check for inputs before reporting asColorFilter

src/effects/SkColorFilterImageFilter.cpp

 /*
  * Copyright 2012 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 "SkColorFilterImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkColorMatrixFilter.h"
 #include "SkDevice.h"
 #include "SkColorFilter.h"
 #include "SkReadBuffer.h"
 #include "SkTableColorFilter.h"
 #include "SkWriteBuffer.h"
 
 SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID) {
     if (NULL == cf) {
         return NULL;
     }
 
-    SkColorFilter* inputColorFilter;
-    if (input && input->asColorFilter(&inputColorFilter)) {
-        SkAutoUnref autoUnref(inputColorFilter);
-        SkAutoTUnref<SkColorFilter> newCF(cf->newComposed(inputColorFilter));
+    SkColorFilter* inputCF;
+    if (input && input->asColorFilter(&inputCF)) {
+        // This is an optimization, as it collapses the hierarchy by just combining the two
+        // colorfilters into a single one, which the new imagefilter will wrap.
+        SkAutoUnref autoUnref(inputCF);
+        SkAutoTUnref<SkColorFilter> newCF(SkColorFilter::CreateComposeFilter(cf, inputCF));
         if (newCF) {
             return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
         }
     }
 
     return SkNEW_ARGS(SkColorFilterImageFilter, (cf, input, cropRect, uniqueID));
 }
 
 SkColorFilterImageFilter::SkColorFilterImageFilter(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID)
@@ skipping 41 matching lines @@
     paint.setColorFilter(fColorFilter);
     canvas.drawSprite(src, srcOffset.fX - bounds.fLeft, srcOffset.fY - bounds.fTop, &paint);
 
     *result = device.get()->accessBitmap(false);
     offset->fX = bounds.fLeft;
     offset->fY = bounds.fTop;
     return true;
 }
 
 bool SkColorFilterImageFilter::asColorFilter(SkColorFilter** filter) const {
-    if (!cropRectIsSet()) {
+    if (!this->cropRectIsSet()) {
+        SkASSERT(1 == this->countInputs());
+        // Since our factory has already performed the collapse optimization, we can assert that
+        // if we have an input, it is *not* also a colorfilter.

[Stephen White, 2015/03/05 18:52:18]

Since we're now limiting the amount of collapsing we do, I think this may no
longer be true.

I suspect this will assert with >4 color filters composed.

+        SkASSERT(!this->getInput(0) || !this->getInput(0)->asColorFilter(NULL));
         if (filter) {
-            *filter = fColorFilter;
-            fColorFilter->ref();
+            *filter = SkRef(fColorFilter);
         }
         return true;
     }
     return false;
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkColorFilterImageFilter::toString(SkString* str) const {
     str->appendf("SkColorFilterImageFilter: (");
 
     str->appendf("input: (");
 
     if (this->getInput(0)) {
         this->getInput(0)->toString(str);
     }
 
     str->appendf(") color filter: ");
     fColorFilter->toString(str);
 
     str->append(")");
 }
 #endif