add ImageGenerator::NewFromData to porting layer

include/core/SkImageGenerator.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageGenerator_DEFINED
 #define SkImageGenerator_DEFINED
 
@@ skipping 15 matching lines @@
  *  If this fails or when the SkDiscardablePixelRef that is
  *  installed into destination is destroyed, it will call
  *  SkDELETE() on the generator.  Therefore, generator should be
  *  allocated with SkNEW() or SkNEW_ARGS().
  *
  *  @param destination Upon success, this bitmap will be
  *  configured and have a pixelref installed.
  *
  *  @return true iff successful.
  */
 SK_API bool SkInstallDiscardablePixelRef(SkImageGenerator*, SkBitmap* destination);

[hal.canary, 2015/01/06 20:06:40]

Since we have a porting layer now, let's add convenience functions:

bool SkInstallDiscardablePixelRef(SkData* data, SkBitmap* dst) {
    return SkInstallDiscardablePixelRef(
            SkImageGenerator::NewFromData(data), dst);
}

bool SkDecodeData(SkData* data, SkBitmap* dst) {
    SkAutoTDelete<SkImageGenerator> gen(SkImageGenerator::NewFromData(data));
    SkImageInfo info;
    if (!gen.get() || !gen->getInfo(&info)) {
        return false;
    }
    if (info.colorType == kIndex_8_SkColorType) {
        SkPMColor colors[256];
        int colorCount = 0;
        size_t rowBytes = info.minRowBytes();
        SkAutoMalloc pixels(info.getSafeSize(rowBytes));
        if (!gen->getPixels(info, autoMalloc.get(), rowBytes, colors,
                            &colorCount)) {
            return false;
        }
        SkAutoTUnref<SkColorTable> colorTable(
                SkNEW_ARGS(SkColorTable, (colors, colorCount)));
        dst->installPixels(info, pixels.detach(), rowBytes, colorTable,
                           &sk_free_release_proc, NULL);
        return true;
    } else {
        SkBitmap bm; 
        bm.allocPixels(info);
        SkAutoLockPixels autoLockPixels(bm);
        if (!gen->getPixels(bm.info(), bm.getPixels(), bm.rowBytes())) {
            return false;
        }
        bm.swap(*dst);
        return true;
    }
}

[hal.canary, 2015/01/06 20:14:48]

Also, 

class SkImage {
    static SkImage* NewFromData(SkData*) {
        return SkImage::NewFromGenerator(SkImageGenerator::NewFromData(data));
    }
}

[reed1, 2015/01/07 16:09:23]

Acknowledged.

 
 
 /**
  *  An interface that allows a purgeable PixelRef (such as a
  *  SkDiscardablePixelRef) to decode and re-decode an image as needed.
  */
 class SK_API SkImageGenerator {
 public:
     /**
      *  The PixelRef which takes ownership of this SkImageGenerator
@@ skipping 62 matching lines @@
      *  rowBytes are both fully defined and non NULL/non 0 or they are both NULL or have NULL or 0
      *  entries only. Having only partial planes/rowBytes information is not supported.
      *
      *  If all planes and rowBytes entries are non NULL or non 0, then it should copy the
      *  associated YUV data into those planes of memory supplied by the caller. It should validate
      *  that the sizes match what it expected. If the sizes do not match, it should return false.
      */
     bool getYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                        SkYUVColorSpace* colorSpace);
 
+    /**
+     *  If the default image decoder system can interpret the specified (encoded) data, then
+     *  this returns a new ImageGenerator for it. Otherwise this returns NULL. Either way
+     *  the caller is still responsible for managing their ownership of the data.
+     */
+    static SkImageGenerator* NewFromData(SkData*);
+
 protected:
     virtual SkData* onRefEncodedData();
     virtual bool onGetInfo(SkImageInfo* info);
     virtual bool onGetPixels(const SkImageInfo& info,
                              void* pixels, size_t rowBytes,
                              SkPMColor ctable[], int* ctableCount);
     virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3]);
     virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                  SkYUVColorSpace* colorSpace);
 };
 
 #endif  // SkImageGenerator_DEFINED