Use colorfilter instead of imagefilter when possible

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"
+#include "SkColorFilter.h"
 #include "SkDeviceImageFilterProxy.h"
 #include "SkDraw.h"
 #include "SkDrawable.h"
 #include "SkDrawFilter.h"
 #include "SkDrawLooper.h"
 #include "SkErrorInternals.h"
 #include "SkImage.h"
 #include "SkMetaData.h"
 #include "SkPathOps.h"
 #include "SkPatchUtils.h"
@@ skipping 271 matching lines @@
     SkCanvas*       fCanvas;
     const DeviceCM* fCurrLayer;
     const SkPaint*  fPaint;     // May be null.
     SkBool8         fSkipEmptyClips;
 
     typedef SkDraw INHERITED;
 };
 
 /////////////////////////////////////////////////////////////////////////////
 
+static SkPaint* set_if_needed(SkLazyPaint* lazy, const SkPaint& orig) {
+    return lazy->isValid() ? lazy->get() : lazy->set(orig);
+}
+
+/**
+ *  If the paint has an imagefilter, but it can be simplified to just a colorfilter, return that
+ *  colorfilter, else return NULL.
+ */
+static SkColorFilter* image_to_color_filter(const SkPaint& paint) {
+#ifdef SK_SUPPORT_LEGACY_IMAGEFILTER_TO_COLORFILTER
+    return NULL;
+#else
+    SkImageFilter* imgf = paint.getImageFilter();
+    if (!imgf) {
+        return NULL;
+    }
+
+    SkColorFilter* imgCF;
+    if (!imgf->asAColorFilter(&imgCF)) {
+        return NULL;
+    }
+
+    SkColorFilter* paintCF = paint.getColorFilter();
+    if (NULL == paintCF) {
+        // there is no existing paint colorfilter, so we can just return the imagefilter's
+        return imgCF;
+    }
+
+    // The paint has both a colorfilter(paintCF) and an imagefilter-which-is-a-colorfilter(imgCF)
+    // and we need to combine them into a single colorfilter.
+    SkAutoTUnref<SkColorFilter> autoImgCF(imgCF);
+    return SkColorFilter::CreateComposeFilter(imgCF, paintCF);
+#endif
+}
+
 class AutoDrawLooper {
 public:
     AutoDrawLooper(SkCanvas* canvas, const SkSurfaceProps& props, const SkPaint& paint,
                    bool skipLayerForImageFilter = false,
                    const SkRect* bounds = NULL) : fOrigPaint(paint) {
         fCanvas = canvas;
         fFilter = canvas->getDrawFilter();
         fPaint = &fOrigPaint;
         fSaveCount = canvas->getSaveCount();
         fTempLayerForImageFilter = false;
         fDone = false;
 
-        if (!skipLayerForImageFilter && fOrigPaint.getImageFilter()) {
+        SkColorFilter* simplifiedCF = image_to_color_filter(fOrigPaint);
+        if (simplifiedCF) {
+            SkPaint* paint = set_if_needed(&fLazyPaintInit, fOrigPaint);
+            paint->setColorFilter(simplifiedCF)->unref();
+            paint->setImageFilter(NULL);
+            fPaint = paint;
+        }
+
+        if (!skipLayerForImageFilter && fPaint->getImageFilter()) {
             /**
              *  We implement ImageFilters for a given draw by creating a layer, then applying the
              *  imagefilter to the pixels of that layer (its backing surface/image), and then
              *  we call restore() to xfer that layer to the main canvas.
              *
              *  1. SaveLayer (with a paint containing the current imagefilter and xfermode)
              *  2. Generate the src pixels:
              *      Remove the imagefilter and the xfermode from the paint that we (AutoDrawLooper)
              *      return (fPaint). We then draw the primitive (using srcover) into a cleared
              *      buffer/surface.
              *  3. Restore the layer created in #1
              *      The imagefilter is passed the buffer/surface from the layer (now filled with the
              *      src pixels of the primitive). It returns a new "filtered" buffer, which we
              *      draw onto the previous layer using the xfermode from the original paint.
              */
             SkPaint tmp;
-            tmp.setImageFilter(fOrigPaint.getImageFilter());
-            tmp.setXfermode(fOrigPaint.getXfermode());
+            tmp.setImageFilter(fPaint->getImageFilter());
+            tmp.setXfermode(fPaint->getXfermode());
             (void)canvas->internalSaveLayer(bounds, &tmp, SkCanvas::kARGB_ClipLayer_SaveFlag,
                                             SkCanvas::kFullLayer_SaveLayerStrategy);
             fTempLayerForImageFilter = true;
             // we remove the imagefilter/xfermode inside doNext()
         }
 
         if (SkDrawLooper* looper = paint.getLooper()) {
             void* buffer = fLooperContextAllocator.reserveT<SkDrawLooper::Context>(
                     looper->contextSize());
             fLooperContext = looper->createContext(canvas, buffer);
             fIsSimple = false;
         } else {
             fLooperContext = NULL;
             // can we be marked as simple?
             fIsSimple = !fFilter && !fTempLayerForImageFilter;
         }
 
         uint32_t oldFlags = paint.getFlags();
         fNewPaintFlags = filter_paint_flags(props, oldFlags);
         if (fIsSimple && (fNewPaintFlags != oldFlags)) {
-            SkPaint* paint = fLazyPaint.set(fOrigPaint);
+            SkPaint* paint = set_if_needed(&fLazyPaintInit, fOrigPaint);
             paint->setFlags(fNewPaintFlags);
             fPaint = paint;
             // if we're not simple, doNext() will take care of calling setFlags()
         }
     }
 
     ~AutoDrawLooper() {
         if (fTempLayerForImageFilter) {
             fCanvas->internalRestore();
         }
@@ skipping 10 matching lines @@
             return false;
         } else if (fIsSimple) {
             fDone = true;
             return !fPaint->nothingToDraw();
         } else {
             return this->doNext(drawType);
         }
     }
 
 private:
-    SkLazyPaint     fLazyPaint;
+    SkLazyPaint     fLazyPaintInit; // base paint storage in case we need to modify it
+    SkLazyPaint     fLazyPaintPerLooper;  // per-draw-looper storage, so the looper can modify it
     SkCanvas*       fCanvas;
     const SkPaint&  fOrigPaint;
     SkDrawFilter*   fFilter;
     const SkPaint*  fPaint;
     int             fSaveCount;
     uint32_t        fNewPaintFlags;
     bool            fTempLayerForImageFilter;
     bool            fDone;
     bool            fIsSimple;
     SkDrawLooper::Context* fLooperContext;
     SkSmallAllocator<1, 32> fLooperContextAllocator;
 
     bool doNext(SkDrawFilter::Type drawType);
 };
 
 bool AutoDrawLooper::doNext(SkDrawFilter::Type drawType) {
     fPaint = NULL;
     SkASSERT(!fIsSimple);
     SkASSERT(fLooperContext || fFilter || fTempLayerForImageFilter);
 
-    SkPaint* paint = fLazyPaint.set(fOrigPaint);
+    SkPaint* paint = fLazyPaintPerLooper.set(fLazyPaintInit.isValid() ?
+                                             *fLazyPaintInit.get() : fOrigPaint);
     paint->setFlags(fNewPaintFlags);
 
     if (fTempLayerForImageFilter) {
         paint->setImageFilter(NULL);
         paint->setXfermode(NULL);
     }
 
     if (fLooperContext && !fLooperContext->next(fCanvas, paint)) {
         fDone = true;
         return false;
@@ skipping 2176 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }