always scale to an integer; compensate for fractional image sizes by leaving the fractional scale i…

tests/ScaledImageCache.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 "Test.h"
 #include "SkCanvas.h"
 #include "SkGraphics.h"
 #include "SkBitmapCache.h"
 
 static const int kCanvasSize = 1;
 static const int kBitmapSize = 16;
 static const int kScale = 8;
 
 static bool is_in_scaled_image_cache(const SkBitmap& orig,
                                      SkScalar xScale,
                                      SkScalar yScale) {
     SkBitmap scaled;
-    return SkBitmapCache::Find(orig, SkScalarInvert(xScale), SkScalarInvert(yScale), &scaled);
+    float roundedImageWidth = SkScalarRoundToScalar(orig.width() * xScale);
+    float roundedImageHeight = SkScalarRoundToScalar(orig.height() * xScale);
+    return SkBitmapCache::Find(orig, roundedImageWidth, roundedImageHeight, &scaled);
 }
 
 // Draw a scaled bitmap, then return true iff it has been cached.
 static bool test_scaled_image_cache_useage() {
     SkAutoTUnref<SkCanvas> canvas(
             SkCanvas::NewRasterN32(kCanvasSize, kCanvasSize));
     SkBitmap bitmap;
     SkAssertResult(bitmap.allocN32Pixels(kBitmapSize, kBitmapSize));
     bitmap.eraseColor(0xFFFFFFFF);
     SkScalar scale = SkIntToScalar(kScale);
@@ skipping 32 matching lines @@
 
     SkGraphics::SetImageCacheTotalByteLimit(0);  // clear cache
     SkGraphics::SetImageCacheTotalByteLimit(2 * size);
     SkGraphics::SetImageCacheSingleAllocationByteLimit(size / 2);  // too small
 
     REPORTER_ASSERT(reporter, !test_scaled_image_cache_useage());
 
     SkGraphics::SetImageCacheSingleAllocationByteLimit(originalAllocationLimit);
     SkGraphics::SetImageCacheTotalByteLimit(originalByteLimit);
 }