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

Currently, the GPU-side image filter implementation creates
exact-match textures for the offscreen backing stores for
saveLayer().  This is because several filters have GPU
implementations which depend on the texture coordinates
being 0..1.

The fix is three-fold:

1) Store the actual requested size in the SkGpuDevice, so
that when wrapping it in an SkBitmap for passing to
filterImage(), we can give it the original size.
2) Fix the filters (SkMagnifierImageFilter,
SkLightingImageFilter, SkMatrixConvolutionImageFilter,
SkMatrixImageFilter) whose GPU implementation depends on
0..1 texture coordinates.
3) Remove the exception for GPU-side image filters in
SkCanvas::internalSaveLayer().

For the lighting filters, there were two bugs which were
cancelling each other out: the sobel filter matrix was
being computed upside down, but then we'd negate the
resulting normal. This worked fine in the exact-match case,
but in the approx-match case we'd sample garbage along
the edge pixels. Also, we never implemented the edge pixels
according to spec in the GPU case. It requires a
different fragment shader for each edge of the nine-patch,
which meant we couldn't use asFragmentProcessor(), and had
to implement the drawing via a filterImageGPU() override.
In order to avoid polluting the public API, I inserted a
new base class, SkLightingImageFilterInternal above
Sk[Diffuse|Specular]LightingImageFilter to handle the
implementation.

For the SkMatrixConvolutionImageFilter, it seems the
GLSL clamp() function occasionally returns values outside
the clamped range, resulting in access of garbage
texels even in GL_NEAREST. The fix here is to clamp to a
rect inset by half a texel. There was also a bug in
the unpremultiply step when fConvolveAlpha is false.

For SkMatrixImageFilter, the fix was to make the generic
draw path be more careful about when to use texture domain.
If the bitmap already has a texture, use texture domain
if the srcRect is smaller than the entire texture (not
the entire bitmap).

N.B.: this change will cause some minor pixel diffs in the
GPU results of the following GMs (and possibly more):
matriximagefilter, matrixconvolution, imagefiltersscaled,
lighting, imagemagnifier, filterfastbounds,
complexclip_aa_Layer_invert, complexclip_aa_layer,
complexclip_bw_layer_invert, complexclip_bw_layer.

BUG=skia:3532

Committed: https://skia.googlesource.com/skia/+/b97dafefe63ea0a1bbce8e8b209f4920983fb8b9

Committed: https://skia.googlesource.com/skia/+/f5f8518fe0bbd2703e4ffc1b11ad7b4312ff7641

Committed: https://skia.googlesource.com/skia/+/46112cf2a7c7307f1c9eebb5f881cbda15aa460c

Review URL: https://codereview.chromium.org/1034733002

2 files changed, 399 insertions, 96 deletions

diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index 72dcf64c58..972d9ac68b 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -277,7 +277,136 @@ void writePoint3(const SkPoint3& point, SkWriteBuffer& buffer) {
     buffer.writeScalar(point.fZ);
 };
 
-class SkDiffuseLightingImageFilter : public SkLightingImageFilter {
+enum BoundaryMode {
+    kTopLeft_BoundaryMode,
+    kTop_BoundaryMode,
+    kTopRight_BoundaryMode,
+    kLeft_BoundaryMode,
+    kInterior_BoundaryMode,
+    kRight_BoundaryMode,
+    kBottomLeft_BoundaryMode,
+    kBottom_BoundaryMode,
+    kBottomRight_BoundaryMode,
+
+    kBoundaryModeCount,
+};
+
+class SkLightingImageFilterInternal : public SkLightingImageFilter {
+protected:
+    SkLightingImageFilterInternal(SkLight* light,
+                                  SkScalar surfaceScale,
+                                  SkImageFilter* input,
+                                  const CropRect* cropRect)
+      : INHERITED(light, surfaceScale, input, cropRect) {}
+
+#if SK_SUPPORT_GPU
+    bool canFilterImageGPU() const override { return true; }
+    bool filterImageGPU(Proxy*, const SkBitmap& src, const Context&,
+                        SkBitmap* result, SkIPoint* offset) const override;
+    virtual GrFragmentProcessor* getFragmentProcessor(GrTexture*,
+                                                      const SkMatrix&,
+                                                      const SkIRect& bounds,
+                                                      BoundaryMode boundaryMode) const = 0;
+#endif
+private:
+#if SK_SUPPORT_GPU
+    void drawRect(GrContext* context,
+                  GrTexture* src,
+                  GrTexture* dst,
+                  const SkMatrix& matrix,
+                  const GrClip& clip,
+                  const SkRect& dstRect,
+                  BoundaryMode boundaryMode,
+                  const SkIRect& bounds) const;
+#endif
+    typedef SkLightingImageFilter INHERITED;
+};
+
+#if SK_SUPPORT_GPU
+void SkLightingImageFilterInternal::drawRect(GrContext* context,
+                                             GrTexture* src,
+                                             GrTexture* dst,
+                                             const SkMatrix& matrix,
+                                             const GrClip& clip,
+                                             const SkRect& dstRect,
+                                             BoundaryMode boundaryMode,
+                                             const SkIRect& bounds) const {
+    SkRect srcRect = dstRect.makeOffset(SkIntToScalar(bounds.x()), SkIntToScalar(bounds.y()));
+    GrFragmentProcessor* fp = this->getFragmentProcessor(src, matrix, bounds, boundaryMode);
+    GrPaint paint;
+    paint.addColorProcessor(fp)->unref();
+    context->drawNonAARectToRect(dst->asRenderTarget(), clip, paint, SkMatrix::I(),
+                                 dstRect, srcRect);
+}
+
+bool SkLightingImageFilterInternal::filterImageGPU(Proxy* proxy,
+                                                   const SkBitmap& src,
+                                                   const Context& ctx,
+                                                   SkBitmap* result,
+                                                   SkIPoint* offset) const {
+    SkBitmap input = src;
+    SkIPoint srcOffset = SkIPoint::Make(0, 0);
+    if (this->getInput(0) &&
+        !this->getInput(0)->getInputResultGPU(proxy, src, ctx, &input, &srcOffset)) {
+        return false;
+    }
+    SkIRect bounds;
+    if (!this->applyCropRect(ctx, proxy, input, &srcOffset, &bounds, &input)) {
+        return false;
+    }
+    SkRect dstRect = SkRect::MakeWH(SkIntToScalar(bounds.width()),
+                                    SkIntToScalar(bounds.height()));
+    GrTexture* srcTexture = input.getTexture();
+    GrContext* context = srcTexture->getContext();
+
+    GrSurfaceDesc desc;
+    desc.fFlags = kRenderTarget_GrSurfaceFlag,
+    desc.fWidth = bounds.width();
+    desc.fHeight = bounds.height();
+    desc.fConfig = kRGBA_8888_GrPixelConfig;
+
+    SkAutoTUnref<GrTexture> dst(
+        context->refScratchTexture(desc, GrContext::kApprox_ScratchTexMatch));
+    if (!dst) {
+        return false;
+    }
+
+    // setup new clip
+    GrClip clip(dstRect);
+
+    offset->fX = bounds.left();
+    offset->fY = bounds.top();
+    SkMatrix matrix(ctx.ctm());
+    matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
+    bounds.offset(-srcOffset);
+    SkRect topLeft = SkRect::MakeXYWH(0, 0, 1, 1);
+    SkRect top = SkRect::MakeXYWH(1, 0, dstRect.width() - 2, 1);
+    SkRect topRight = SkRect::MakeXYWH(dstRect.width() - 1, 0, 1, 1);
+    SkRect left = SkRect::MakeXYWH(0, 1, 1, dstRect.height() - 2);
+    SkRect interior = dstRect.makeInset(1, 1);
+    SkRect right = SkRect::MakeXYWH(dstRect.width() - 1, 1, 1, dstRect.height() - 2);
+    SkRect bottomLeft = SkRect::MakeXYWH(0, dstRect.height() - 1, 1, 1);
+    SkRect bottom = SkRect::MakeXYWH(1, dstRect.height() - 1, dstRect.width() - 2, 1);
+    SkRect bottomRight = SkRect::MakeXYWH(dstRect.width() - 1, dstRect.height() - 1, 1, 1);
+    this->drawRect(context, srcTexture, dst, matrix, clip, topLeft, kTopLeft_BoundaryMode, bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, top, kTop_BoundaryMode, bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, topRight, kTopRight_BoundaryMode,
+                   bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, left, kLeft_BoundaryMode, bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, interior, kInterior_BoundaryMode,
+                   bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, right, kRight_BoundaryMode, bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, bottomLeft, kBottomLeft_BoundaryMode,
+                   bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, bottom, kBottom_BoundaryMode, bounds);
+    this->drawRect(context, srcTexture, dst, matrix, clip, bottomRight, kBottomRight_BoundaryMode,
+                   bounds);
+    WrapTexture(dst, bounds.width(), bounds.height(), result);
+    return true;
+}
+#endif
+
+class SkDiffuseLightingImageFilter : public SkLightingImageFilterInternal {
 public:
     static SkImageFilter* Create(SkLight* light, SkScalar surfaceScale, SkScalar kd, SkImageFilter*,
                                  const CropRect*);
@@ -290,20 +419,20 @@ protected:
     SkDiffuseLightingImageFilter(SkLight* light, SkScalar surfaceScale,
                                  SkScalar kd, SkImageFilter* input, const CropRect* cropRect);
     void flatten(SkWriteBuffer& buffer) const override;
-    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
-                               SkBitmap* result, SkIPoint* offset) const override;
+    bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
+                       SkBitmap* result, SkIPoint* offset) const override;
 #if SK_SUPPORT_GPU
-    virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
-                                     const SkIRect& bounds) const override;
+    GrFragmentProcessor* getFragmentProcessor(GrTexture*, const SkMatrix&,
+                                              const SkIRect& bounds, BoundaryMode) const override;
 #endif
 
 private:
     friend class SkLightingImageFilter;
-    typedef SkLightingImageFilter INHERITED;
+    typedef SkLightingImageFilterInternal INHERITED;
     SkScalar fKD;
 };
 
-class SkSpecularLightingImageFilter : public SkLightingImageFilter {
+class SkSpecularLightingImageFilter : public SkLightingImageFilterInternal {
 public:
     static SkImageFilter* Create(SkLight* light, SkScalar surfaceScale,
                                  SkScalar ks, SkScalar shininess, SkImageFilter*, const CropRect*);
@@ -318,30 +447,32 @@ protected:
     SkSpecularLightingImageFilter(SkLight* light, SkScalar surfaceScale, SkScalar ks,
                                   SkScalar shininess, SkImageFilter* input, const CropRect*);
     void flatten(SkWriteBuffer& buffer) const override;
-    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
-                               SkBitmap* result, SkIPoint* offset) const override;
+    bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
+                       SkBitmap* result, SkIPoint* offset) const override;
 #if SK_SUPPORT_GPU
-    virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
-                                     const SkIRect& bounds) const override;
+    GrFragmentProcessor* getFragmentProcessor(GrTexture*, const SkMatrix&,
+                                              const SkIRect& bounds, BoundaryMode) const override;
 #endif
 
 private:
     SkScalar fKS;
     SkScalar fShininess;
     friend class SkLightingImageFilter;
-    typedef SkLightingImageFilter INHERITED;
+    typedef SkLightingImageFilterInternal INHERITED;
 };
 
 #if SK_SUPPORT_GPU
 
 class GrLightingEffect : public GrSingleTextureEffect {
 public:
-    GrLightingEffect(GrTexture* texture, const SkLight* light, SkScalar surfaceScale, const SkMatrix& matrix);
+    GrLightingEffect(GrTexture* texture, const SkLight* light, SkScalar surfaceScale,
+                     const SkMatrix& matrix, BoundaryMode boundaryMode);
     virtual ~GrLightingEffect();
 
     const SkLight* light() const { return fLight; }
     SkScalar surfaceScale() const { return fSurfaceScale; }
     const SkMatrix& filterMatrix() const { return fFilterMatrix; }
+    BoundaryMode boundaryMode() const { return fBoundaryMode; }
 
 protected:
     bool onIsEqual(const GrFragmentProcessor&) const override;
@@ -356,6 +487,7 @@ private:
     const SkLight* fLight;
     SkScalar fSurfaceScale;
     SkMatrix fFilterMatrix;
+    BoundaryMode fBoundaryMode;
 };
 
 class GrDiffuseLightingEffect : public GrLightingEffect {
@@ -364,12 +496,14 @@ public:
                                        const SkLight* light,
                                        SkScalar surfaceScale,
                                        const SkMatrix& matrix,
-                                       SkScalar kd) {
+                                       SkScalar kd,
+                                       BoundaryMode boundaryMode) {
         return SkNEW_ARGS(GrDiffuseLightingEffect, (texture,
                                                     light,
                                                     surfaceScale,
                                                     matrix,
-                                                    kd));
+                                                    kd,
+                                                    boundaryMode));
     }
 
     const char* name() const override { return "DiffuseLighting"; }
@@ -387,7 +521,8 @@ private:
                             const SkLight* light,
                             SkScalar surfaceScale,
                             const SkMatrix& matrix,
-                            SkScalar kd);
+                            SkScalar kd,
+                            BoundaryMode boundaryMode);
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
     typedef GrLightingEffect INHERITED;
@@ -401,13 +536,15 @@ public:
                                        SkScalar surfaceScale,
                                        const SkMatrix& matrix,
                                        SkScalar ks,
-                                       SkScalar shininess) {
+                                       SkScalar shininess,
+                                       BoundaryMode boundaryMode) {
         return SkNEW_ARGS(GrSpecularLightingEffect, (texture,
                                                      light,
                                                      surfaceScale,
                                                      matrix,
                                                      ks,
-                                                     shininess));
+                                                     shininess,
+                                                     boundaryMode));
     }
 
     const char* name() const override { return "SpecularLighting"; }
@@ -427,7 +564,8 @@ private:
                              SkScalar surfaceScale,
                              const SkMatrix& matrix,
                              SkScalar ks,
-                             SkScalar shininess);
+                             SkScalar shininess,
+                             BoundaryMode boundaryMode);
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
     typedef GrLightingEffect INHERITED;
@@ -481,8 +619,7 @@ private:
 class GrGLDistantLight : public GrGLLight {
 public:
     virtual ~GrGLDistantLight() {}
-    virtual void setData(const GrGLProgramDataManager&,
-                         const SkLight* light) const override;
+    void setData(const GrGLProgramDataManager&, const SkLight* light) const override;
     void emitSurfaceToLight(GrGLFPBuilder*, const char* z) override;
 
 private:
@@ -495,8 +632,7 @@ private:
 class GrGLPointLight : public GrGLLight {
 public:
     virtual ~GrGLPointLight() {}
-    virtual void setData(const GrGLProgramDataManager&,
-                         const SkLight* light) const override;
+    void setData(const GrGLProgramDataManager&, const SkLight* light) const override;
     void emitSurfaceToLight(GrGLFPBuilder*, const char* z) override;
 
 private:
@@ -509,8 +645,7 @@ private:
 class GrGLSpotLight : public GrGLLight {
 public:
     virtual ~GrGLSpotLight() {}
-    virtual void setData(const GrGLProgramDataManager&,
-                         const SkLight* light) const override;
+    void setData(const GrGLProgramDataManager&, const SkLight* light) const override;
     void emitSurfaceToLight(GrGLFPBuilder*, const char* z) override;
     void emitLightColor(GrGLFPBuilder*, const char *surfaceToLight) override;
 
@@ -695,7 +830,11 @@ private:
 
 class SkSpotLight : public SkLight {
 public:
-    SkSpotLight(const SkPoint3& location, const SkPoint3& target, SkScalar specularExponent, SkScalar cutoffAngle, SkColor color)
+    SkSpotLight(const SkPoint3& location,
+                const SkPoint3& target,
+                SkScalar specularExponent,
+                SkScalar cutoffAngle,
+                SkColor color)
      : INHERITED(color),
        fLocation(location),
        fTarget(target),
@@ -723,7 +862,14 @@ public:
         SkPoint3 target(target2.fX, target2.fY, SkScalarAve(targetZ.fX, targetZ.fY));
         SkPoint3 s = target - location;
         s.normalize();
-        return new SkSpotLight(location, target, fSpecularExponent, fCosOuterConeAngle, fCosInnerConeAngle, fConeScale, s, color());
+        return new SkSpotLight(location,
+                               target,
+                               fSpecularExponent,
+                               fCosOuterConeAngle,
+                               fCosInnerConeAngle,
+                               fConeScale,
+                               s,
+                               color());
     }
 
     SkPoint3 surfaceToLight(int x, int y, int z, SkScalar surfaceScale) const {
@@ -777,7 +923,14 @@ public:
                         SkScalarIsFinite(fConeScale));
     }
 protected:
-    SkSpotLight(const SkPoint3& location, const SkPoint3& target, SkScalar specularExponent, SkScalar cosOuterConeAngle, SkScalar cosInnerConeAngle, SkScalar coneScale, const SkPoint3& s, const SkPoint3& color)
+    SkSpotLight(const SkPoint3& location,
+                const SkPoint3& target,
+                SkScalar specularExponent,
+                SkScalar cosOuterConeAngle,
+                SkScalar cosInnerConeAngle,
+                SkScalar coneScale,
+                const SkPoint3& s,
+                const SkPoint3& color)
      : INHERITED(color),
        fLocation(location),
        fTarget(target),
@@ -960,8 +1113,12 @@ SkImageFilter* SkDiffuseLightingImageFilter::Create(SkLight* light, SkScalar sur
     return SkNEW_ARGS(SkDiffuseLightingImageFilter, (light, surfaceScale, kd, input, cropRect));
 }
 
-SkDiffuseLightingImageFilter::SkDiffuseLightingImageFilter(SkLight* light, SkScalar surfaceScale, SkScalar kd, SkImageFilter* input, const CropRect* cropRect)
-  : SkLightingImageFilter(light, surfaceScale, input, cropRect),
+SkDiffuseLightingImageFilter::SkDiffuseLightingImageFilter(SkLight* light,
+                                                           SkScalar surfaceScale,
+                                                           SkScalar kd,
+                                                           SkImageFilter* input,
+                                                           const CropRect* cropRect)
+  : INHERITED(light, surfaceScale, input, cropRect),
     fKD(kd)
 {
 }
@@ -1020,13 +1177,28 @@ bool SkDiffuseLightingImageFilter::onFilterImage(Proxy* proxy,
     bounds.offset(-srcOffset);
     switch (transformedLight->type()) {
         case SkLight::kDistant_LightType:
-            lightBitmap<DiffuseLightingType, SkDistantLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<DiffuseLightingType, SkDistantLight>(lightingType,
+                                                             transformedLight,
+                                                             src,
+                                                             dst,
+                                                             surfaceScale(),
+                                                             bounds);
             break;
         case SkLight::kPoint_LightType:
-            lightBitmap<DiffuseLightingType, SkPointLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<DiffuseLightingType, SkPointLight>(lightingType,
+                                                           transformedLight,
+                                                           src,
+                                                           dst,
+                                                           surfaceScale(),
+                                                           bounds);
             break;
         case SkLight::kSpot_LightType:
-            lightBitmap<DiffuseLightingType, SkSpotLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<DiffuseLightingType, SkSpotLight>(lightingType,
+                                                          transformedLight,
+                                                          src,
+                                                          dst,
+                                                          surfaceScale(),
+                                                          bounds);
             break;
     }
 
@@ -1042,15 +1214,14 @@ void SkDiffuseLightingImageFilter::toString(SkString* str) const {
 #endif
 
 #if SK_SUPPORT_GPU
-bool SkDiffuseLightingImageFilter::asFragmentProcessor(GrFragmentProcessor** fp,
+GrFragmentProcessor* SkDiffuseLightingImageFilter::getFragmentProcessor(
                                                        GrTexture* texture,
                                                        const SkMatrix& matrix,
-                                                       const SkIRect&) const {
-    if (fp) {
-        SkScalar scale = SkScalarMul(surfaceScale(), SkIntToScalar(255));
-        *fp = GrDiffuseLightingEffect::Create(texture, light(), scale, matrix, kd());
-    }
-    return true;
+                                                       const SkIRect&,
+                                                       BoundaryMode boundaryMode
+) const {
+    SkScalar scale = SkScalarMul(surfaceScale(), SkIntToScalar(255));
+    return GrDiffuseLightingEffect::Create(texture, light(), scale, matrix, kd(), boundaryMode);
 }
 #endif
 
@@ -1073,8 +1244,13 @@ SkImageFilter* SkSpecularLightingImageFilter::Create(SkLight* light, SkScalar su
                       (light, surfaceScale, ks, shininess, input, cropRect));
 }
 
-SkSpecularLightingImageFilter::SkSpecularLightingImageFilter(SkLight* light, SkScalar surfaceScale, SkScalar ks, SkScalar shininess, SkImageFilter* input, const CropRect* cropRect)
-  : SkLightingImageFilter(light, surfaceScale, input, cropRect),
+SkSpecularLightingImageFilter::SkSpecularLightingImageFilter(SkLight* light,
+                                                             SkScalar surfaceScale,
+                                                             SkScalar ks,
+                                                             SkScalar shininess,
+                                                             SkImageFilter* input,
+                                                             const CropRect* cropRect)
+  : INHERITED(light, surfaceScale, input, cropRect),
     fKS(ks),
     fShininess(shininess)
 {
@@ -1136,13 +1312,28 @@ bool SkSpecularLightingImageFilter::onFilterImage(Proxy* proxy,
     SkAutoTUnref<SkLight> transformedLight(light()->transform(ctx.ctm()));
     switch (transformedLight->type()) {
         case SkLight::kDistant_LightType:
-            lightBitmap<SpecularLightingType, SkDistantLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<SpecularLightingType, SkDistantLight>(lightingType,
+                                                              transformedLight,
+                                                              src,
+                                                              dst,
+                                                              surfaceScale(),
+                                                              bounds);
             break;
         case SkLight::kPoint_LightType:
-            lightBitmap<SpecularLightingType, SkPointLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<SpecularLightingType, SkPointLight>(lightingType,
+                                                            transformedLight,
+                                                            src,
+                                                            dst,
+                                                            surfaceScale(),
+                                                            bounds);
             break;
         case SkLight::kSpot_LightType:
-            lightBitmap<SpecularLightingType, SkSpotLight>(lightingType, transformedLight, src, dst, surfaceScale(), bounds);
+            lightBitmap<SpecularLightingType, SkSpotLight>(lightingType,
+                                                           transformedLight,
+                                                           src,
+                                                           dst,
+                                                           surfaceScale(),
+                                                           bounds);
             break;
     }
     return true;
@@ -1157,15 +1348,14 @@ void SkSpecularLightingImageFilter::toString(SkString* str) const {
 #endif
 
 #if SK_SUPPORT_GPU
-bool SkSpecularLightingImageFilter::asFragmentProcessor(GrFragmentProcessor** fp,
-                                                        GrTexture* texture,
-                                                        const SkMatrix& matrix,
-                                                        const SkIRect&) const {
-    if (fp) {
-        SkScalar scale = SkScalarMul(surfaceScale(), SkIntToScalar(255));
-        *fp = GrSpecularLightingEffect::Create(texture, light(), scale, matrix, ks(), shininess());
-    }
-    return true;
+GrFragmentProcessor* SkSpecularLightingImageFilter::getFragmentProcessor(
+                                                         GrTexture* texture,
+                                                         const SkMatrix& matrix,
+                                                         const SkIRect&,
+                                                         BoundaryMode boundaryMode) const {
+    SkScalar scale = SkScalarMul(surfaceScale(), SkIntToScalar(255));
+    return GrSpecularLightingEffect::Create(texture, light(), scale, matrix, ks(), shininess(),
+                                            boundaryMode);
 }
 #endif
 
@@ -1202,6 +1392,81 @@ SkLight* create_random_light(SkRandom* random) {
     }
 }
 
+SkString emitNormalFunc(BoundaryMode mode,
+                        const char* pointToNormalName,
+                        const char* sobelFuncName) {
+    SkString result;
+    switch (mode) {
+    case kTopLeft_BoundaryMode:
+        result.printf("\treturn %s(%s(0.0, 0.0, m[4], m[5], m[7], m[8], %g),\n"
+                      "\t          %s(0.0, 0.0, m[4], m[7], m[5], m[8], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gTwoThirds,
+                                         sobelFuncName, gTwoThirds);
+        break;
+    case kTop_BoundaryMode:
+        result.printf("\treturn %s(%s(0.0, 0.0, m[3], m[5], m[6], m[8], %g),\n"
+                      "\t          %s(0.0, 0.0, m[4], m[7], m[5], m[8], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gOneThird,
+                                         sobelFuncName, gOneHalf);
+        break;
+    case kTopRight_BoundaryMode:
+        result.printf("\treturn %s(%s( 0.0,  0.0, m[3], m[4], m[6], m[7], %g),\n"
+                      "\t          %s(m[3], m[6], m[4], m[7],  0.0,  0.0, %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gTwoThirds,
+                                         sobelFuncName, gTwoThirds);
+        break;
+    case kLeft_BoundaryMode:
+        result.printf("\treturn %s(%s(m[1], m[2], m[4], m[5], m[7], m[8], %g),\n"
+                      "\t          %s( 0.0,  0.0, m[1], m[7], m[2], m[8], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gOneHalf,
+                                         sobelFuncName, gOneThird);
+        break;
+    case kInterior_BoundaryMode:
+        result.printf("\treturn %s(%s(m[0], m[2], m[3], m[5], m[6], m[8], %g),\n"
+                      "\t          %s(m[0], m[6], m[1], m[7], m[2], m[8], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gOneQuarter,
+                                         sobelFuncName, gOneQuarter);
+        break;
+    case kRight_BoundaryMode:
+        result.printf("\treturn %s(%s(m[0], m[1], m[3], m[4], m[6], m[7], %g),\n"
+                      "\t          %s(m[0], m[6], m[1], m[7],  0.0,  0.0, %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gOneHalf,
+                                         sobelFuncName, gOneThird);
+        break;
+    case kBottomLeft_BoundaryMode:
+        result.printf("\treturn %s(%s(m[1], m[2], m[4], m[5],  0.0,  0.0, %g),\n"
+                      "\t          %s( 0.0,  0.0, m[1], m[4], m[2], m[5], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gTwoThirds,
+                                         sobelFuncName, gTwoThirds);
+        break;
+    case kBottom_BoundaryMode:
+        result.printf("\treturn %s(%s(m[0], m[2], m[3], m[5],  0.0,  0.0, %g),\n"
+                      "\t          %s(m[0], m[3], m[1], m[4], m[2], m[5], %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gOneThird,
+                                         sobelFuncName, gOneHalf);
+        break;
+    case kBottomRight_BoundaryMode:
+        result.printf("\treturn %s(%s(m[0], m[1], m[3], m[4],  0.0,  0.0, %g),\n"
+                      "\t          %s(m[0], m[3], m[1], m[4],  0.0,  0.0, %g),\n"
+                      "\t          surfaceScale);\n",
+                      pointToNormalName, sobelFuncName, gTwoThirds,
+                                         sobelFuncName, gTwoThirds);
+        break;
+    default:
+        SkASSERT(false);
+        break;
+    }
+    return result;
+}
+
 }
 
 class GrGLLightingEffect  : public GrGLFragmentProcessor {
@@ -1209,12 +1474,12 @@ public:
     GrGLLightingEffect(const GrProcessor&);
     virtual ~GrGLLightingEffect();
 
-    virtual void emitCode(GrGLFPBuilder*,
-                          const GrFragmentProcessor&,
-                          const char* outputColor,
-                          const char* inputColor,
-                          const TransformedCoordsArray&,
-                          const TextureSamplerArray&) override;
+    void emitCode(GrGLFPBuilder*,
+                  const GrFragmentProcessor&,
+                  const char* outputColor,
+                  const char* inputColor,
+                  const TransformedCoordsArray&,
+                  const TextureSamplerArray&) override;
 
     static inline void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder* b);
 
@@ -1232,6 +1497,7 @@ private:
     UniformHandle       fImageIncrementUni;
     UniformHandle       fSurfaceScaleUni;
     GrGLLight*          fLight;
+    BoundaryMode        fBoundaryMode;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1268,11 +1534,13 @@ private:
 GrLightingEffect::GrLightingEffect(GrTexture* texture,
                                    const SkLight* light,
                                    SkScalar surfaceScale,
-                                   const SkMatrix& matrix)
+                                   const SkMatrix& matrix,
+                                   BoundaryMode boundaryMode)
     : INHERITED(texture, GrCoordTransform::MakeDivByTextureWHMatrix(texture))
     , fLight(light)
     , fSurfaceScale(surfaceScale)
-    , fFilterMatrix(matrix) {
+    , fFilterMatrix(matrix)
+    , fBoundaryMode(boundaryMode) {
     fLight->ref();
     if (light->requiresFragmentPosition()) {
         this->setWillReadFragmentPosition();
@@ -1286,7 +1554,8 @@ GrLightingEffect::~GrLightingEffect() {
 bool GrLightingEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
     const GrLightingEffect& s = sBase.cast<GrLightingEffect>();
     return fLight->isEqual(*s.fLight) &&
-           fSurfaceScale == s.fSurfaceScale;
+           fSurfaceScale == s.fSurfaceScale &&
+           fBoundaryMode == s.fBoundaryMode;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1295,8 +1564,9 @@ GrDiffuseLightingEffect::GrDiffuseLightingEffect(GrTexture* texture,
                                                  const SkLight* light,
                                                  SkScalar surfaceScale,
                                                  const SkMatrix& matrix,
-                                                 SkScalar kd)
-    : INHERITED(texture, light, surfaceScale, matrix), fKD(kd) {
+                                                 SkScalar kd,
+                                                 BoundaryMode boundaryMode)
+    : INHERITED(texture, light, surfaceScale, matrix, boundaryMode), fKD(kd) {
     this->initClassID<GrDiffuseLightingEffect>();
 }
 
@@ -1328,8 +1598,9 @@ GrFragmentProcessor* GrDiffuseLightingEffect::TestCreate(SkRandom* random,
     for (int i = 0; i < 9; i++) {
         matrix[i] = random->nextUScalar1();
     }
+    BoundaryMode mode = static_cast<BoundaryMode>(random->nextU() % kBoundaryModeCount);
     return GrDiffuseLightingEffect::Create(textures[GrProcessorUnitTest::kAlphaTextureIdx],
-                                           light, surfaceScale, matrix, kd);
+                                           light, surfaceScale, matrix, kd, mode);
 }
 
 
@@ -1338,6 +1609,7 @@ GrFragmentProcessor* GrDiffuseLightingEffect::TestCreate(SkRandom* random,
 GrGLLightingEffect::GrGLLightingEffect(const GrProcessor& fp) {
     const GrLightingEffect& m = fp.cast<GrLightingEffect>();
     fLight = m.light()->createGLLight();
+    fBoundaryMode = m.boundaryMode();
 }
 
 GrGLLightingEffect::~GrGLLightingEffect() {
@@ -1388,27 +1660,23 @@ void GrGLLightingEffect::emitCode(GrGLFPBuilder* builder,
                             "pointToNormal",
                             SK_ARRAY_COUNT(gPointToNormalArgs),
                             gPointToNormalArgs,
-                            "\treturn normalize(vec3(-x * scale, y * scale, 1));\n",
+                            "\treturn normalize(vec3(-x * scale, -y * scale, 1));\n",
                             &pointToNormalName);
 
     static const GrGLShaderVar gInteriorNormalArgs[] =  {
         GrGLShaderVar("m", kFloat_GrSLType, 9),
         GrGLShaderVar("surfaceScale", kFloat_GrSLType),
     };
-    SkString interiorNormalBody;
-    interiorNormalBody.appendf("\treturn %s(%s(m[0], m[2], m[3], m[5], m[6], m[8], 0.25),\n"
-                               "\t       %s(m[0], m[6], m[1], m[7], m[2], m[8], 0.25),\n"
-                               "\t       surfaceScale);\n",
-                                pointToNormalName.c_str(),
-                                sobelFuncName.c_str(),
-                                sobelFuncName.c_str());
-    SkString interiorNormalName;
+    SkString normalBody = emitNormalFunc(fBoundaryMode,
+                                         pointToNormalName.c_str(),
+                                         sobelFuncName.c_str());
+    SkString normalName;
     fsBuilder->emitFunction(kVec3f_GrSLType,
-                            "interiorNormal",
+                            "normal",
                             SK_ARRAY_COUNT(gInteriorNormalArgs),
                             gInteriorNormalArgs,
-                            interiorNormalBody.c_str(),
-                            &interiorNormalName);
+                            normalBody.c_str(),
+                            &normalName);
 
     fsBuilder->codeAppendf("\t\tvec2 coord = %s;\n", coords2D.c_str());
     fsBuilder->codeAppend("\t\tfloat m[9];\n");
@@ -1417,7 +1685,7 @@ void GrGLLightingEffect::emitCode(GrGLFPBuilder* builder,
     const char* surfScale = builder->getUniformCStr(fSurfaceScaleUni);
 
     int index = 0;
-    for (int dy = -1; dy <= 1; dy++) {
+    for (int dy = 1; dy >= -1; dy--) {
         for (int dx = -1; dx <= 1; dx++) {
             SkString texCoords;
             texCoords.appendf("coord + vec2(%d, %d) * %s", dx, dy, imgInc);
@@ -1432,7 +1700,7 @@ void GrGLLightingEffect::emitCode(GrGLFPBuilder* builder,
     fLight->emitSurfaceToLight(builder, arg.c_str());
     fsBuilder->codeAppend(";\n");
     fsBuilder->codeAppendf("\t\t%s = %s(%s(m, %s), surfaceToLight, ",
-                           outputColor, lightFunc.c_str(), interiorNormalName.c_str(), surfScale);
+                           outputColor, lightFunc.c_str(), normalName.c_str(), surfScale);
     fLight->emitLightColor(builder, "surfaceToLight");
     fsBuilder->codeAppend(");\n");
     SkString modulate;
@@ -1442,7 +1710,8 @@ void GrGLLightingEffect::emitCode(GrGLFPBuilder* builder,
 
 void GrGLLightingEffect::GenKey(const GrProcessor& proc,
                                 const GrGLCaps& caps, GrProcessorKeyBuilder* b) {
-    b->add32(proc.cast<GrLightingEffect>().light()->type());
+    const GrLightingEffect& lighting = proc.cast<GrLightingEffect>();
+    b->add32(lighting.boundaryMode() << 2 | lighting.light()->type());
 }
 
 void GrGLLightingEffect::setData(const GrGLProgramDataManager& pdman,
@@ -1500,8 +1769,9 @@ GrSpecularLightingEffect::GrSpecularLightingEffect(GrTexture* texture,
                                                    SkScalar surfaceScale,
                                                    const SkMatrix& matrix,
                                                    SkScalar ks,
-                                                   SkScalar shininess)
-    : INHERITED(texture, light, surfaceScale, matrix),
+                                                   SkScalar shininess,
+                                                   BoundaryMode boundaryMode)
+    : INHERITED(texture, light, surfaceScale, matrix, boundaryMode),
       fKS(ks),
       fShininess(shininess) {
     this->initClassID<GrSpecularLightingEffect>();
@@ -1537,8 +1807,9 @@ GrFragmentProcessor* GrSpecularLightingEffect::TestCreate(SkRandom* random,
     for (int i = 0; i < 9; i++) {
         matrix[i] = random->nextUScalar1();
     }
+    BoundaryMode mode = static_cast<BoundaryMode>(random->nextU() % kBoundaryModeCount);
     return GrSpecularLightingEffect::Create(textures[GrProcessorUnitTest::kAlphaTextureIdx],
-                                            light, surfaceScale, matrix, ks, shininess);
+                                            light, surfaceScale, matrix, ks, shininess, mode);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1554,7 +1825,10 @@ void GrGLSpecularLightingEffect::emitLightFunc(GrGLFPBuilder* builder, SkString*
     fKSUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                  kFloat_GrSLType, kDefault_GrSLPrecision, "KS", &ks);
     fShininessUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
-                                        kFloat_GrSLType, kDefault_GrSLPrecision, "Shininess", &shininess);
+                                        kFloat_GrSLType,
+                                        kDefault_GrSLPrecision,
+                                        "Shininess",
+                                        &shininess);
 
     static const GrGLShaderVar gLightArgs[] = {
         GrGLShaderVar("normal", kVec3f_GrSLType),
diff --git a/src/effects/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index 622713d796..6d2ee01d52 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -25,6 +25,7 @@ class GrMagnifierEffect : public GrSingleTextureEffect {
 
 public:
     static GrFragmentProcessor* Create(GrTexture* texture,
+                                       const SkRect& bounds,
                                        float xOffset,
                                        float yOffset,
                                        float xInvZoom,
@@ -32,6 +33,7 @@ public:
                                        float xInvInset,
                                        float yInvInset) {
         return SkNEW_ARGS(GrMagnifierEffect, (texture,
+                                              bounds,
                                               xOffset,
                                               yOffset,
                                               xInvZoom,
@@ -48,15 +50,22 @@ public:
 
     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,
@@ -64,6 +73,7 @@ private:
                       float xInvInset,
                       float yInvInset)
         : GrSingleTextureEffect(texture, GrCoordTransform::MakeDivByTextureWHMatrix(texture))
+        , fBounds(bounds)
         , fXOffset(xOffset)
         , fYOffset(yOffset)
         , fXInvZoom(xInvZoom)
@@ -79,6 +89,7 @@ private:
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
 
+    SkRect fBounds;
     float fXOffset;
     float fYOffset;
     float fXInvZoom;
@@ -109,6 +120,7 @@ private:
     UniformHandle       fOffsetVar;
     UniformHandle       fInvZoomVar;
     UniformHandle       fInvInsetVar;
+    UniformHandle       fBoundsVar;
 
     typedef GrGLFragmentProcessor INHERITED;
 };
@@ -134,6 +146,10 @@ void GrGLMagnifierEffect::emitCode(GrGLFPBuilder* builder,
         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);
@@ -142,9 +158,9 @@ void GrGLMagnifierEffect::emitCode(GrGLFPBuilder* builder,
                            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");
@@ -175,6 +191,8 @@ void GrGLMagnifierEffect::setData(const GrGLProgramDataManager& pdman,
     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());
 }
 
 /////////////////////////////////////////////////////////////////////
@@ -206,6 +224,7 @@ GrFragmentProcessor* GrMagnifierEffect::TestCreate(SkRandom* random,
 
     GrFragmentProcessor* effect = GrMagnifierEffect::Create(
         texture,
+        SkRect::MakeWH(SkIntToScalar(kMaxWidth), SkIntToScalar(kMaxHeight)),
         (float) width / texture->width(),
         (float) height / texture->height(),
         texture->width() / (float) x,
@@ -220,7 +239,8 @@ GrFragmentProcessor* GrMagnifierEffect::TestCreate(SkRandom* random,
 
 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 &&
@@ -258,18 +278,27 @@ SkMagnifierImageFilter::SkMagnifierImageFilter(const SkRect& srcRect, SkScalar i
 
 #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;
 }