First draft of non-scale/translate filters plus blit optimization.

src/core/SkCanvas.cpp

Index: src/core/SkCanvas.cpp
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 11dc739f4c4dc6aa0509f8ba404a56fa246817e4..f9eb0ebbfef45e2823a9bb91443fa18b60fcd5e3 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -113,11 +113,16 @@ struct DeviceCM {
     SkRasterClip        fClip;
     const SkMatrix*     fMatrix;
     SkPaint*            fPaint; // may be null (in the future)
+    SkMatrix            fStashedMatrix;
+    SkMatrix            fExtraMatrix;
 
     DeviceCM(SkBaseDevice* device, const SkPaint* paint, SkCanvas* canvas,
-             bool conservativeRasterClip)
+             bool conservativeRasterClip, const SkMatrix& stashedMatrix,
+             const SkMatrix& extraMatrix)
         : fNext(NULL)
         , fClip(conservativeRasterClip)
+        , fStashedMatrix(stashedMatrix)
+        , fExtraMatrix(extraMatrix)
     {
         if (NULL != device) {
             device->ref();
@@ -438,7 +443,7 @@ SkBaseDevice* SkCanvas::init(SkBaseDevice* device, InitFlags flags) {
     fMCRec = (MCRec*)fMCStack.push_back();
     new (fMCRec) MCRec(fConservativeRasterClip);
 
-    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, NULL, NULL, fConservativeRasterClip));
+    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, NULL, NULL, fConservativeRasterClip, fMCRec->fMatrix, SkMatrix::I()));
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
@@ -831,7 +836,8 @@ static bool bounds_affects_clip(SkCanvas::SaveFlags flags) {
 }
 
 bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
-                              SkIRect* intersection, const SkImageFilter* imageFilter) {
+                              SkIRect* intersection, const SkImageFilter* imageFilter,
+                              const SkMatrix* shearAndRotateMatrix) {
     SkIRect clipBounds;
     if (!this->getClipDeviceBounds(&clipBounds)) {
         return false;
@@ -840,8 +846,24 @@ bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
     const SkMatrix& ctm = fMCRec->fMatrix;  // this->getTotalMatrix()
 
     if (imageFilter) {
+        if (shearAndRotateMatrix) {
+            SkMatrix shearAndRotateInverse;
+            if (!shearAndRotateMatrix->invert(&shearAndRotateInverse)) {
+                return false;
+            }
+            SkMatrix matrix;
+            if (!ctm.invert(&matrix)) {
+                return false;
+            }
+            matrix.postConcat(shearAndRotateInverse);
+            matrix.postConcat(ctm);
+            SkRect floatBounds;
+            matrix.mapRect(&floatBounds, SkRect::Make(clipBounds));
+            clipBounds = floatBounds.roundOut();
+        }
         imageFilter->filterBounds(clipBounds, ctm, &clipBounds);
     }
+
     SkIRect ir;
     if (bounds) {
         SkRect r;
@@ -899,6 +921,23 @@ void SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, Sav
 #ifndef SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG
     flags |= kClipToLayer_SaveFlag;
 #endif
+    SkImageFilter* imageFilter = paint ? paint->getImageFilter() : NULL;
+    SkMatrix matrix = fMCRec->fMatrix;
+    SkMatrix shearAndRotate = SkMatrix::I();
+    bool doShearAndRotate = false;
+    if (imageFilter && !matrix.isScaleTranslate()) {
+        doShearAndRotate = true;
+        SkMatrix scaleAndTranslate;
+        scaleAndTranslate.setTranslate(matrix.getTranslateX(), matrix.getTranslateY());
+        SkScalar xScale = SkScalarSqrt(matrix[0] * matrix[0] + matrix[3] * matrix[3]);
+        SkScalar yScale = SkScalarSqrt(matrix[1] * matrix[1] + matrix[4] * matrix[4]);
+        scaleAndTranslate.postScale(xScale, yScale);
+        if (!scaleAndTranslate.invert(&shearAndRotate)) {
+            SkASSERT(false);
+        }
+        shearAndRotate.preConcat(matrix);
+        fMCRec->fMatrix = scaleAndTranslate;
+    }
 
     // do this before we create the layer. We don't call the public save() since
     // that would invoke a possibly overridden virtual
@@ -907,7 +946,7 @@ 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, doShearAndRotate ? &shearAndRotate : NULL)) {
         return;
     }
 
@@ -951,7 +990,7 @@ 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, shearAndRotate));
     device->unref();
 
     layer->fNext = fMCRec->fTopLayer;
@@ -1000,10 +1039,13 @@ void SkCanvas::internalRestore() {
         if (layer->fNext) {
             const SkIPoint& origin = layer->fDevice->getOrigin();
             this->internalDrawDevice(layer->fDevice, origin.x(), origin.y(),
-                                     layer->fPaint);
+                                     layer->fPaint, layer->fExtraMatrix);
             // reset this, since internalDrawDevice will have set it to true
             fDeviceCMDirty = true;
         }
+        if (layer->fPaint && layer->fPaint->fImageFilter) {
+            fMCRec->fMatrix = layer->fStashedMatrix;
+        }
         SkDELETE(layer);
     }
 }
@@ -1108,7 +1150,7 @@ void SkCanvas::internalDrawBitmap(const SkBitmap& bitmap,
 }
 
 void SkCanvas::internalDrawDevice(SkBaseDevice* srcDev, int x, int y,
-                                  const SkPaint* paint) {
+                                  const SkPaint* paint, const SkMatrix& extraMatrix) {
     SkPaint tmp;
     if (NULL == paint) {
         paint = &tmp;
@@ -1133,8 +1175,16 @@ void SkCanvas::internalDrawDevice(SkBaseDevice* srcDev, int x, int y,
             if (filter->filterImage(&proxy, src, ctx, &dst, &offset)) {
                 SkPaint tmpUnfiltered(*paint);
                 tmpUnfiltered.setImageFilter(NULL);
-                dstDev->drawSprite(iter, dst, pos.x() + offset.x(), pos.y() + offset.y(),
-                                   tmpUnfiltered);
+                if (extraMatrix.isIdentity()) {
+                    offset += pos;
+                    dstDev->drawSprite(iter, dst, offset.x(), offset.y(),
+                                       tmpUnfiltered);
+                } else {
+                    SkMatrix matrix = extraMatrix;
+                    matrix.preTranslate(offset.x(), offset.y());
+                    dstDev->drawBitmap(iter, dst, matrix,
+                                       tmpUnfiltered);
+                }
             }
         } else {
             dstDev->drawDevice(iter, srcDev, pos.x(), pos.y(), *paint);