Implement approx-match support in image filter saveLayer() offscreen.

src/effects/SkMagnifierImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkMagnifierImageFilter.h"
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkValidationUtils.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 #if SK_SUPPORT_GPU
 #include "GrInvariantOutput.h"
 #include "effects/GrSingleTextureEffect.h"
 #include "gl/GrGLProcessor.h"
 #include "gl/GrGLSL.h"
 #include "gl/GrGLTexture.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 class GrMagnifierEffect : public GrSingleTextureEffect {
 
 public:
     static GrFragmentProcessor* Create(GrTexture* texture,
+                                       const SkRect& bounds,
                                        float xOffset,
                                        float yOffset,
                                        float xInvZoom,
                                        float yInvZoom,
                                        float xInvInset,
                                        float yInvInset) {
         return SkNEW_ARGS(GrMagnifierEffect, (texture,
+                                              bounds,
                                               xOffset,
                                               yOffset,
                                               xInvZoom,
                                               yInvZoom,
                                               xInvInset,
                                               yInvInset));
     }
 
     virtual ~GrMagnifierEffect() {};
 
     const char* name() const override { return "Magnifier"; }
 
     void getGLProcessorKey(const GrGLCaps&, GrProcessorKeyBuilder*) const override;
 
     GrGLFragmentProcessor* createGLInstance() const override;
 
+    const SkRect& bounds() const { return fBounds; }    // Bounds of source image.
+    // Offset to apply to zoomed pixels, (srcRect position / texture size).
     float x_offset() const { return fXOffset; }
     float y_offset() const { return fYOffset; }
+
+    // Scale to apply to zoomed pixels (srcRect size / bounds size).
     float x_inv_zoom() const { return fXInvZoom; }
     float y_inv_zoom() const { return fYInvZoom; }
+
+    // 1/radius over which to transition from unzoomed to zoomed pixels (bounds size / inset).
     float x_inv_inset() const { return fXInvInset; }
     float y_inv_inset() const { return fYInvInset; }
 
 private:
     GrMagnifierEffect(GrTexture* texture,
+                      const SkRect& bounds,
                       float xOffset,
                       float yOffset,
                       float xInvZoom,
                       float yInvZoom,
                       float xInvInset,
                       float yInvInset)
         : GrSingleTextureEffect(texture, GrCoordTransform::MakeDivByTextureWHMatrix(texture))
+        , fBounds(bounds)
         , fXOffset(xOffset)
         , fYOffset(yOffset)
         , fXInvZoom(xInvZoom)
         , fYInvZoom(yInvZoom)
         , fXInvInset(xInvInset)
         , fYInvInset(yInvInset) {
         this->initClassID<GrMagnifierEffect>();
     }
 
     bool onIsEqual(const GrFragmentProcessor&) const override;
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override;
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
 
+    SkRect fBounds;
     float fXOffset;
     float fYOffset;
     float fXInvZoom;
     float fYInvZoom;
     float fXInvInset;
     float fYInvInset;
 
     typedef GrSingleTextureEffect INHERITED;
 };
 
@@ skipping 10 matching lines @@
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) override;
 
     void setData(const GrGLProgramDataManager&, const GrProcessor&) override;
 
 private:
     UniformHandle       fOffsetVar;
     UniformHandle       fInvZoomVar;
     UniformHandle       fInvInsetVar;
+    UniformHandle       fBoundsVar;
 
     typedef GrGLFragmentProcessor INHERITED;
 };
 
 GrGLMagnifierEffect::GrGLMagnifierEffect(const GrProcessor&) {
 }
 
 void GrGLMagnifierEffect::emitCode(GrGLFPBuilder* builder,
                                    const GrFragmentProcessor&,
                                    const char* outputColor,
                                    const char* inputColor,
                                    const TransformedCoordsArray& coords,
                                    const TextureSamplerArray& samplers) {
     fOffsetVar = builder->addUniform(
         GrGLProgramBuilder::kFragment_Visibility |
         GrGLProgramBuilder::kVertex_Visibility,
         kVec2f_GrSLType, kDefault_GrSLPrecision, "Offset");
     fInvZoomVar = builder->addUniform(
         GrGLProgramBuilder::kFragment_Visibility |
         GrGLProgramBuilder::kVertex_Visibility,
         kVec2f_GrSLType, kDefault_GrSLPrecision, "InvZoom");
     fInvInsetVar = builder->addUniform(
         GrGLProgramBuilder::kFragment_Visibility |
         GrGLProgramBuilder::kVertex_Visibility,
         kVec2f_GrSLType, kDefault_GrSLPrecision, "InvInset");
+    fBoundsVar = builder->addUniform(
+        GrGLProgramBuilder::kFragment_Visibility |
+        GrGLProgramBuilder::kVertex_Visibility,
+        kVec4f_GrSLType, kDefault_GrSLPrecision, "Bounds");
 
     GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
     SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 0);
     fsBuilder->codeAppendf("\t\tvec2 coord = %s;\n", coords2D.c_str());
     fsBuilder->codeAppendf("\t\tvec2 zoom_coord = %s + %s * %s;\n",
                            builder->getUniformCStr(fOffsetVar),
                            coords2D.c_str(),
                            builder->getUniformCStr(fInvZoomVar));
-
-    fsBuilder->codeAppend("\t\tvec2 delta = min(coord, vec2(1.0, 1.0) - coord);\n");
-
+    const char* bounds = builder->getUniformCStr(fBoundsVar);
+    fsBuilder->codeAppendf("\t\tvec2 delta = (coord - %s.xy) * %s.zw;\n", bounds, bounds);
+    fsBuilder->codeAppendf("\t\tdelta = min(delta, vec2(1.0, 1.0) - delta);\n");
     fsBuilder->codeAppendf("\t\tdelta = delta * %s;\n", builder->getUniformCStr(fInvInsetVar));
 
     fsBuilder->codeAppend("\t\tfloat weight = 0.0;\n");
     fsBuilder->codeAppend("\t\tif (delta.s < 2.0 && delta.t < 2.0) {\n");
     fsBuilder->codeAppend("\t\t\tdelta = vec2(2.0, 2.0) - delta;\n");
     fsBuilder->codeAppend("\t\t\tfloat dist = length(delta);\n");
     fsBuilder->codeAppend("\t\t\tdist = max(2.0 - dist, 0.0);\n");
     fsBuilder->codeAppend("\t\t\tweight = min(dist * dist, 1.0);\n");
     fsBuilder->codeAppend("\t\t} else {\n");
     fsBuilder->codeAppend("\t\t\tvec2 delta_squared = delta * delta;\n");
@@ skipping 10 matching lines @@
     GrGLSLMulVarBy4f(&modulate, outputColor, inputColor);
     fsBuilder->codeAppend(modulate.c_str());
 }
 
 void GrGLMagnifierEffect::setData(const GrGLProgramDataManager& pdman,
                                   const GrProcessor& effect) {
     const GrMagnifierEffect& zoom = effect.cast<GrMagnifierEffect>();
     pdman.set2f(fOffsetVar, zoom.x_offset(), zoom.y_offset());
     pdman.set2f(fInvZoomVar, zoom.x_inv_zoom(), zoom.y_inv_zoom());
     pdman.set2f(fInvInsetVar, zoom.x_inv_inset(), zoom.y_inv_inset());
+    pdman.set4f(fBoundsVar, zoom.bounds().x(), zoom.bounds().y(),
+                            zoom.bounds().width(), zoom.bounds().height());
 }
 
 /////////////////////////////////////////////////////////////////////
 
 void GrMagnifierEffect::getGLProcessorKey(const GrGLCaps& caps,
                                           GrProcessorKeyBuilder* b) const {
     GrGLMagnifierEffect::GenKey(*this, caps, b);
 }
 
 GrGLFragmentProcessor* GrMagnifierEffect::createGLInstance() const {
@@ skipping 11 matching lines @@
     const int kMaxHeight = 200;
     const int kMaxInset = 20;
     uint32_t width = random->nextULessThan(kMaxWidth);
     uint32_t height = random->nextULessThan(kMaxHeight);
     uint32_t x = random->nextULessThan(kMaxWidth - width);
     uint32_t y = random->nextULessThan(kMaxHeight - height);
     uint32_t inset = random->nextULessThan(kMaxInset);
 
     GrFragmentProcessor* effect = GrMagnifierEffect::Create(
         texture,
+        SkRect::MakeWH(SkIntToScalar(kMaxWidth), SkIntToScalar(kMaxHeight)),
         (float) width / texture->width(),
         (float) height / texture->height(),
         texture->width() / (float) x,
         texture->height() / (float) y,
         (float) inset / texture->width(),
         (float) inset / texture->height());
     SkASSERT(effect);
     return effect;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 bool GrMagnifierEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
     const GrMagnifierEffect& s = sBase.cast<GrMagnifierEffect>();
-    return (this->fXOffset == s.fXOffset &&
+    return (this->fBounds == s.fBounds &&
+            this->fXOffset == s.fXOffset &&
             this->fYOffset == s.fYOffset &&
             this->fXInvZoom == s.fXInvZoom &&
             this->fYInvZoom == s.fYInvZoom &&
             this->fXInvInset == s.fXInvInset &&
             this->fYInvInset == s.fYInvInset);
 }
 
 void GrMagnifierEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
     this->updateInvariantOutputForModulation(inout);
 }
@@ skipping 17 matching lines @@
 
 
 SkMagnifierImageFilter::SkMagnifierImageFilter(const SkRect& srcRect, SkScalar inset,
                                                SkImageFilter* input)
     : INHERITED(1, &input), fSrcRect(srcRect), fInset(inset) {
     SkASSERT(srcRect.x() >= 0 && srcRect.y() >= 0 && inset >= 0);
 }
 
 #if SK_SUPPORT_GPU
 bool SkMagnifierImageFilter::asFragmentProcessor(GrFragmentProcessor** fp, GrTexture* texture,
-                                                 const SkMatrix&, const SkIRect&) const {
+                                                 const SkMatrix&, const SkIRect&bounds) const {
     if (fp) {
-        SkScalar yOffset = (texture->origin() == kTopLeft_GrSurfaceOrigin) ? fSrcRect.y() :
-                           (texture->height() - (fSrcRect.y() + fSrcRect.height()));
+        SkScalar yOffset = texture->origin() == kTopLeft_GrSurfaceOrigin ? fSrcRect.y() :
+           texture->height() - fSrcRect.height() * texture->height() / bounds.height()
+                             - fSrcRect.y();
+        int boundsY = (texture->origin() == kTopLeft_GrSurfaceOrigin) ? bounds.y() :
+                      (texture->height() - bounds.height());
+        SkRect effectBounds = SkRect::MakeXYWH(
+            SkIntToScalar(bounds.x()) / texture->width(),
+            SkIntToScalar(boundsY) / texture->height(),
+            SkIntToScalar(texture->width()) / bounds.width(),
+            SkIntToScalar(texture->height()) / bounds.height());
         SkScalar invInset = fInset > 0 ? SkScalarInvert(fInset) : SK_Scalar1;
         *fp = GrMagnifierEffect::Create(texture,
+                                        effectBounds,
                                         fSrcRect.x() / texture->width(),
                                         yOffset / texture->height(),
-                                        fSrcRect.width() / texture->width(),
-                                        fSrcRect.height() / texture->height(),
-                                        texture->width() * invInset,
-                                        texture->height() * invInset);
+                                        fSrcRect.width() / bounds.width(),
+                                        fSrcRect.height() / bounds.height(),
+                                        bounds.width() * invInset,
+                                        bounds.height() * invInset);
     }
     return true;
 }
 #endif
 
 SkFlattenable* SkMagnifierImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
     SkRect src;
     buffer.readRect(&src);
     return Create(src, buffer.readScalar(), common.getInput(0));
@@ skipping 73 matching lines @@
 
 #ifndef SK_IGNORE_TO_STRING
 void SkMagnifierImageFilter::toString(SkString* str) const {
     str->appendf("SkMagnifierImageFilter: (");
     str->appendf("src: (%f,%f,%f,%f) ",
                  fSrcRect.fLeft, fSrcRect.fTop, fSrcRect.fRight, fSrcRect.fBottom);
     str->appendf("inset: %f", fInset);
     str->append(")");
 }
 #endif