset(gBlurOffsets[i]);
+ // then move it outside the clip (the blur stage of the draw
+ // looper will undo this translation)
+ rect.offset(SkIntToScalar(kOffsetToOutsideClip), 0);
+
+ canvas->drawRect(rect, loopPaint);
+ canvas->restore();
+ }
+ }
+
+ // Create a 1-tier drawlooper
+ SkLayerDrawLooper* create1Looper(SkScalar xOff, SkScalar yOff, SkColor color) {
+ SkLayerDrawLooper* looper = new SkLayerDrawLooper;
+ SkLayerDrawLooper::LayerInfo info;
+
+ info.fFlagsMask = 0;
+ info.fPaintBits = SkLayerDrawLooper::kColorFilter_Bit |
+ SkLayerDrawLooper::kMaskFilter_Bit;
+ info.fColorMode = SkXfermode::kSrc_Mode;
+ info.fOffset.set(xOff, yOff);
+ info.fPostTranslate = false;
+
+ SkPaint* paint = looper->addLayer(info);
+
+ paint->setMaskFilter(this->createBlur())->unref();
+
+ SkColorFilter* cf = SkColorFilter::CreateModeFilter(color, SkXfermode::kSrcIn_Mode);
+ paint->setColorFilter(cf)->unref();
+
+ return looper;
+ }
+
+ void draw1x4(SkCanvas* canvas, SkScalar x, SkScalar y) {
+ SkRect rect = { -kHalfSquareSize, -kHalfSquareSize, kHalfSquareSize, kHalfSquareSize };
+ rect.offset(x, y);
+
+ SkRect outerClip = {
+ -kHalfOuterClipSize-kHalfSquareSize, -kHalfOuterClipSize-kHalfSquareSize,
+ kHalfOuterClipSize+kHalfSquareSize, kHalfOuterClipSize+kHalfSquareSize
+ };
+ outerClip.offset(x, y);
+
+ SkPaint paint;
+ paint.setAntiAlias(true);
+ paint.setLooper(create4Looper(-kOffsetToOutsideClip-kHalfSquareSize, 0));
+
+ canvas->save();
+ canvas->clipRect(outerClip, SkRegion::kIntersect_Op);
+ canvas->clipRect(rect, SkRegion::kDifference_Op);
+
+ rect.offset(SkIntToScalar(kOffsetToOutsideClip+kHalfSquareSize), 0);
+ canvas->drawRect(rect, paint);
+ canvas->restore();
+ }
+
+ // Create a 4-tier draw looper
+ SkLayerDrawLooper* create4Looper(SkScalar xOff, SkScalar yOff) {
+ SkLayerDrawLooper* looper = new SkLayerDrawLooper;
+ SkLayerDrawLooper::LayerInfo info;
+
+ info.fFlagsMask = 0;
+ info.fPaintBits = SkLayerDrawLooper::kColorFilter_Bit |
+ SkLayerDrawLooper::kMaskFilter_Bit;
+ info.fColorMode = SkXfermode::kSrc_Mode;
+ info.fPostTranslate = false;
+
+ SkPaint* paint;
+
+ for (int i = 3; i >= 0; --i) {
+ info.fOffset.set(xOff+gBlurOffsets[i].fX, yOff+gBlurOffsets[i].fY);
+ paint = looper->addLayer(info);
+
+ paint->setMaskFilter(this->createBlur())->unref();
+
+ SkColorFilter* cf = SkColorFilter::CreateModeFilter(gColors[i], SkXfermode::kSrcIn_Mode);
+ paint->setColorFilter(cf)->unref();
+ }
+
+ return looper;
+ }
+
+ typedef GM INHERITED;
+};
+
+const SkPoint MegaLooperGM::gBlurOffsets[4] = {
+ { kHalfSquareSize, kHalfSquareSize },
+ { -kHalfSquareSize, kHalfSquareSize },
+ { kHalfSquareSize, -kHalfSquareSize },
+ { -kHalfSquareSize, -kHalfSquareSize }
+};
+
+const SkColor MegaLooperGM::gColors[4] = {
+ SK_ColorGREEN, SK_ColorYELLOW, SK_ColorBLUE, SK_ColorRED
+};
+
+DEF_GM( return new MegaLooperGM(MegaLooperGM::k0x0_Type); )
+DEF_GM( return new MegaLooperGM(MegaLooperGM::k4x1_Type); )
+DEF_GM( return new MegaLooperGM(MegaLooperGM::k1x4_Type); )