Proposal for SkImageGenerator::canDecodeAndScale API

src/core/SkImageGenerator.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImageGenerator.h"
 #include "SkNextID.h"
 
@@ skipping 181 matching lines @@
         // allocate space for all the pixels.
         ctable->dangerous_overwriteColors(ctStorage, ctCount);
     } else {
         SkASSERT(kIndex_8_SkColorType != bitmap->colorType());
         // we should be the only owner
         SkASSERT(ctable->unique());
     }
     return true;
 }
 
+bool SkImageGenerator::canDecodeAndScale(const SkColorType colorType, const SkScalar scale, SkISize *availableSize, SkISize *lowerSize) {
+    return this->onCanDecodeAndScale(colorType, scale, availableSize, lowerSize);
+}
+
+bool SkImageGenerator::onCanDecodeAndScale(const SkColorType colorType, const SkScalar scale, SkISize *availableSize, SkISize *lowerSize) {
+    if (colorType != fInfo.colorType())
+        return false;
+    if (scale != SK_Scalar1)
+        return false;
+    if (availableSize) {
+        availableSize->fWidth = fInfo.width();
+        availableSize->fHeight = fInfo.height();
+    }
+    if (lowerSize) {
+        availableSize->fWidth = availableSize->fHeight = 0;
+    }
+    return true;
+}
+
+
 #include "SkGraphics.h"
 
 static SkGraphics::ImageGeneratorFromEncodedFactory gFactory;
 
 SkGraphics::ImageGeneratorFromEncodedFactory
 SkGraphics::SetImageGeneratorFromEncodedFactory(ImageGeneratorFromEncodedFactory factory)
 {
     ImageGeneratorFromEncodedFactory prev = gFactory;
     gFactory = factory;
     return prev;
 }
 
 SkImageGenerator* SkImageGenerator::NewFromEncoded(SkData* data) {
     if (nullptr == data) {
         return nullptr;
     }
     if (gFactory) {
         if (SkImageGenerator* generator = gFactory(data)) {
+            SkDebugf("minggle %s generator opaque %d size %d %d", __func__, generator->getInfo().isOpaque(), generator->getInfo().width(), generator->getInfo().height());
             return generator;
         }
     }
+    SkDebugf("minggle %s generator1", __func__);
     return SkImageGenerator::NewFromEncodedImpl(data);
 }