Updates to skimage tool to use it for testing.

src/images/SkImageDecoder_libpng.cpp

 
 /*
  * Copyright 2006 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 "SkImageDecoder.h"
@@ skipping 29 matching lines @@
 };
 
 class SkPNGImageDecoder : public SkImageDecoder {
 public:
     SkPNGImageDecoder() {
         fImageIndex = NULL;
     }
     virtual Format getFormat() const SK_OVERRIDE {
         return kPNG_Format;
     }
+
+    virtual Format onGetFormat(SkStream*) const SK_OVERRIDE;
+
     virtual ~SkPNGImageDecoder() {
         SkDELETE(fImageIndex);
     }
 
 protected:
 #ifdef SK_BUILD_FOR_ANDROID
     virtual bool onBuildTileIndex(SkStream *stream, int *width, int *height) SK_OVERRIDE;
     virtual bool onDecodeRegion(SkBitmap* bitmap, const SkIRect& region) SK_OVERRIDE;
 #endif
     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
@@ skipping 1012 matching lines @@
         srcImage += bitmap.rowBytes();
     }
 
     png_write_end(png_ptr, info_ptr);
 
     /* clean up after the write, and free any memory allocated */
     png_destroy_write_struct(&png_ptr, &info_ptr);
     return true;
 }
 
+static bool is_png(SkStream* stream) {
+    char buf[PNG_BYTES_TO_CHECK];
+    if (stream->read(buf, PNG_BYTES_TO_CHECK) == PNG_BYTES_TO_CHECK &&
+        !png_sig_cmp((png_bytep) buf, (png_size_t)0, PNG_BYTES_TO_CHECK)) {
+        return true;
+    }
+    return false;
+}
+
+SkImageDecoder::Format SkPNGImageDecoder::onGetFormat(SkStream* stream) const {
+    if (is_png(stream)) {
+        return kPNG_Format;
+    }
+    return kUnknown_Format;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 DEFINE_DECODER_CREATOR(PNGImageDecoder);
 DEFINE_ENCODER_CREATOR(PNGImageEncoder);
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "SkTRegistry.h"
 
 SkImageDecoder* sk_libpng_dfactory(SkStream* stream) {
-    char buf[PNG_BYTES_TO_CHECK];
-    if (stream->read(buf, PNG_BYTES_TO_CHECK) == PNG_BYTES_TO_CHECK &&
-        !png_sig_cmp((png_bytep) buf, (png_size_t)0, PNG_BYTES_TO_CHECK)) {
+    if (is_png(stream)) {
         return SkNEW(SkPNGImageDecoder);
     }
     return NULL;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? SkNEW(SkPNGImageEncoder) : NULL;
 }
 
 static SkTRegistry<SkImageEncoder*, SkImageEncoder::Type> gEReg(sk_libpng_efactory);
 static SkTRegistry<SkImageDecoder*, SkStream*> gDReg(sk_libpng_dfactory);