Add SkImageGenerator Interface

src/core/SkBasicDiscardableMemory.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 "SkBasicDiscardableMemory.h"
+#include "SkTypes.h"
+
+SkDiscardableMemory* SkBasicDiscardableMemory::Create(size_t bytes) {
+    void* ptr = sk_malloc_throw(bytes);
+    if (NULL == ptr) {
+        return NULL;
+    }
+    return SkNEW_ARGS(SkBasicDiscardableMemory, (ptr));
+}
+
+SkBasicDiscardableMemory::SkBasicDiscardableMemory(void* ptr)
+    : fLocked(true)
+    , fPointer(ptr) {
+    SkASSERT(fPointer != NULL);
+}
+
+SkBasicDiscardableMemory::~SkBasicDiscardableMemory() {
+    SkASSERT(!fLocked);
+    sk_free(fPointer);
+}
+
+bool SkBasicDiscardableMemory::lock() {
+    SkASSERT(!fLocked);
+    return fLocked = true;
+}
+
+void* SkBasicDiscardableMemory::data() {
+    SkASSERT(fLocked);
+    return fPointer;

[scroggo, 2013/11/19 22:19:27]

Should this return NULL if not locked?

[hal.canary, 2013/11/20 00:07:10]

Should we allow the caller to make that mistake?  In Release, I'll put the extra
check in place and return NULL.

Done.

+}
+
+void SkBasicDiscardableMemory::unlock() {
+    SkASSERT(fLocked);
+    fLocked = false;    
+}