Add AlphaThreshold filter.
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
diff --git a/gm/imagealphathreshold.cpp b/gm/imagealphathreshold.cpp
new file mode 100644
index 0000000..2839744
--- /dev/null
+++ b/gm/imagealphathreshold.cpp
@@ -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);
+
+}
diff --git a/gyp/effects.gypi b/gyp/effects.gypi
index 74cfdda..21e02e4 100644
--- a/gyp/effects.gypi
+++ b/gyp/effects.gypi
@@ -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',
diff --git a/gyp/gmslides.gypi b/gyp/gmslides.gypi
index 40eb101..8e50eb0 100644
--- a/gyp/gmslides.gypi
+++ b/gyp/gmslides.gypi
@@ -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',
diff --git a/gyp/public_headers.gypi b/gyp/public_headers.gypi
index a9ef4dd..b42623f 100644
--- a/gyp/public_headers.gypi
+++ b/gyp/public_headers.gypi
@@ -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',
diff --git a/include/effects/SkAlphaThresholdFilter.h b/include/effects/SkAlphaThresholdFilter.h
new file mode 100644
index 0000000..23af56f
--- /dev/null
+++ b/include/effects/SkAlphaThresholdFilter.h
@@ -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
diff --git a/src/effects/SkAlphaThresholdFilter.cpp b/src/effects/SkAlphaThresholdFilter.cpp
new file mode 100644
index 0000000..a53731f
--- /dev/null
+++ b/src/effects/SkAlphaThresholdFilter.cpp
@@ -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;
+}
diff --git a/tests/GLProgramsTest.cpp b/tests/GLProgramsTest.cpp
index cbf00fd..a1dbea8 100644
--- a/tests/GLProgramsTest.cpp
+++ b/tests/GLProgramsTest.cpp
@@ -251,6 +251,7 @@
// 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() {
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,