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

src/core/SkCanvas.cpp

 /*
  * Copyright 2008 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 "SkCanvas.h"
 #include "SkCanvasPriv.h"
 #include "SkBitmapDevice.h"
@@ skipping 95 matching lines @@
     these are used (assuming we're not on a layer) we rebuild these cache
     values: they reflect the top of the save stack, but translated and clipped
     by the device's XY offset and bitmap-bounds.
 */
 struct DeviceCM {
     DeviceCM*           fNext;
     SkBaseDevice*       fDevice;
     SkRasterClip        fClip;
     const SkMatrix*     fMatrix;
     SkPaint*            fPaint; // may be null (in the future)
+    SkMatrix            fStashedMatrix; // Original CTM; used by imageFilter at saveLayer time
 
     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();
             device->onAttachToCanvas(canvas);
         }
         fDevice = device;
         fPaint = paint ? SkNEW_ARGS(SkPaint, (*paint)) : NULL;
     }
 
     ~DeviceCM() {
@@ skipping 300 matching lines @@
     fCachedLocalClipBoundsDirty = true;
     fAllowSoftClip = true;
     fAllowSimplifyClip = false;
     fDeviceCMDirty = true;
     fSaveCount = 1;
     fMetaData = NULL;
 
     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));
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
 
     fClipStack.reset(SkNEW(SkClipStack));
 
     if (device) {
         device->initForRootLayer(fProps.pixelGeometry());
         if (device->forceConservativeRasterClip()) {
             fConservativeRasterClip = true;
@@ skipping 440 matching lines @@
     fSaveCount += 1;
     this->internalSaveLayer(bounds, paint, flags, strategy);
     return this->getSaveCount() - 1;
 }
 
 void SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, SaveFlags flags,
                                  SaveLayerStrategy strategy) {
 #ifndef SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG
     flags |= kClipToLayer_SaveFlag;
 #endif
+    SkLazyPaint lazyP;
+    SkImageFilter* imageFilter = paint ? paint->getImageFilter() : NULL;
+    SkMatrix matrix = fMCRec->fMatrix;
+    SkMatrix remainder;
+    SkSize scale;
+    if (imageFilter && !matrix.isScaleTranslate() && matrix.decomposeScale(&scale, &remainder)) {
+        this->resetMatrix();

[reed1, 2015/03/26 15:54:03]

these two calls for matrix changes are virtual, which we don't want to make
(esp. if we're in a picture-recorder).

[Stephen White, 2015/03/26 16:18:34]

Hmm -- they don't seem to be virtual on SkCanvas? At any rate, I was messing the
fMCRec->fMatrix directly before, and you asked me to change it. I must've
misunderstood -- what should I change it to?

+        this->scale(scale.width(), scale.height());
+        SkAutoTUnref<SkImageFilter> matrixFilter(SkImageFilter::CreateMatrixFilter(remainder, SkFilterQuality::kHigh_SkFilterQuality, imageFilter));

[reed1, 2015/03/26 15:54:03]

kLow might be more honest, since by definition remainder has rotation/skew which
we always leave to kLow (bilerp).

[Stephen White, 2015/03/26 16:18:34]

Done.

+        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
     this->internalSave();
 
     fDeviceCMDirty = true;
 
     SkIRect ir;
-    if (!this->clipRectBounds(bounds, flags, &ir, paint ? paint->getImageFilter() : NULL)) {
+    if (!this->clipRectBounds(bounds, flags, &ir, imageFilter)) {
         return;
     }
 
     // FIXME: do willSaveLayer() overriders returning kNoLayer_SaveLayerStrategy really care about
     // the clipRectBounds() call above?
     if (kNoLayer_SaveLayerStrategy == strategy) {
         return;
     }
 
     bool isOpaque = !SkToBool(flags & kHasAlphaLayer_SaveFlag);
@@ skipping 24 matching lines @@
     }
 #endif
     device = device->onCreateDevice(SkBaseDevice::CreateInfo(info, usage, geo), paint);
     if (NULL == device) {
         SkErrorInternals::SetError( kInternalError_SkError,
                                     "Unable to create device for layer.");
         return;
     }
 
     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;
     fMCRec->fLayer = layer;
     fMCRec->fTopLayer = layer;    // this field is NOT an owner of layer
 }
 
 int SkCanvas::saveLayerAlpha(const SkRect* bounds, U8CPU alpha) {
     return this->saveLayerAlpha(bounds, alpha, kARGB_ClipLayer_SaveFlag);
 }
@@ skipping 32 matching lines @@
         recorder will have already recorded the restore).
     */
     if (layer) {
         if (layer->fNext) {
             const SkIPoint& origin = layer->fDevice->getOrigin();
             this->internalDrawDevice(layer->fDevice, origin.x(), origin.y(),
                                      layer->fPaint);
             // reset this, since internalDrawDevice will have set it to true
             fDeviceCMDirty = true;
         }
+        if (layer->fPaint && layer->fPaint->fImageFilter) {

[reed1, 2015/03/26 15:54:03]

the check seems a little fragile, since it somehow knows the predicate being
used in internalSave. I think an explicit flag in the layer, or just always
copying it, would be clearer.

[Stephen White, 2015/03/26 16:18:34]

Done.

+            fMCRec->fMatrix = layer->fStashedMatrix;
+        }
         SkDELETE(layer);
     }
 }
 
 SkSurface* SkCanvas::newSurface(const SkImageInfo& info, const SkSurfaceProps* props) {
     if (NULL == props) {
         props = &fProps;
     }
     return this->onNewSurface(info, *props);
 }
@@ skipping 1502 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }