Fast blurred rectangles on GPU

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index fa31743bb3adac1033b2da39725ea30bfe57bc62..f51872a260224b4f5bd15f845c974de2f8ac2370 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -19,7 +19,10 @@
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrTexture.h"
+#include "GrEffect.h"
+#include "gl/GrGLEffect.h"
 #include "effects/GrSimpleTextureEffect.h"
+#include "GrTBackendEffectFactory.h"
 #include "SkGrPixelRef.h"
 #endif
 
@@ -37,6 +40,11 @@ public:
                                   const SkIRect& clipBounds,
                                   const SkMatrix& ctm,
                                   SkRect* maskRect) const SK_OVERRIDE;
+    virtual bool directFilterMaskGPU(GrContext* context,
+                                     GrPaint* grp,
+                                     const SkStrokeRec& strokeRec,
+                                     const SkPath& path) const SK_OVERRIDE;
+
     virtual bool filterMaskGPU(GrTexture* src,
                                const SkMatrix& ctm,
                                const SkRect& maskRect,
@@ -503,6 +511,274 @@ void SkBlurMaskFilterImpl::flatten(SkFlattenableWriteBuffer& buffer) const {
 
 #if SK_SUPPORT_GPU
 
+class GrGLRectBlurEffect;
+
+class GrRectBlurEffect : public GrEffect {
+public:
+    virtual ~GrRectBlurEffect();
+
+    static const char* Name() { return "RectBlur"; }
+
+    typedef GrGLRectBlurEffect GLEffect;
+
+    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
+    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+
+    /**
+     * Create a simple filter effect with custom bicubic coefficients.
+     */
+    static GrEffectRef* Create(GrContext *context, const SkRect& rect, 
+                               float sigma) {
+        GrTexture *horizontalScanline, *verticalScanline;
+        bool createdScanlines = CreateScanlineTextures(context, sigma, 
+                                                       SkScalarCeilToInt(rect.width()),
+                                                       SkScalarCeilToInt(rect.height()),
+                                                       &horizontalScanline, &verticalScanline);
+        if (!createdScanlines) {
+            return NULL;
+        }
+        AutoEffectUnref effect(SkNEW_ARGS(GrRectBlurEffect, (rect, sigma, 
+                                                             horizontalScanline, verticalScanline)));
+        return CreateEffectRef(effect);    
+    }
+    
+    unsigned int getWidth() const { return fWidth; }
+    unsigned int getHeight() const { return fHeight; }
+    float getSigma() const { return fSigma; }
+
+private:
+    GrRectBlurEffect(const SkRect& rect, float sigma, 
+                     GrTexture *horizontal_scanline, GrTexture *vertical_scanline);
+    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
+    
+    static bool CreateScanlineTextures(GrContext *context, float sigma,
+                                       unsigned int width, unsigned int height,
+                                       GrTexture **horizontalScanline,
+                                       GrTexture **verticalScanline);
+    
+    unsigned int fWidth, fHeight;
+    float fSigma;
+    GrTextureAccess  fHorizontalScanlineAccess;
+    GrTextureAccess  fVerticalScanlineAccess;
+    GrCoordTransform fTrivialTransform;
+
+    GR_DECLARE_EFFECT_TEST;
+
+    typedef GrEffect INHERITED;
+};
+
+class GrGLRectBlurEffect : public GrGLEffect {
+public:
+    GrGLRectBlurEffect(const GrBackendEffectFactory& factory,
+                      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:
+    typedef GrGLUniformManager::UniformHandle        UniformHandle;
+
+    UniformHandle       fWidthUni;
+    UniformHandle       fHeightUni;
+
+    typedef GrGLEffect INHERITED;
+};
+
+GrGLRectBlurEffect::GrGLRectBlurEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
+    : INHERITED(factory) {
+}
+
+void GrGLRectBlurEffect::emitCode(GrGLShaderBuilder* builder,
+                                 const GrDrawEffect&,
+                                 EffectKey key,
+                                 const char* outputColor,
+                                 const char* inputColor,
+                                 const TransformedCoordsArray& coords,
+                                 const TextureSamplerArray& samplers) {
+    
+    SkString texture_coords = builder->ensureFSCoords2D(coords, 0);
+    
+    if (inputColor) {
+        builder->fsCodeAppendf("\tvec4 src=%s;\n", inputColor);
+    } else {
+        builder->fsCodeAppendf("\tvec4 src=vec4(1)\n;");
+    }
+    
+    builder->fsCodeAppendf("\tvec4 horiz = ");
+    builder->fsAppendTextureLookup( samplers[0], texture_coords.c_str() );
+    builder->fsCodeAppendf(";\n");
+    builder->fsCodeAppendf("\tvec4 vert = ");
+    builder->fsAppendTextureLookup( samplers[1], texture_coords.c_str() );
+    builder->fsCodeAppendf(";\n");
+    
+    builder->fsCodeAppendf("\tfloat final = (horiz*vert).r;\n");
+    builder->fsCodeAppendf("\t%s = final*src;\n", outputColor);
+    // builder->fsCodeAppendf("\t%s = vec4(%s.r,%s.g,0,1);\n", outputColor, texture_coords.c_str(), texture_coords.c_str());

[bsalomon, 2014/01/27 19:07:00]

should we remove this line?

+}
+
+void GrGLRectBlurEffect::setData(const GrGLUniformManager& uman,
+                                const GrDrawEffect& drawEffect) {
+}
+
+bool GrRectBlurEffect::CreateScanlineTextures(GrContext *context, float sigma,
+                                              unsigned int width, unsigned int height,
+                                              GrTexture **horizontalScanline,
+                                              GrTexture **verticalScanline) {
+    GrTextureParams params;
+    GrTextureDesc texDesc;
+    
+    unsigned int profile_size = SkScalarFloorToInt(6*sigma);
+    
+    texDesc.fWidth = width;
+    texDesc.fHeight = 1;
+    texDesc.fConfig = kAlpha_8_GrPixelConfig;
+    
+    static const GrCacheID::Domain gBlurProfileDomain = GrCacheID::GenerateDomain();
+    GrCacheID::Key key;
+    memset(&key, 0, sizeof(key));
+    key.fData32[0] = profile_size;
+    key.fData32[1] = width;
+    key.fData32[2] = 1;
+    GrCacheID horizontalCacheID(gBlurProfileDomain, key);

[bsalomon, 2014/01/27 19:07:00]

should we make both the horizontal and vertical texture be 1 pixel high so that
we can use the same cache entries for both?

+    
+    uint8_t *profile = NULL;
+    SkAutoTDeleteArray<uint8_t> ada(profile);
+    
+    *horizontalScanline = context->findAndRefTexture(texDesc, horizontalCacheID, &params);
+    
+    if (NULL == *horizontalScanline) {
+    
+        SkBlurMask::ComputeBlurProfile(sigma, &profile);
+        
+        SkAutoTMalloc<uint8_t> horizontalPixels(width);
+        SkBlurMask::ComputeBlurredScanline(horizontalPixels, profile, width, sigma);
+    
+        *horizontalScanline = context->createTexture(&params, texDesc, horizontalCacheID, 
+                                                     horizontalPixels, 0);
+                                                     
+        if (NULL == *horizontalScanline) {
+            return false;
+        }
+    }
+    
+    texDesc.fWidth = 1;
+    texDesc.fHeight = height;
+    key.fData32[1] = 1;
+    key.fData32[2] = height;
+    GrCacheID verticalCacheID(gBlurProfileDomain, key);
+    
+    *verticalScanline = context->findAndRefTexture(texDesc, verticalCacheID, &params);
+    if (NULL == *verticalScanline) {
+        if (NULL == profile) {
+            SkBlurMask::ComputeBlurProfile(sigma, &profile);
+        }
+        
+        SkAutoTMalloc<uint8_t> verticalPixels(height);
+        SkBlurMask::ComputeBlurredScanline(verticalPixels, profile, height, sigma);
+    
+        *verticalScanline = context->createTexture(&params, texDesc, verticalCacheID, 
+                                                   verticalPixels, 0);
+                                                     
+        if (NULL == *verticalScanline) {
+            return false;
+        }
+        
+    }
+    return true;
+}
+
+GrRectBlurEffect::GrRectBlurEffect(const SkRect& rect, float sigma,
+                                   GrTexture *horizontal_scanline, GrTexture *vertical_scanline)
+  : INHERITED(), 
+    fWidth(horizontal_scanline->width()),
+    fHeight(vertical_scanline->width()),
+    fSigma(sigma),
+    fHorizontalScanlineAccess(horizontal_scanline),
+    fVerticalScanlineAccess(vertical_scanline) {
+    SkMatrix mat;
+    mat.setRectToRect(rect, SkRect::MakeWH(1,1), SkMatrix::kFill_ScaleToFit);
+    fTrivialTransform = GrCoordTransform(kLocal_GrCoordSet, mat);

[bsalomon, 2014/01/27 19:07:00]

Is this the right name for this now (trivial)?

+    this->addTextureAccess(&fHorizontalScanlineAccess);  
+    this->addTextureAccess(&fVerticalScanlineAccess);  
+    this->addCoordTransform(&fTrivialTransform);
+}
+
+GrRectBlurEffect::~GrRectBlurEffect() {
+}
+
+const GrBackendEffectFactory& GrRectBlurEffect::getFactory() const {
+    return GrTBackendEffectFactory<GrRectBlurEffect>::getInstance();
+}
+
+bool GrRectBlurEffect::onIsEqual(const GrEffect& sBase) const {
+    const GrRectBlurEffect& s = CastEffect<GrRectBlurEffect>(sBase);
+    return this->getWidth() == s.getWidth() &&
+           this->getHeight() == s.getHeight() &&
+           this->getSigma() == s.getSigma();
+}
+
+void GrRectBlurEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
+    *validFlags = 0;
+    return;
+}
+
+GR_DEFINE_EFFECT_TEST(GrRectBlurEffect);
+
+GrEffectRef* GrRectBlurEffect::TestCreate(SkRandom* random,
+                                         GrContext* context,
+                                         const GrDrawTargetCaps&,
+                                         GrTexture**) {
+    float sigma = random->nextRangeF(3,8);
+    float width = random->nextRangeF(200,300);
+    float height = random->nextRangeF(200,300);
+    return GrRectBlurEffect::Create(context, SkRect::MakeWH(width, height), sigma);
+}
+
+
+bool SkBlurMaskFilterImpl::directFilterMaskGPU(GrContext* context,
+                                               GrPaint* grp,
+                                               const SkStrokeRec& strokeRec,
+                                               const SkPath& path) const {
+    if (fBlurStyle != SkBlurMaskFilter::kNormal_BlurStyle) {
+        return false;
+    }
+    
+    SkRect rect;
+    if (!path.isRect(&rect)) {
+        return false;
+    }
+    
+    if (!strokeRec.isFillStyle()) {
+        return false;
+    }
+    
+    GrContext::AutoMatrix am;
+    if (!am.setIdentity(context, grp)) {
+       return false;
+    }
+
+    SkMatrix ctm = context->getMatrix();

[bsalomon, 2014/01/27 19:07:00]

this is now guaranteed to be identity because of the AutoMatrix above. Why don't
we move AutoMatrix down to be right above addCoverageEffect. Then I think we get
the right radius adjustment and also ensure the AutoMatrix is the last thing
that gets a chance to fail (since it whacks the GrPaint when it succeeds).

+    SkScalar xformedSigma = this->computeXformedSigma(ctm);
+    rect.outset(3*xformedSigma, 3*xformedSigma);
+    
+    SkAutoTUnref<GrEffectRef> effect(GrRectBlurEffect::Create(
+            context, rect, xformedSigma));
+    if (!effect) {
+        return false;
+    }
+    grp->addCoverageEffect(effect);
+    
+    context->drawRect(*grp, rect);
+    // context->drawRectToRect(*grp, rect, SkRect::MakeWH(1,1));
+    return true;
+}
+
 bool SkBlurMaskFilterImpl::canFilterMaskGPU(const SkRect& srcBounds,
                                             const SkIRect& clipBounds,
                                             const SkMatrix& ctm,