check for inputs before reporting asColorFilter

src/effects/SkColorFilterImageFilter.cpp

Index: src/effects/SkColorFilterImageFilter.cpp
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index fdf6de7b76daf755f2fea5d49c87a753374e3cb7..1f7f7505f32c95b1454f9cac96cc85ad0a130bcf 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -21,13 +21,13 @@ SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
         return NULL;
     }
 
-    SkColorFilter* inputColorFilter;
-    if (input && input->asColorFilter(&inputColorFilter)) {
-        SkAutoUnref autoUnref(inputColorFilter);
-        SkAutoTUnref<SkColorFilter> newCF(cf->newComposed(inputColorFilter));
-        if (newCF) {
-            return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
-        }
+    SkColorFilter* inputCF;
+    if (!cropRect && input && input->asColorFilter(&inputCF)) {

[Stephen White, 2015/03/04 19:38:37]

I'm not sure this !cropRect check is correct. I think it should be valid to
collapse a chain of CFIFs, even if the last one has a crop rect -- it'll get
applied by this CFIF at draw time. It's only the intermediate (input) CFs that
can't have crop rects, which is checked in asColorFilter() below.

For your purposes, calling asColorFilter() on the final CFIF (and checking that
it has a NULL input) should be enough, since it will do the crop rect check that
we don't want here.

[reed1, 2015/03/04 20:00:58]

Agreed.

+        // This is an optimization, as it collapses the hierarchy by just combining the
+        // colorfilters into a single imagefilter.
+        SkAutoUnref autoUnref(inputCF);
+        SkAutoTUnref<SkColorFilter> newCF(SkColorFilter::CreateComposeFilter(cf, inputCF));
+        return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
     }
 
     return SkNEW_ARGS(SkColorFilterImageFilter, (cf, input, cropRect, uniqueID));
@@ -86,10 +86,13 @@ bool SkColorFilterImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& sourc
 }
 
 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.
+        SkASSERT(!this->getInput(0) || !this->getInput(0)->asColorFilter(NULL));
         if (filter) {
-            *filter = fColorFilter;
-            fColorFilter->ref();
+            *filter = SkRef(fColorFilter);
         }
         return true;
     }