alpha threshold bitmap shader
R=reed@google.com
Author: bsalomon@google.com
Review URL: https://chromiumcodereview.appspot.com/23707019
git-svn-id: http://skia.googlecode.com/svn/trunk/src@11122 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/effects/SkBitmapAlphaThresholdShader.cpp b/effects/SkBitmapAlphaThresholdShader.cpp
new file mode 100644
index 0000000..67a3c3f
--- /dev/null
+++ b/effects/SkBitmapAlphaThresholdShader.cpp
@@ -0,0 +1,311 @@
+/*
+ * 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 "SkBitmapAlphaThresholdShader.h"
+
+class BATShader : public SkShader {
+public:
+ SK_DECLARE_INST_COUNT(SkThresholdShader);
+
+ BATShader(const SkBitmap& bitmap, SkRegion region, U8CPU);
+ BATShader(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
+ // We should probably do something here.
+ }
+
+
+ virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE {};
+
+#if SK_SUPPORT_GPU
+ virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint& paint) const SK_OVERRIDE;
+#endif
+
+ SK_DEVELOPER_TO_STRING();
+ SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(BATShader)
+
+private:
+ SkBitmap fBitmap;
+ SkRegion fRegion;
+ U8CPU fThreshold;
+
+ typedef SkShader INHERITED;
+};
+
+SkShader* SkBitmapAlphaThresholdShader::Create(const SkBitmap& bitmap,
+ const SkRegion& region,
+ U8CPU threshold) {
+ SkASSERT(threshold < 256);
+ return SkNEW_ARGS(BATShader, (bitmap, region, threshold));
+}
+
+BATShader::BATShader(const SkBitmap& bitmap, SkRegion region, U8CPU threshold)
+: fBitmap(bitmap)
+, fRegion(region)
+, fThreshold(threshold) {
+};
+
+
+#ifdef SK_DEVELOPER
+void BATShader::toString(SkString* str) const {
+ str->append("BATShader: (");
+
+ fBitmap.toString(str);
+
+ this->INHERITED::toString(str);
+
+ str->append(")");
+}
+#endif
+
+#if SK_SUPPORT_GPU
+#include "GrContext.h"
+#include "GrEffect.h"
+#include "gl/GrGLEffect.h"
+#include "gl/GrGLEffectMatrix.h"
+#include "GrTBackendEffectFactory.h"
+#include "GrTextureAccess.h"
+
+#include "SkGr.h"
+
+/**
+ * Could create specializations for some simple cases:
+ * - The region is empty.
+ * - The region fully contains the bitmap.
+ * - The regions is 1 rect (or maybe a small number of rects).
+ */
+class ThresholdEffect : public GrEffect {
+public:
+ virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE {
+ return GrTBackendEffectFactory<ThresholdEffect>::getInstance();
+ }
+
+ static GrEffectRef* Create(GrTexture* bmpTexture, const SkMatrix& bmpMatrix,
+ GrTexture* maskTexture, const SkMatrix& maskMatrix,
+ U8CPU threshold) {
+ SkScalar thresh = SkIntToScalar(threshold) / 255;
+
+ AutoEffectUnref effect(SkNEW_ARGS(ThresholdEffect, (bmpTexture, bmpMatrix,
+ maskTexture, maskMatrix,
+ thresh)));
+ return CreateEffectRef(effect);
+ }
+
+ virtual void getConstantColorComponents(GrColor* color,
+ uint32_t* validFlags) const SK_OVERRIDE {
+ if ((kA_GrColorComponentFlag & *validFlags) && 0 == GrColorUnpackA(*color)) {
+ return;
+ }
+ *validFlags = 0;
+ return;
+ }
+
+ static const char* Name() { return "Bitmap Alpha Threshold"; }
+
+ class GLEffect : public GrGLEffect {
+ public:
+ GLEffect(const GrBackendEffectFactory& factory,
+ const GrDrawEffect& e)
+ : GrGLEffect(factory)
+ , fBmpMatrix(GrEffect::kLocal_CoordsType)
+ , fMaskMatrix(GrEffect::kLocal_CoordsType)
+ , fPrevThreshold(-SK_Scalar1) {
+ }
+
+ virtual void emitCode(GrGLShaderBuilder* builder,
+ const GrDrawEffect& drawEffect,
+ EffectKey key,
+ const char* outputColor,
+ const char* inputColor,
+ const TextureSamplerArray& samplers) SK_OVERRIDE {
+ SkString bmpCoord;
+ SkString maskCoord;
+
+ GrSLType bmpCoordType = fBmpMatrix.emitCode(builder, key, &bmpCoord, NULL, "Bmp");
+ EffectKey maskMatrixKey = key >> GrGLEffectMatrix::kKeyBits;
+ GrSLType maskCoordType = fMaskMatrix.emitCode(builder,
+ maskMatrixKey,
+ &maskCoord,
+ NULL,
+ "Mask");
+
+ // put bitmap color in "color"
+ builder->fsCodeAppend("\t\tvec4 color = ");
+ builder->fsAppendTextureLookup(samplers[0], bmpCoord.c_str(), bmpCoordType);
+ builder->fsCodeAppend(";\n");
+
+ // put alpha from mask texture in "mask"
+ builder->fsCodeAppend("\t\tfloat mask = ");
+ builder->fsAppendTextureLookup(samplers[1], maskCoord.c_str(), maskCoordType);
+ builder->fsCodeAppend(".a;\n");
+
+ const char* threshold;
+
+ fThresholdUniHandle = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
+ kFloat_GrSLType,
+ "threshold",
+ &threshold);
+ builder->fsCodeAppendf("\t\tfloat thresh = %s;\n", threshold);
+
+ builder->fsCodeAppend("\t\tif (mask < 0.5) {\n"
+ "\t\t\tif (color.a > thresh) {\n"
+ "\t\t\t\tfloat scale = thresh / color.a;\n"
+ "\t\t\t\tcolor.rgb *= scale;\n"
+ "\t\t\t\tcolor.a = thresh;\n"
+ "\t\t\t}\n"
+ "\t\t} else if (color.a < thresh) {\n"
+ "\t\t\tfloat scale = thresh / color.a;\n"
+ "\t\t\tcolor.rgb *= scale;\n"
+ "\t\t\tcolor.a = thresh;\n"
+ "\t\t}\n");
+
+ builder->fsCodeAppend("color = ");
+ SkString outStr;
+ outStr.appendf("\t\t%s = ", outputColor);
+ GrGLSLModulatef<4>(&outStr, inputColor, "color");
+ outStr.append(";\n");
+ builder->fsCodeAppend(outStr.c_str());
+ }
+
+ virtual void setData(const GrGLUniformManager& uman, const GrDrawEffect& e) SK_OVERRIDE {
+ const ThresholdEffect& effect = e.castEffect<ThresholdEffect>();
+ fBmpMatrix.setData(uman, effect.fBmpMatrix, e, effect.fBmpAccess.getTexture());
+ fMaskMatrix.setData(uman, effect.fMaskMatrix, e, effect.fMaskAccess.getTexture());
+ if (fPrevThreshold != effect.fThreshold) {
+ uman.set1f(fThresholdUniHandle, effect.fThreshold);
+ }
+ }
+
+ static inline EffectKey GenKey(const GrDrawEffect& e, const GrGLCaps&) {
+ const ThresholdEffect& effect = e.castEffect<ThresholdEffect>();
+
+ EffectKey bmpMKey = GrGLEffectMatrix::GenKey(effect.fBmpMatrix,
+ e,
+ GrEffect::kLocal_CoordsType,
+ effect.fBmpAccess.getTexture());
+ EffectKey maskMKey = GrGLEffectMatrix::GenKey(effect.fMaskMatrix,
+ e,
+ GrEffect::kLocal_CoordsType,
+ effect.fMaskAccess.getTexture());
+ return bmpMKey | (maskMKey << GrGLEffectMatrix::kKeyBits);
+ }
+
+ private:
+ GrGLEffectMatrix fBmpMatrix;
+ GrGLEffectMatrix fMaskMatrix;
+
+ GrGLUniformManager::UniformHandle fThresholdUniHandle;
+ SkScalar fPrevThreshold;
+ };
+
+ GR_DECLARE_EFFECT_TEST;
+
+private:
+ ThresholdEffect(GrTexture* bmpTexture, const SkMatrix& bmpMatrix,
+ GrTexture* maskTexture, const SkMatrix& maskMatrix,
+ SkScalar threshold)
+ : fBmpAccess(bmpTexture, GrTextureParams())
+ , fMaskAccess(maskTexture, GrTextureParams())
+ , fBmpMatrix(bmpMatrix)
+ , fMaskMatrix(maskMatrix)
+ , fThreshold(threshold) {
+ this->addTextureAccess(&fBmpAccess);
+ this->addTextureAccess(&fMaskAccess);
+ }
+
+ virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
+ const ThresholdEffect& e = CastEffect<ThresholdEffect>(other);
+ return e.fBmpAccess.getTexture() == fBmpAccess.getTexture() &&
+ e.fMaskAccess.getTexture() == fMaskAccess.getTexture() &&
+ e.fBmpMatrix == fBmpMatrix &&
+ e.fMaskMatrix == fMaskMatrix &&
+ e.fThreshold == fThreshold;
+ }
+
+ GrTextureAccess fBmpAccess;
+ GrTextureAccess fMaskAccess;
+
+ SkMatrix fBmpMatrix;
+ SkMatrix fMaskMatrix;
+
+ SkScalar fThreshold;
+};
+
+GR_DEFINE_EFFECT_TEST(ThresholdEffect);
+
+GrEffectRef* ThresholdEffect::TestCreate(SkMWCRandom* rand,
+ GrContext*,
+ const GrDrawTargetCaps&,
+ GrTexture* textures[]) {
+ GrTexture* bmpTex = textures[GrEffectUnitTest::kSkiaPMTextureIdx];
+ GrTexture* maskTex = textures[GrEffectUnitTest::kAlphaTextureIdx];
+ U8CPU thresh = rand->nextU() % 0xff;
+ return ThresholdEffect::Create(bmpTex, SkMatrix::I(), maskTex, SkMatrix::I(), thresh);
+}
+
+GrEffectRef* BATShader::asNewEffect(GrContext* context, const SkPaint& paint) const {
+ SkMatrix localInverse;
+ if (!this->getLocalMatrix().invert(&localInverse)) {
+ return NULL;
+ }
+
+ GrTextureDesc maskDesc;
+ if (context->isConfigRenderable(kAlpha_8_GrPixelConfig)) {
+ maskDesc.fConfig = kAlpha_8_GrPixelConfig;
+ } else {
+ maskDesc.fConfig = kRGBA_8888_GrPixelConfig;
+ }
+ maskDesc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
+ const SkIRect& bounds = fRegion.getBounds();
+ // Add one pixel of border to ensure that clamp mode will be all zeros
+ // the outside.
+ maskDesc.fWidth = bounds.width() + 2;
+ maskDesc.fHeight = bounds.height() + 2;
+ GrAutoScratchTexture ast(context, maskDesc, GrContext::kApprox_ScratchTexMatch);
+ GrTexture* maskTexture = ast.texture();
+ if (NULL == maskTexture) {
+ return false;
+ }
+
+ GrPaint grPaint;
+ grPaint.setBlendFunc(kOne_GrBlendCoeff, kZero_GrBlendCoeff);
+ SkRegion::Iterator iter(fRegion);
+ context->setRenderTarget(maskTexture->asRenderTarget());
+ context->clear(NULL, 0x0);
+
+ // offset to ensure border is zero on top/left
+ SkMatrix matrix;
+ matrix.setTranslate(SK_Scalar1, SK_Scalar1);
+ context->setMatrix(matrix);
+
+ while (!iter.done()) {
+ SkRect rect = SkRect::MakeFromIRect(iter.rect());
+ context->drawRect(grPaint, rect);
+ iter.next();
+ }
+
+ GrTexture* bmpTexture = GrLockAndRefCachedBitmapTexture(context, fBitmap, NULL);
+ if (NULL == bmpTexture) {
+ return NULL;
+ }
+
+ SkMatrix bmpMatrix = localInverse;
+ bmpMatrix.postIDiv(bmpTexture->width(), bmpTexture->height());
+
+ SkMatrix maskMatrix = localInverse;
+ // compensate for the border
+ maskMatrix.postTranslate(SK_Scalar1, SK_Scalar1);
+ maskMatrix.postIDiv(maskTexture->width(), maskTexture->height());
+
+ GrEffectRef* effect = ThresholdEffect::Create(bmpTexture, bmpMatrix,
+ maskTexture, maskMatrix,
+ fThreshold);
+
+ GrUnlockAndUnrefCachedBitmapTexture(bmpTexture);
+
+ return effect;
+}
+
+#endif
diff --git a/gpu/SkGpuDevice.cpp b/gpu/SkGpuDevice.cpp
index 571b8a0..ea8a06e 100644
--- a/gpu/SkGpuDevice.cpp
+++ b/gpu/SkGpuDevice.cpp
@@ -535,6 +535,11 @@
return skPaint2GrPaintNoShader(dev, skPaint, false, constantColor, grPaint);
}
+ // SkShader::asNewEffect() may do offscreen rendering. Setup default drawing state
+ // Also require shader to set the render target .
+ GrContext::AutoWideOpenIdentityDraw awo(dev->context(), NULL);
+ GrContext::AutoRenderTarget(dev->context(), NULL);
+
// setup the shader as the first color effect on the paint
SkAutoTUnref<GrEffectRef> effect(shader->asNewEffect(dev->context(), skPaint));
if (NULL != effect.get()) {
