add toString to SkImage

src/image/SkImage.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkImagePriv.h"
 #include "SkImage_Base.h"
 #include "SkReadPixelsRec.h"
+#include "SkString.h"
 #include "SkSurface.h"
 
 uint32_t SkImage::NextUniqueID() {
     static int32_t gUniqueID;
 
     // never return 0;
     uint32_t id;
     do {
         id = sk_atomic_inc(&gUniqueID) + 1;
     } while (0 == id);
@@ skipping 48 matching lines @@
     return NULL;
 }
 
 SkSurface* SkImage::newSurface(const SkImageInfo& info, const SkSurfaceProps* props) const {
     if (NULL == props) {
         props = &as_IB(this)->props();
     }
     return as_IB(this)->onNewSurface(info, *props);
 }
 
+const char* SkImage::toString(SkString* str) const {
+    str->appendf("image: (id:%d (%d, %d) %s)", this->uniqueID(), this->width(), this->height(),
+                 this->isOpaque() ? "opaque" : "");
+    return str->c_str();
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 static bool raster_canvas_supports(const SkImageInfo& info) {
     switch (info.colorType()) {
         case kN32_SkColorType:
             return kUnpremul_SkAlphaType != info.alphaType();
         case kRGB_565_SkColorType:
             return true;
         case kAlpha_8_SkColorType:
             return true;
@@ skipping 12 matching lines @@
     SkBitmap bm;
     bm.installPixels(dstInfo, dstPixels, dstRowBytes);
     SkCanvas canvas(bm);
 
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
     canvas.drawImage(this, -SkIntToScalar(srcX), -SkIntToScalar(srcY), &paint);
 
     return true;
 }