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Add AlphaThreshold filter.

Browse Source 
This is based on the Bitmap Alpha Threshold filter, and will be used by Chromium
to implement the window shape API.

R=bsalomon@chromium.org, wez@chromium.org, bsalomon@google.com, reed@google.com

Author: zork@chromium.org

Review URL: https://codereview.chromium.org/115633002

git-svn-id: http://skia.googlecode.com/svn/trunk@12935 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
commit-bot@chromium.org 2014-01-06 23:41:14 +00:00
parent f6c8aeb174
commit 40eb3c1000
7 changed files with 481 additions and 0 deletions
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82
gm/imagealphathreshold.cpp Normal file
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@ -0,0 +1,82 @@
/*
* 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 "SkAlphaThresholdFilter.h"
#include "SkRandom.h"
#define WIDTH 500
#define HEIGHT 500
namespace skiagm {
class ImageAlphaThresholdGM : public GM {
public:
ImageAlphaThresholdGM() {
this->setBGColor(0xFFFFFFFF);
}
protected:
virtual uint32_t onGetFlags() const SK_OVERRIDE {
return this->INHERITED::onGetFlags() | GM::kSkipTiled_Flag;
}
virtual SkString onShortName() SK_OVERRIDE {
return SkString("imagealphathreshold");
}
virtual SkISize onISize() SK_OVERRIDE {
return make_isize(WIDTH, HEIGHT);
}
virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
SkIRect rects[2];
rects[0] = SkIRect::MakeXYWH(0, 150, WIDTH, HEIGHT - 300);
rects[1] = SkIRect::MakeXYWH(150, 0, WIDTH - 300, HEIGHT);
SkRegion region;
region.setRects(rects, 2);
SkMatrix matrix;
matrix.reset();
matrix.setTranslate(WIDTH * .1f, HEIGHT * .1f);
matrix.postScale(.8, .8);
canvas->concat(matrix);
SkPaint paint;
paint.setImageFilter(
SkAlphaThresholdFilter::Create(region, 0.2f, 0.7f))->unref();
canvas->saveLayer(NULL, &paint);
paint.setAntiAlias(true);
SkPaint rect_paint;
rect_paint.setColor(0xFF0000FF);
canvas->drawRect(SkRect::MakeXYWH(0, 0, WIDTH / 2, HEIGHT / 2),
rect_paint);
rect_paint.setColor(0xBFFF0000);
canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, 0, WIDTH / 2, HEIGHT / 2),
rect_paint);
rect_paint.setColor(0x3F00FF00);
canvas->drawRect(SkRect::MakeXYWH(0, HEIGHT / 2, WIDTH / 2, HEIGHT / 2),
rect_paint);
rect_paint.setColor(0x00000000);
canvas->drawRect(SkRect::MakeXYWH(WIDTH / 2, HEIGHT / 2, WIDTH / 2, HEIGHT / 2),
rect_paint);
canvas->restore();
}
private:
typedef GM INHERITED;
};
//////////////////////////////////////////////////////////////////////////////
static GM* MyFactory(void*) { return new ImageAlphaThresholdGM; }
static GMRegistry reg(MyFactory);
}

2
gyp/effects.gypi
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@ -9,6 +9,7 @@
'sources': [
'<(skia_src_path)/effects/Sk1DPathEffect.cpp',
'<(skia_src_path)/effects/Sk2DPathEffect.cpp',
'<(skia_src_path)/effects/SkAlphaThresholdFilter.cpp',
'<(skia_src_path)/effects/SkArithmeticMode.cpp',
'<(skia_src_path)/effects/SkAvoidXfermode.cpp',
'<(skia_src_path)/effects/SkBicubicImageFilter.cpp',
@ -80,6 +81,7 @@
'<(skia_include_path)/effects/Sk1DPathEffect.h',
'<(skia_include_path)/effects/Sk2DPathEffect.h',
'<(skia_include_path)/effects/SkXfermodeImageFilter.h',
'<(skia_include_path)/effects/SkAlphaThresholdFilter.h',
'<(skia_include_path)/effects/SkArithmeticMode.h',
'<(skia_include_path)/effects/SkAvoidXfermode.h',
'<(skia_include_path)/effects/SkBitmapSource.h',

1
gyp/gmslides.gypi
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@ -73,6 +73,7 @@
'../gm/hairlines.cpp',
'../gm/hairmodes.cpp',
'../gm/hittestpath.cpp',
'../gm/imagealphathreshold.cpp',
'../gm/imageblur.cpp',
'../gm/imagemagnifier.cpp',
'../gm/inversepaths.cpp',

1
gyp/public_headers.gypi
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@ -72,6 +72,7 @@
'effects/SkMorphologyImageFilter.h',
'effects/Sk2DPathEffect.h',
'effects/SkXfermodeImageFilter.h',
'effects/SkAlphaThresholdFilter.h',
'effects/SkArithmeticMode.h',
'effects/SkMergeImageFilter.h',
'effects/SkPerlinNoiseShader.h',

26
include/effects/SkAlphaThresholdFilter.h Normal file
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@ -0,0 +1,26 @@
/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkAlphaThresholdFilter_DEFINED
#define SkAlphaThresholdFilter_DEFINED
#include "SkRegion.h"
#include "SkImageFilter.h"
class SK_API SkAlphaThresholdFilter {
public:
/**
* Creates an image filter that samples a region. If the sample is inside the
* region the alpha of the image is boosted up to a threshold value. If it is
* outside the region then the alpha is decreased to the threshold value.
* The 0,0 point of the region corresponds to the upper left corner of the
* source image.
*/
static SkImageFilter* Create(const SkRegion& region, SkScalar innerThreshold, SkScalar outerThreshold);
};
#endif

367
src/effects/SkAlphaThresholdFilter.cpp Normal file
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@ -0,0 +1,367 @@
/*
* 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 "SkAlphaThresholdFilter.h"
#include "SkBitmap.h"
#include "SkFlattenableBuffers.h"
#include "SkRegion.h"
class SK_API SkAlphaThresholdFilterImpl : public SkImageFilter {
public:
SkAlphaThresholdFilterImpl(const SkRegion& region, SkScalar innerThreshold, SkScalar outerThreshold);
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkAlphaThresholdFilterImpl)
protected:
explicit SkAlphaThresholdFilterImpl(SkFlattenableReadBuffer& buffer);
virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
#if SK_SUPPORT_GPU
virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture,
const SkMatrix& matrix, const SkIRect& bounds) const SK_OVERRIDE;
#endif
private:
SkRegion fRegion;
SkScalar fInnerThreshold;
SkScalar fOuterThreshold;
typedef SkImageFilter INHERITED;
};
SkImageFilter* SkAlphaThresholdFilter::Create(const SkRegion& region,
SkScalar innerThreshold,
SkScalar outerThreshold) {
return SkNEW_ARGS(SkAlphaThresholdFilterImpl, (region, innerThreshold, outerThreshold));
}
#if SK_SUPPORT_GPU
#include "GrContext.h"
#include "GrCoordTransform.h"
#include "GrEffect.h"
#include "gl/GrGLEffect.h"
#include "GrTBackendEffectFactory.h"
#include "GrTextureAccess.h"
#include "SkGr.h"
class GrGLAlphaThresholdEffect;
class AlphaThresholdEffect : public GrEffect {
public:
static GrEffectRef* Create(GrTexture* texture,
GrTexture* maskTexture,
float innerThreshold,
float outerThreshold) {
AutoEffectUnref effect(SkNEW_ARGS(AlphaThresholdEffect, (texture,
maskTexture,
innerThreshold,
outerThreshold)));
return CreateEffectRef(effect);
}
virtual ~AlphaThresholdEffect() {};
static const char* Name() { return "Alpha Threshold"; }
virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
float innerThreshold() const { return fInnerThreshold; }
float outerThreshold() const { return fOuterThreshold; }
typedef GrGLAlphaThresholdEffect GLEffect;
private:
AlphaThresholdEffect(GrTexture* texture,
GrTexture* maskTexture,
float innerThreshold,
float outerThreshold)
: fInnerThreshold(innerThreshold)
, fOuterThreshold(outerThreshold)
, fImageCoordTransform(kLocal_GrCoordSet, MakeDivByTextureWHMatrix(texture), texture)
, fImageTextureAccess(texture)
, fMaskCoordTransform(kLocal_GrCoordSet, MakeDivByTextureWHMatrix(maskTexture), maskTexture)
, fMaskTextureAccess(maskTexture) {
this->addCoordTransform(&fImageCoordTransform);
this->addTextureAccess(&fImageTextureAccess);
this->addCoordTransform(&fMaskCoordTransform);
this->addTextureAccess(&fMaskTextureAccess);
}
virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
GR_DECLARE_EFFECT_TEST;
float fInnerThreshold;
float fOuterThreshold;
GrCoordTransform fImageCoordTransform;
GrTextureAccess fImageTextureAccess;
GrCoordTransform fMaskCoordTransform;
GrTextureAccess fMaskTextureAccess;
typedef GrEffect INHERITED;
};
class GrGLAlphaThresholdEffect : public GrGLEffect {
public:
GrGLAlphaThresholdEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
virtual void emitCode(GrGLShaderBuilder*,
const GrDrawEffect&,
EffectKey,
const char* outputColor,
const char* inputColor,
const TransformedCoordsArray&,
const TextureSamplerArray&) SK_OVERRIDE;
virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
private:
GrGLUniformManager::UniformHandle fInnerThresholdVar;
GrGLUniformManager::UniformHandle fOuterThresholdVar;
typedef GrGLEffect INHERITED;
};
GrGLAlphaThresholdEffect::GrGLAlphaThresholdEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
: INHERITED(factory) {
}
void GrGLAlphaThresholdEffect::emitCode(GrGLShaderBuilder* builder,
const GrDrawEffect&,
EffectKey key,
const char* outputColor,
const char* inputColor,
const TransformedCoordsArray& coords,
const TextureSamplerArray& samplers) {
SkString coords2D = builder->ensureFSCoords2D(coords, 0);
SkString maskCoords2D = builder->ensureFSCoords2D(coords, 1);
fInnerThresholdVar = builder->addUniform(
GrGLShaderBuilder::kFragment_Visibility,
kFloat_GrSLType, "inner_threshold");
fOuterThresholdVar = builder->addUniform(
GrGLShaderBuilder::kFragment_Visibility,
kFloat_GrSLType, "outer_threshold");
builder->fsCodeAppendf("\t\tvec2 coord = %s;\n", coords2D.c_str());
builder->fsCodeAppendf("\t\tvec2 mask_coord = %s;\n", maskCoords2D.c_str());
builder->fsCodeAppend("\t\tvec4 input_color = ");
builder->fsAppendTextureLookup(samplers[0], "coord");
builder->fsCodeAppend(";\n");
builder->fsCodeAppend("\t\tvec4 mask_color = ");
builder->fsAppendTextureLookup(samplers[1], "mask_coord");
builder->fsCodeAppend(";\n");
builder->fsCodeAppendf("\t\tfloat inner_thresh = %s;\n",
builder->getUniformCStr(fInnerThresholdVar));
builder->fsCodeAppendf("\t\tfloat outer_thresh = %s;\n",
builder->getUniformCStr(fOuterThresholdVar));
builder->fsCodeAppend("\t\tfloat mask = mask_color.a;\n");
builder->fsCodeAppend("vec4 color = input_color;\n");
builder->fsCodeAppend("\t\tif (mask < 0.5) {\n"
"\t\t\tif (color.a > outer_thresh) {\n"
"\t\t\t\tfloat scale = outer_thresh / color.a;\n"
"\t\t\t\tcolor.rgb *= scale;\n"
"\t\t\t\tcolor.a = outer_thresh;\n"
"\t\t\t}\n"
"\t\t} else if (color.a < inner_thresh) {\n"
"\t\t\tfloat scale = inner_thresh / max(0.001, color.a);\n"
"\t\t\tcolor.rgb *= scale;\n"
"\t\t\tcolor.a = inner_thresh;\n"
"\t\t}\n");
builder->fsCodeAppendf("%s = %s;\n", outputColor,
(GrGLSLExpr4(inputColor) * GrGLSLExpr4("color")).c_str());
}
void GrGLAlphaThresholdEffect::setData(const GrGLUniformManager& uman,
const GrDrawEffect& drawEffect) {
const AlphaThresholdEffect& alpha_threshold =
drawEffect.castEffect<AlphaThresholdEffect>();
uman.set1f(fInnerThresholdVar, alpha_threshold.innerThreshold());
uman.set1f(fOuterThresholdVar, alpha_threshold.outerThreshold());
}
/////////////////////////////////////////////////////////////////////
GR_DEFINE_EFFECT_TEST(AlphaThresholdEffect);
GrEffectRef* AlphaThresholdEffect::TestCreate(SkRandom* random,
GrContext* context,
const GrDrawTargetCaps&,
GrTexture** textures) {
GrTexture* bmpTex = textures[GrEffectUnitTest::kSkiaPMTextureIdx];
GrTexture* maskTex = textures[GrEffectUnitTest::kAlphaTextureIdx];
float inner_thresh = random->nextUScalar1();
float outer_thresh = random->nextUScalar1();
return AlphaThresholdEffect::Create(bmpTex, maskTex, inner_thresh, outer_thresh);
}
///////////////////////////////////////////////////////////////////////////////
const GrBackendEffectFactory& AlphaThresholdEffect::getFactory() const {
return GrTBackendEffectFactory<AlphaThresholdEffect>::getInstance();
}
bool AlphaThresholdEffect::onIsEqual(const GrEffect& sBase) const {
const AlphaThresholdEffect& s = CastEffect<AlphaThresholdEffect>(sBase);
return (this->texture(0) == s.texture(0) &&
this->fInnerThreshold == s.fInnerThreshold &&
this->fOuterThreshold == s.fOuterThreshold);
}
void AlphaThresholdEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
if ((*validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(*color) &&
GrPixelConfigIsOpaque(this->texture(0)->config())) {
*validFlags = kA_GrColorComponentFlag;
} else {
*validFlags = 0;
}
}
#endif
SkAlphaThresholdFilterImpl::SkAlphaThresholdFilterImpl(SkFlattenableReadBuffer& buffer)
: INHERITED(1, buffer) {
fInnerThreshold = buffer.readScalar();
fOuterThreshold = buffer.readScalar();
buffer.readRegion(&fRegion);
}
SkAlphaThresholdFilterImpl::SkAlphaThresholdFilterImpl(const SkRegion& region,
SkScalar innerThreshold,
SkScalar outerThreshold)
: INHERITED(0)
, fRegion(region)
, fInnerThreshold(innerThreshold)
, fOuterThreshold(outerThreshold) {
}
#if SK_SUPPORT_GPU
bool SkAlphaThresholdFilterImpl::asNewEffect(GrEffectRef** effect, GrTexture* texture,
const SkMatrix& in_matrix, const SkIRect&) const {
if (effect) {
GrContext* context = texture->getContext();
GrTextureDesc maskDesc;
if (context->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
maskDesc.fConfig = kAlpha_8_GrPixelConfig;
} else {
maskDesc.fConfig = kRGBA_8888_GrPixelConfig;
}
maskDesc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
// Add one pixel of border to ensure that clamp mode will be all zeros
// the outside.
maskDesc.fWidth = texture->width();
maskDesc.fHeight = texture->height();
GrAutoScratchTexture ast(context, maskDesc, GrContext::kApprox_ScratchTexMatch);
GrTexture* maskTexture = ast.texture();
if (NULL == maskTexture) {
return false;
}
{
GrContext::AutoRenderTarget art(context, ast.texture()->asRenderTarget());
GrPaint grPaint;
grPaint.setBlendFunc(kOne_GrBlendCoeff, kZero_GrBlendCoeff);
SkRegion::Iterator iter(fRegion);
context->clear(NULL, 0x0, true);
SkMatrix old_matrix = context->getMatrix();
context->setMatrix(in_matrix);
while (!iter.done()) {
SkRect rect = SkRect::Make(iter.rect());
context->drawRect(grPaint, rect);
iter.next();
}
context->setMatrix(old_matrix);
}
*effect = AlphaThresholdEffect::Create(texture,
maskTexture,
fInnerThreshold,
fOuterThreshold);
}
return true;
}
#endif
void SkAlphaThresholdFilterImpl::flatten(SkFlattenableWriteBuffer& buffer) const {
this->INHERITED::flatten(buffer);
buffer.writeScalar(fInnerThreshold);
buffer.writeScalar(fOuterThreshold);
buffer.writeRegion(fRegion);
}
bool SkAlphaThresholdFilterImpl::onFilterImage(Proxy*, const SkBitmap& src,
const SkMatrix& matrix, SkBitmap* dst,
SkIPoint* offset) {
SkASSERT(src.config() == SkBitmap::kARGB_8888_Config);
if (src.config() != SkBitmap::kARGB_8888_Config) {
return false;
}
SkMatrix localInverse;
if (!matrix.invert(&localInverse)) {
return NULL;
}
SkAutoLockPixels alp(src);
SkASSERT(src.getPixels());
if (!src.getPixels() || src.width() <= 0 || src.height() <= 0) {
return false;
}
dst->setConfig(src.config(), src.width(), src.height());
dst->allocPixels();
if (!dst->getPixels()) {
return false;
}
U8CPU innerThreshold = fInnerThreshold * 0xFF;
U8CPU outerThreshold = fOuterThreshold * 0xFF;
SkColor* sptr = src.getAddr32(0, 0);
SkColor* dptr = dst->getAddr32(0, 0);
int width = src.width(), height = src.height();
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
const SkColor& source = sptr[y * width + x];
SkColor output_color(source);
SkPoint position;
localInverse.mapXY(x, y, &position);
if (fRegion.contains(position.x(), position.y())) {
if (SkColorGetA(source) < innerThreshold) {
U8CPU alpha = SkColorGetA(source);
if (alpha == 0)
alpha = 1;
float scale = (float)innerThreshold / alpha;
output_color = SkColorSetARGB(innerThreshold,
SkColorGetR(source) * scale,
SkColorGetG(source) * scale,
SkColorGetB(source) * scale);
}
} else {
if (SkColorGetA(source) > outerThreshold) {
float scale = (float)outerThreshold / SkColorGetA(source);
output_color = SkColorSetARGB(outerThreshold,
SkColorGetR(source) * scale,
SkColorGetG(source) * scale,
SkColorGetB(source) * scale);
}
}
dptr[y * dst->width() + x] = output_color;
}
}
return true;
}

2
tests/GLProgramsTest.cpp
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@ -251,6 +251,7 @@ DEFINE_GPUTESTCLASS("GLPrograms", GLProgramsTestClass, GLProgramsTest)
// in the unit that could pass pointers to functions from the unit out to other translation units!
// We force some of the effects that would otherwise be discarded to link here.
#include "SkAlphaThresholdFilter.h"
#include "SkLightingImageFilter.h"
#include "SkMagnifierImageFilter.h"
#include "SkColorMatrixFilter.h"
@ -259,6 +260,7 @@ void forceLinking();
void forceLinking() {
SkLightingImageFilter::CreateDistantLitDiffuse(SkPoint3(0,0,0), 0, 0, 0);
SkAlphaThresholdFilter::Create(SkRegion(), .5, .5);
SkMagnifierImageFilter mag(SkRect::MakeWH(SK_Scalar1, SK_Scalar1), SK_Scalar1);
GrConfigConversionEffect::Create(NULL,
false,