Move all knowledge of X sampling into SkScaledCodec

src/codec/SkCodec_libico.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 "SkBmpCodec.h"
 #include "SkCodec_libico.h"
 #include "SkCodec_libpng.h"
@@ skipping 188 matching lines @@
     , fEmbeddedCodecs(codecs)
 {}
 
 /*
  * Chooses the best dimensions given the desired scale
  */
 SkISize SkIcoCodec::onGetScaledDimensions(float desiredScale) const { 
     // We set the dimensions to the largest candidate image by default.
     // Regardless of the scale request, this is the largest image that we
     // will decode.
-    if (desiredScale >= 1.0) {
-        return this->getInfo().dimensions();
-    }
-
     int origWidth = this->getInfo().width();
     int origHeight = this->getInfo().height();
     float desiredSize = desiredScale * origWidth * origHeight;
     // At least one image will have smaller error than this initial value
     float minError = ((float) (origWidth * origHeight)) - desiredSize + 1.0f;
     int32_t minIndex = -1;
     for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
         int width = fEmbeddedCodecs->operator[](i)->getInfo().width();
         int height = fEmbeddedCodecs->operator[](i)->getInfo().height();
         float error = SkTAbs(((float) (width * height)) - desiredSize);
         if (error < minError) {
             minError = error;
             minIndex = i;
         }
     }
     SkASSERT(minIndex >= 0);
 
     return fEmbeddedCodecs->operator[](minIndex)->getInfo().dimensions();
 }
 
+bool SkIcoCodec::onDimensionsSupported(const SkISize& dim) {
+    // FIXME: Cache the index from onGetScaledDimensions?
+    for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
+        if (fEmbeddedCodecs->operator[](i)->getInfo().dimensions() == dim) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 /*
  * Initiates the Ico decode
  */
 SkCodec::Result SkIcoCodec::onGetPixels(const SkImageInfo& dstInfo,
                                         void* dst, size_t dstRowBytes,
                                         const Options& opts, SkPMColor* ct,
                                         int* ptr) {
     if (opts.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
@@ skipping 36 matching lines @@
                     kInvalidScale == result) {
                 SkCodecPrintf("Warning: Attempt to decode candidate ico failed.\n");
                 continue;
             }
 
             // On success or partial success, return the result
             return result;
         }
     }
 
+    // This should never be reached, since onDimensionsSupported should have rejected the
+    // dimensions sooner.
+    SkASSERT(false);
     SkCodecPrintf("Error: No matching candidate image in ico.\n");
     return result;
 }