Add toString methods to SkImageFilter-derived classes

src/effects/SkXfermodeImageFilter.cpp

 /*
  * Copyright 2013 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 "SkXfermodeImageFilter.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
@@ skipping 80 matching lines @@
                       SkIntToScalar(foregroundOffset.fY), &paint);
     canvas.clipRect(SkRect::Make(foregroundBounds), SkRegion::kDifference_Op);
     paint.setColor(SK_ColorTRANSPARENT);
     canvas.drawPaint(paint);
     *dst = device->accessBitmap(false);
     offset->fX = bounds.left();
     offset->fY = bounds.top();
     return true;
 }
 
+#ifndef SK_IGNORE_TO_STRING
+void SkXfermodeImageFilter::toString(SkString* str) const {
+    str->appendf("SkXfermodeImageFilter: (");
+    str->appendf("xfermode: (");
+    if (fMode) {
+        fMode->toString(str);
+    }
+    str->append("))");
+}
+#endif
+
 #if SK_SUPPORT_GPU
 
 bool SkXfermodeImageFilter::canFilterImageGPU() const {
     return fMode && fMode->asFragmentProcessor(NULL, NULL) && !cropRectIsSet();
 }
 
 bool SkXfermodeImageFilter::filterImageGPU(Proxy* proxy,
                                            const SkBitmap& src,
                                            const Context& ctx,
                                            SkBitmap* result,
@@ skipping 47 matching lines @@
     paint.addColorProcessor(xferProcessor)->unref();
     context->drawRect(paint, SkMatrix::I(), srcRect);
 
     offset->fX = backgroundOffset.fX;
     offset->fY = backgroundOffset.fY;
     WrapTexture(dst, src.width(), src.height(), result);
     return true;
 }
 
 #endif
+