Implement support for non-scale/translate CTM in image filters.

src/core/SkCanvas.cpp

Index: src/core/SkCanvas.cpp
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 11dc739f4c4dc6aa0509f8ba404a56fa246817e4..8babd29ba444fb3ffa94e73492d8d61ff4f35f8b 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -113,11 +113,13 @@ struct DeviceCM {
     SkRasterClip        fClip;
     const SkMatrix*     fMatrix;
     SkPaint*            fPaint; // may be null (in the future)

[robertphillips, 2015/03/20 14:01:10]

// The stashed matrix is used for ... ?

+    SkMatrix            fStashedMatrix;
 
     DeviceCM(SkBaseDevice* device, const SkPaint* paint, SkCanvas* canvas,
-             bool conservativeRasterClip)
+             bool conservativeRasterClip, const SkMatrix& stashedMatrix)
         : fNext(NULL)
         , fClip(conservativeRasterClip)
+        , fStashedMatrix(stashedMatrix)
     {
         if (NULL != device) {
             device->ref();
@@ -438,7 +440,7 @@ SkBaseDevice* SkCanvas::init(SkBaseDevice* device, InitFlags flags) {
     fMCRec = (MCRec*)fMCStack.push_back();
     new (fMCRec) MCRec(fConservativeRasterClip);
 

[robertphillips, 2015/03/20 14:01:09]

overlength ?

[Stephen White, 2015/03/20 14:47:21]

Done.

-    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, NULL, NULL, fConservativeRasterClip));
+    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, NULL, NULL, fConservativeRasterClip, fMCRec->fMatrix));
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
@@ -899,6 +901,20 @@ void SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, Sav
 #ifndef SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG
     flags |= kClipToLayer_SaveFlag;
 #endif
+    SkLazyPaint lazyP;
+    SkImageFilter* imageFilter = paint ? paint->getImageFilter() : NULL;

[robertphillips, 2015/03/20 14:01:09]

Can matrix be a "const&" rather than a copy ?

[Stephen White, 2015/03/20 14:47:21]

No. fMCRec->fMatrix will be modified by resetMatrix()/scale() below, which will
hose the ref (I think).

+    SkMatrix matrix = fMCRec->fMatrix;
+    SkMatrix remainder;
+    SkSize scale;
+    if (imageFilter && !matrix.isScaleTranslate() && matrix.decomposeScale(&scale, &remainder)) {
+        this->resetMatrix();
+        this->scale(scale.width(), scale.height());
+        SkAutoTUnref<SkImageFilter> matrixFilter(SkImageFilter::CreateMatrixFilter(remainder, SkFilterQuality::kHigh_SkFilterQuality, imageFilter));
+        imageFilter = matrixFilter.get();
+        SkPaint* p = lazyP.set(*paint);
+        p->setImageFilter(imageFilter);
+        paint = p;
+    }
 
     // do this before we create the layer. We don't call the public save() since
     // that would invoke a possibly overridden virtual
@@ -907,7 +923,7 @@ void SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, Sav
     fDeviceCMDirty = true;
 
     SkIRect ir;
-    if (!this->clipRectBounds(bounds, flags, &ir, paint ? paint->getImageFilter() : NULL)) {
+    if (!this->clipRectBounds(bounds, flags, &ir, imageFilter)) {
         return;
     }
 
@@ -951,7 +967,7 @@ void SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, Sav
     }
 
     device->setOrigin(ir.fLeft, ir.fTop);
-    DeviceCM* layer = SkNEW_ARGS(DeviceCM, (device, paint, this, fConservativeRasterClip));
+    DeviceCM* layer = SkNEW_ARGS(DeviceCM, (device, paint, this, fConservativeRasterClip, matrix));
     device->unref();
 
     layer->fNext = fMCRec->fTopLayer;
@@ -1004,6 +1020,9 @@ void SkCanvas::internalRestore() {
             // reset this, since internalDrawDevice will have set it to true
             fDeviceCMDirty = true;
         }
+        if (layer->fPaint && layer->fPaint->fImageFilter) {
+            fMCRec->fMatrix = layer->fStashedMatrix;
+        }
         SkDELETE(layer);
     }
 }