Add GrGpuResource::CacheAccess

Internal only helper class for manipulating and accessing cache keys.

BUG=skia:2889

Review URL: https://codereview.chromium.org/703303003

1 files changed, 96 insertions, 0 deletions

diff --git a/src/gpu/GrGpuResourceCacheAccess.h b/src/gpu/GrGpuResourceCacheAccess.h
new file mode 100644
index 0000000000..af5c05464b
--- /dev/null
+++ b/src/gpu/GrGpuResourceCacheAccess.h
@@ -0,0 +1,96 @@
+
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrGpuResourceCacheAccess_DEFINED
+#define GrGpuResourceCacheAccess_DEFINED
+
+#include "GrGpuResource.h"
+
+/**
+ * This class allows code internal to Skia privileged access to manage the cache keys of a
+ * GrGpuResource object.
+ */
+class GrGpuResource::CacheAccess {
+public:
+    /**
+     * Sets a content key for the resource. If the resource was previously cached as scratch it will
+     * be converted to a content resource. Currently this may only be called once per resource. It
+     * fails if there is already a resource with the same content key. TODO: make this supplant the
+     * resource that currently is using the content key, allow resources' content keys to change,
+     * and allow removal of a content key to convert a resource back to scratch.
+     */
+    bool setContentKey(const GrResourceKey& contentKey) {
+        return fResource->setContentKey(contentKey);
+    }
+
+    /**
+     * Used by legacy cache to attach a cache entry. This is to be removed soon.
+     */
+    void setCacheEntry(GrResourceCacheEntry* cacheEntry) {
+        // GrResourceCache never changes the cacheEntry once one has been added.
+        SkASSERT(NULL == cacheEntry || NULL == fResource->fCacheEntry);
+        fResource->fCacheEntry = cacheEntry;
+    }
+
+    /**
+     * Is the resource in the legacy cache? This is to be removed soon.
+     */
+    bool isInCache() const { return SkToBool(fResource->fCacheEntry); }
+
+    /**
+     * Returns the cache entry for the legacy cache. This is to be removed soon.
+     */
+    GrResourceCacheEntry* getCacheEntry() const { return fResource->fCacheEntry; }
+
+    /**
+     * Is the resource currently cached as scratch? This means it has a valid scratch key and does
+     * not have a content key.
+     */
+    bool isScratch() const {
+        SkASSERT(fResource->fScratchKey.isScratch());
+        return NULL == this->getContentKey() && !fResource->fScratchKey.isNullScratch();
+    }
+
+    /** 
+     * If this resource can be used as a scratch resource this returns a valid scratch key.
+     * Otherwise it returns a key for which isNullScratch is true. The resource may currently be
+     * used as content resource rather than scratch. Check isScratch().
+     */
+    const GrResourceKey& getScratchKey() const { return fResource->fScratchKey; }
+
+    /**
+     * If the resource is currently cached by a content key, the key is returned, otherwise NULL.
+     */
+    const GrResourceKey* getContentKey() const {
+        if (fResource->fContentKeySet) {
+            return &fResource->fContentKey;
+        }
+        return NULL;
+    }
+
+private:
+    CacheAccess(GrGpuResource* resource) : fResource(resource) { }
+    CacheAccess(const CacheAccess& that) : fResource(that.fResource) { }
+    CacheAccess& operator=(const CacheAccess&); // unimpl
+
+    // No taking addresses of this type.
+    const CacheAccess* operator&() const;
+    CacheAccess* operator&();
+
+    GrGpuResource* fResource;
+
+    friend class GrGpuResource; // to construct/copy this type.
+};
+
+inline GrGpuResource::CacheAccess GrGpuResource::cacheAccess() { return CacheAccess(this); }
+
+inline const GrGpuResource::CacheAccess GrGpuResource::cacheAccess() const {
+    return CacheAccess(const_cast<GrGpuResource*>(this));
+}
+
+#endif