Test scaling for small images

include/codec/SkCodec.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodec_DEFINED
 #define SkCodec_DEFINED
 
@@ skipping 37 matching lines @@
     const SkImageInfo& getInfo() const { return fInfo; }
 
     /**
      *  Return a size that approximately supports the desired scale factor.
      *  The codec may not be able to scale efficiently to the exact scale
      *  factor requested, so return a size that approximates that scale.
      *  The returned value is the codec's suggestion for the closest valid
      *  scale that it can natively support
      */
     SkISize getScaledDimensions(float desiredScale) const {
+        // Negative and zero scales are errors.
+        SkASSERT(desiredScale > 0.0f);
+        if (desiredScale <= 0.0f) {
+            return SkISize::Make(0, 0);
+        }
+
+        // Upscaling is not supported. Return the original size if the client
+        // requests an upscale.
+        if (desiredScale >= 1.0f) {
+            return this->getInfo().dimensions();
+        }
         return this->onGetScaledDimensions(desiredScale);
     }
 
     /**
      *  Return (via desiredSubset) a subset which can decoded from this codec,
      *  or false if this codec cannot decode subsets or anything similar to
      *  desiredSubset.
      *
      *  @param desiredSubset In/out parameter. As input, a desired subset of
      *      the original bounds (as specified by getInfo). If true is returned,
@@ skipping 195 matching lines @@
     SkStream* stream() {
         return fStream.get();
     }
 
 private:
     const SkImageInfo       fInfo;
     SkAutoTDelete<SkStream> fStream;
     bool                    fNeedsRewind;
 };
 #endif // SkCodec_DEFINED