Revert of remove unused SkCachingPixelRef

src/lazy/SkCachingPixelRef.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCachingPixelRef.h"
+#include "SkBitmapCache.h"
+#include "SkRect.h"
+
+bool SkCachingPixelRef::Install(SkImageGenerator* generator,
+                                SkBitmap* dst) {
+    SkASSERT(dst != nullptr);
+    if (nullptr == generator) {
+        return false;
+    }
+    const SkImageInfo info = generator->getInfo();
+    if (!dst->setInfo(info)) {
+        delete generator;
+        return false;
+    }
+    SkAutoTUnref<SkCachingPixelRef> ref(new SkCachingPixelRef(info, generator, dst->rowBytes()));
+    dst->setPixelRef(ref);
+    return true;
+}
+
+SkCachingPixelRef::SkCachingPixelRef(const SkImageInfo& info,
+                                     SkImageGenerator* generator,
+                                     size_t rowBytes)
+    : INHERITED(info)
+    , fImageGenerator(generator)
+    , fErrorInDecoding(false)
+    , fRowBytes(rowBytes) {
+    SkASSERT(fImageGenerator != nullptr);
+}
+SkCachingPixelRef::~SkCachingPixelRef() {
+    delete fImageGenerator;
+    // Assert always unlock before unref.
+}
+
+bool SkCachingPixelRef::onNewLockPixels(LockRec* rec) {
+    if (fErrorInDecoding) {
+        return false;  // don't try again.
+    }
+
+    const SkImageInfo& info = this->info();
+    if (!SkBitmapCache::Find(
+                this->getGenerationID(), info.bounds(), &fLockedBitmap)) {
+        // Cache has been purged, must re-decode.
+        if (!fLockedBitmap.tryAllocPixels(info, fRowBytes)) {
+            fErrorInDecoding = true;
+            return false;
+        }
+        if (!fImageGenerator->getPixels(info, fLockedBitmap.getPixels(), fRowBytes)) {
+            fErrorInDecoding = true;
+            return false;
+        }
+        fLockedBitmap.setImmutable();
+        SkBitmapCache::Add(this, info.bounds(), fLockedBitmap);
+    }
+
+    // Now bitmap should contain a concrete PixelRef of the decoded image.
+    void* pixels = fLockedBitmap.getPixels();
+    SkASSERT(pixels != nullptr);
+    rec->fPixels = pixels;
+    rec->fColorTable = nullptr;
+    rec->fRowBytes = fLockedBitmap.rowBytes();
+    return true;
+}
+
+void SkCachingPixelRef::onUnlockPixels() {
+    fLockedBitmap.reset();
+}