SkBitmapRegionCanvas bug fix

tools/SkBitmapRegionCanvas.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapRegionCanvas.h"
 #include "SkCanvas.h"
 #include "SkCodecPriv.h"
@@ skipping 134 matching lines @@
         return nullptr;
     }
 
     // Zero the bitmap if the region is not completely within the image.
     // TODO (msarett): Can we make this faster by implementing it to only
     //                 zero parts of the image that we won't overwrite with
     //                 pixels?
     // TODO (msarett): This could be skipped if memory is zero initialized.
     //                 This would matter if this code is moved to Android and
     //                 uses Android bitmaps.
-    if (imageContainsEntireSubset) {
+    if (!imageContainsEntireSubset) {
         bitmap->eraseColor(0);
     }
 
     // Use a canvas to crop and scale to the destination bitmap
     SkCanvas canvas(*bitmap);
     // TODO (msarett): Maybe we can take advantage of the fact that SkRect uses floats?
     SkRect src = SkRect::MakeXYWH((SkScalar) imageSubsetX, (SkScalar) 0,
             (SkScalar) imageSubsetWidth, (SkScalar) imageSubsetHeight);
     SkRect dst = SkRect::MakeXYWH((SkScalar) (outX / sampleSize), (SkScalar) (outY / sampleSize),
             (SkScalar) get_scaled_dimension(imageSubsetWidth, sampleSize),
@@ skipping 11 matching lines @@
     // SkCanvas does not draw to these color types.
     if (kIndex_8_SkColorType == colorType || kGray_8_SkColorType == colorType) {
         return false;
     }
 
     // FIXME: Call virtual function when it lands.
     SkImageInfo info = SkImageInfo::Make(0, 0, colorType, fDecoder->getInfo().alphaType(),
             fDecoder->getInfo().profileType());
     return conversion_possible(info, fDecoder->getInfo());
 }