Add toString methods to SkImageFilter-derived classes

src/effects/SkAlphaThresholdFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAlphaThresholdFilter.h"
 #include "SkBitmap.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkRegion.h"
 
 class SK_API SkAlphaThresholdFilterImpl : public SkImageFilter {
 public:
     SkAlphaThresholdFilterImpl(const SkRegion& region, SkScalar innerThreshold,
                                SkScalar outerThreshold, SkImageFilter* input);
 
+    SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkAlphaThresholdFilterImpl)
 
 protected:
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
                                      const SkIRect& bounds) const SK_OVERRIDE;
@@ skipping 338 matching lines @@
                                                   (U8CPU)(SkColorGetG(source) * scale),
                                                   (U8CPU)(SkColorGetB(source) * scale));
                 }
             }
             dptr[y * dst->width() + x] = output_color;
         }
     }
 
     return true;
 }
+
+#ifndef SK_IGNORE_TO_STRING
+void SkAlphaThresholdFilterImpl::toString(SkString* str) const {
+    str->appendf("SkAlphaThresholdImageFilter: (");
+    str->appendf("inner: %f outer: %f", fInnerThreshold, fOuterThreshold);
+    str->append(")");
+}
+#endif
+