Add SkImageGenerator Interface

-   Add SkDiscardablePixelRef class that uses SkDiscardableMemory and
    a SkImageGenerator.

-   Add SkDecodingImageGenerator class as an example of a
    SkImageGenerator.

-   Add DecodingImageGenerator unit test.

-   Add SkBasicDiscardableMemory implmentation for unit tests only.

R=reed@google.com, scroggo@google.com

Review URL: https://codereview.chromium.org/74793011

git-svn-id: http://skia.googlecode.com/svn/trunk@12341 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 50 insertions, 1 deletions

diff --git a/src/ports/SkDiscardableMemory_none.cpp b/src/ports/SkDiscardableMemory_none.cpp
index 6559097e62..700713ba48 100644
--- a/src/ports/SkDiscardableMemory_none.cpp
+++ b/src/ports/SkDiscardableMemory_none.cpp
@@ -6,7 +6,56 @@
  */
 
 #include "SkDiscardableMemory.h"
+#include "SkTypes.h"
+
+namespace {
+////////////////////////////////////////////////////////////////////////////////
+/**
+ *  Always successful, never purges.  Useful for testing.
+ */
+class SkMockDiscardableMemory : public SkDiscardableMemory {
+public:
+    SkMockDiscardableMemory(void*);
+    virtual ~SkMockDiscardableMemory();
+    virtual bool lock() SK_OVERRIDE;
+    virtual void* data() SK_OVERRIDE;
+    virtual void unlock() SK_OVERRIDE;
+private:
+    bool fLocked;
+    void* fPointer;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+SkMockDiscardableMemory::SkMockDiscardableMemory(void* ptr)
+    : fLocked(true)
+    , fPointer(ptr) {  // Takes ownership of ptr.
+    SkASSERT(fPointer != NULL);
+}
+
+SkMockDiscardableMemory::~SkMockDiscardableMemory() {
+    SkASSERT(!fLocked);
+    sk_free(fPointer);
+}
+
+bool SkMockDiscardableMemory::lock() {
+    SkASSERT(!fLocked);
+    return fLocked = true;
+}
+
+void* SkMockDiscardableMemory::data() {
+    SkASSERT(fLocked);
+    return fLocked ? fPointer : NULL;
+}
+
+void SkMockDiscardableMemory::unlock() {
+    SkASSERT(fLocked);
+    fLocked = false;
+}
+////////////////////////////////////////////////////////////////////////////////
+}  // namespace
 
 SkDiscardableMemory* SkDiscardableMemory::Create(size_t bytes) {
-    return NULL;
+    void* ptr = sk_malloc_throw(bytes);
+    return (ptr != NULL) ? SkNEW_ARGS(SkMockDiscardableMemory, (ptr)) : NULL;
 }