Reopened: Caching the result of readPixelsSupported

src/core/SkTHashCache.h

Index: src/core/SkTHashCache.h
diff --git a/src/core/SkTHashCache.h b/src/core/SkTHashCache.h
new file mode 100644
index 0000000000000000000000000000000000000000..a8b8733993b0080591351b2f9b3f6a02e2c89c53
--- /dev/null
+++ b/src/core/SkTHashCache.h
@@ -0,0 +1,79 @@
+/*
+ * 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 SkTHASHCACHE_DEFINED
+#define	SkTHASHCACHE_DEFINED
+
+#include "SkTypes.h"
+#include "SkTDArray.h"
+#include "SkTDynamicHash.h"
+
+template <typename T,
+typename Key,
+typename Traits = T,
+int kGrowPercent = 75 >
+class SkTHashCache : public SkNoncopyable {
+public:
+
+    SkTHashCache() {

[mtklein, 2014/07/11 17:08:08]

Consider this:

SkTHashCache {
  this->reset();
}

~SkTHashCache {
  this->clear();
}

void reset() {
  this->clear();
  fDict.reset(SkNEW(DictType));
}

private:

void clear() {
  if (fDict.get()) { .... }
}

[Rémi Piotaix, 2014/07/11 17:45:00]

Done.

+        this->clear();
+    }
+
+    ~SkTHashCache() {
+        fValues.deleteAll();

[mtklein, 2014/07/11 17:08:08]

Looks like we leak the last values?

[Rémi Piotaix, 2014/07/11 17:45:01]

I'm sorry, I don't understand your question.

+    }
+
+    bool has(const Key& key) const {
+        return NULL != this->find(key);
+    }
+
+    T* find(const Key& key) const {
+        return fDict->find(key);
+    }
+
+    /**
+     *  If element already in cache, return immediately the cached value
+     */
+    T& add(T& add) {

[mtklein, 2014/07/11 17:08:08]

Looks like argument to add can be const&?

[Rémi Piotaix, 2014/07/11 17:45:01]

Done.

+        Key key = Traits::GetKey(add);
+        if (T * val = this->find(key)) {

[mtklein, 2014/07/11 17:08:08]

stray space before *?

[Rémi Piotaix, 2014/07/11 17:45:01]

Done.

+            return *val;
+        }
+
+        T* element = new T(add);

[mtklein, 2014/07/11 17:08:08]

SkNEW

[Rémi Piotaix, 2014/07/11 17:45:00]

Done.

+
+        fDict->add(element);
+
+        return *element;
+    }
+
+    int size() const {
+        return fDict->count();
+    }
+
+    void clear() {
+        if (fDict.get()) {
+            typename DictType::Iter it(fDict.get());
+
+            while (!it.done()) {
+                delete &(*it);

[mtklein, 2014/07/11 17:08:08]

SkDELETE

[Rémi Piotaix, 2014/07/11 17:45:01]

Done.

+                ++it;
+            }
+        }
+
+        fDict.reset(SkNEW(DictType));
+    }
+
+private:
+    typedef SkTDynamicHash<T, Key, Traits, kGrowPercent> DictType;
+
+    SkAutoTDelete<DictType> fDict;
+    SkTDArray<T*> fValues;
+};
+
+#endif	/* SkHASHCACHE_DEFINED */
+