optimize the disable-caching case for SkImage::readPixels

src/core/SkImageCacherator.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 "SkBitmapCache.h"
 #include "SkImage_Base.h"
@@ skipping 90 matching lines @@
             return false;
         }
         if (!bitmap->tryAllocPixels(fInfo, nullptr, full.getColorTable())) {
             return false;
         }
         return full.readPixels(bitmap->info(), bitmap->getPixels(), bitmap->rowBytes(),
                                fOrigin.x(), fOrigin.y());
     }
 }
 
+bool SkImageCacherator::directGeneratePixels(const SkImageInfo& info, void* pixels, size_t rb,
+                                             int srcX, int srcY) {
+    ScopedGenerator generator(this);
+    const SkImageInfo& genInfo = generator->getInfo();
+    // Currently generators do not natively handle subsets, so check that first.
+    if (srcX || srcY || genInfo.width() != info.width() || genInfo.height() != info.height()) {
+        return false;
+    }
+    return generator->getPixels(info, pixels, rb);
+}
+
 //////////////////////////////////////////////////////////////////////////////////////////////////
 
+bool SkImageCacherator::lockAsBitmapOnlyIfAlreadyCached(SkBitmap* bitmap) {
+    return SkBitmapCache::Find(fUniqueID, bitmap) && check_output_bitmap(*bitmap, fUniqueID);
+}
+
 bool SkImageCacherator::tryLockAsBitmap(SkBitmap* bitmap, const SkImage* client,
                                         SkImage::CachingHint chint) {
-    if (SkBitmapCache::Find(fUniqueID, bitmap)) {
-        return check_output_bitmap(*bitmap, fUniqueID);
+    if (this->lockAsBitmapOnlyIfAlreadyCached(bitmap)) {
+        return true;
     }
-
     if (!this->generateBitmap(bitmap)) {
         return false;
     }
 
     bitmap->pixelRef()->setImmutableWithID(fUniqueID);
     if (SkImage::kAllow_CachingHint == chint) {
         SkBitmapCache::Add(fUniqueID, *bitmap);
         if (client) {
             as_IB(client)->notifyAddedToCache();
         }
@@ skipping 203 matching lines @@
 }
 
 #else
 
 GrTexture* SkImageCacherator::lockAsTexture(GrContext* ctx, const GrTextureParams&,
                                             const SkImage* client, SkImage::CachingHint) {
     return nullptr;
 }
 
 #endif