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/*
* 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]))->unref();
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))->unref();
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); )