simplify bitmap scaler and cache

src/core/SkBitmapController.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 "SkBitmap.h"
 #include "SkBitmapController.h"
 #include "SkMatrix.h"
 #include "SkTemplates.h"
 
+// RESIZE_LANCZOS3 is another good option, but chrome prefers mitchell at the moment
+#define kHQ_RESIZE_METHOD   SkBitmapScaler::RESIZE_MITCHELL
+
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static bool valid_for_drawing(const SkBitmap& bm) {
     if (0 == bm.width() || 0 == bm.height()) {
         return false;   // nothing to draw
     }
     if (nullptr == bm.pixelRef()) {
         return false;   // no pixels to read
     }
     if (bm.getTexture()) {
@@ skipping 87 matching lines @@
         if (!fInvMatrix.decomposeScale(&scale)) {
             return false;
         }
         invScaleX = scale.width();
         invScaleY = scale.height();
     }
     if (SkScalarNearlyEqual(invScaleX, 1) && SkScalarNearlyEqual(invScaleY, 1)) {
         return false; // no need for HQ
     }
     
-    SkScalar trueDestWidth  = origBitmap.width() / invScaleX;
-    SkScalar trueDestHeight = origBitmap.height() / invScaleY;
-    SkScalar roundedDestWidth = SkScalarRoundToScalar(trueDestWidth);
-    SkScalar roundedDestHeight = SkScalarRoundToScalar(trueDestHeight);
+    const int dstW = SkScalarRoundToScalar(origBitmap.width() / invScaleX);
+    const int dstH = SkScalarRoundToScalar(origBitmap.height() / invScaleY);
     
-    if (!SkBitmapCache::Find(origBitmap, roundedDestWidth, roundedDestHeight, &fResultBitmap)) {
+    if (!SkBitmapCache::FindWH(origBitmap, dstW, dstH, &fResultBitmap)) {
         SkAutoPixmapUnlock src;
         if (!origBitmap.requestLock(&src)) {
             return false;
         }
-        if (!SkBitmapScaler::Resize(&fResultBitmap, src.pixmap(), SkBitmapScaler::RESIZE_BEST,
-                                    roundedDestWidth, roundedDestHeight,
-                                    SkResourceCache::GetAllocator())) {
+        if (!SkBitmapScaler::Resize(&fResultBitmap, src.pixmap(), kHQ_RESIZE_METHOD,
+                                    dstW, dstH, SkResourceCache::GetAllocator())) {
             return false; // we failed to create fScaledBitmap
         }
         
         SkASSERT(fResultBitmap.getPixels());
         fResultBitmap.setImmutable();
-        SkBitmapCache::Add(origBitmap, roundedDestWidth, roundedDestHeight, fResultBitmap);
+        SkBitmapCache::AddWH(origBitmap, dstW, dstH, fResultBitmap);
     }
     
     SkASSERT(fResultBitmap.getPixels());
     
-    fInvMatrix.postScale(roundedDestWidth / origBitmap.width(),
-                         roundedDestHeight / origBitmap.height());
+    fInvMatrix.postScale(SkIntToScalar(dstW) / origBitmap.width(),
+                         SkIntToScalar(dstH) / origBitmap.height());
     fQuality = kLow_SkFilterQuality;
     return true;
 }
 
 /*
  *  Modulo internal errors, this should always succeed *if* the matrix is downscaling
  *  (in this case, we have the inverse, so it succeeds if fInvMatrix is upscaling)
  */
 bool SkDefaultBitmapControllerState::processMediumRequest(const SkBitmap& origBitmap) {
     SkASSERT(fQuality <= kMedium_SkFilterQuality);
@@ skipping 63 matching lines @@
                   fResultBitmap.getColorTable());
 }
 
 SkBitmapController::State* SkDefaultBitmapController::onRequestBitmap(const SkBitmap& bm,
                                                                       const SkMatrix& inverse,
                                                                       SkFilterQuality quality,
                                                                       void* storage, size_t size) {
     return SkInPlaceNewCheck<SkDefaultBitmapControllerState>(storage, size, bm, inverse, quality);
 }