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

2 files changed, 97 insertions, 0 deletions

diff --git a/src/images/SkDecodingImageGenerator.cpp b/src/images/SkDecodingImageGenerator.cpp
new file mode 100644
index 0000000000..65fa6fd561
--- /dev/null
+++ b/src/images/SkDecodingImageGenerator.cpp
@@ -0,0 +1,52 @@
+/*
+ * 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 "SkDecodingImageGenerator.h"
+
+#include "SkBitmapFactory.h"
+#include "SkData.h"
+#include "SkDiscardablePixelRef.h"
+#include "SkImageDecoder.h"
+
+SkDecodingImageGenerator::SkDecodingImageGenerator(SkData* data)
+    : fData(data) {
+    SkASSERT(fData != NULL);
+    fData->ref();
+}
+
+SkDecodingImageGenerator::~SkDecodingImageGenerator() {
+    fData->unref();
+}
+
+SkData* SkDecodingImageGenerator::refEncodedData() {
+    fData->ref();
+    return fData;
+}
+
+bool SkDecodingImageGenerator::getInfo(SkImageInfo* info) {
+    SkASSERT(info != NULL);
+    return SkImageDecoder::DecodeMemoryToTarget(fData->data(),
+                                                fData->size(),
+                                                info, NULL);
+}
+
+bool SkDecodingImageGenerator::getPixels(const SkImageInfo& info,
+                                         void* pixels,
+                                         size_t rowBytes) {
+    SkASSERT(pixels != NULL);
+    SkBitmapFactory::Target target = {pixels, rowBytes};
+    SkImageInfo tmpInfo = info;
+    return SkImageDecoder::DecodeMemoryToTarget(fData->data(),
+                                                fData->size(),
+                                                &tmpInfo, &target);
+}
+bool SkDecodingImageGenerator::Install(SkData* data, SkBitmap* dst) {
+    SkASSERT(data != NULL);
+    SkASSERT(dst != NULL);
+    SkImageGenerator* gen(SkNEW_ARGS(SkDecodingImageGenerator, (data)));
+    return SkDiscardablePixelRef::Install(gen, dst);
+}
diff --git a/src/images/SkDecodingImageGenerator.h b/src/images/SkDecodingImageGenerator.h
new file mode 100644
index 0000000000..682aeb619c
--- /dev/null
+++ b/src/images/SkDecodingImageGenerator.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDecodingImageGenerator_DEFINED
+#define SkDecodingImageGenerator_DEFINED
+
+#include "SkImageGenerator.h"
+
+class SkBitmap;
+
+/**
+ * Calls into SkImageDecoder::DecodeMemoryToTarget to implement a
+ * SkImageGenerator
+ */
+class SkDecodingImageGenerator : public SkImageGenerator {
+public:
+    /*
+     *  The constructor will take a reference to the SkData.  The
+     *  destructor will unref() it.
+     */
+    SkDecodingImageGenerator(SkData* data);
+    virtual ~SkDecodingImageGenerator();
+
+    virtual SkData* refEncodedData() SK_OVERRIDE;
+
+    virtual bool getInfo(SkImageInfo* info) SK_OVERRIDE;
+
+    virtual bool getPixels(const SkImageInfo& info,
+                           void* pixels,
+                           size_t rowBytes) SK_OVERRIDE;
+
+    /**
+     *  Install the SkData into the destination bitmap, using a new
+     *  SkDiscardablePixelRef and a new SkDecodingImageGenerator.
+     */
+    static bool Install(SkData* data, SkBitmap* destination);
+
+private:
+    SkData* fData;
+};
+#endif  // SkDecodingImageGenerator_DEFINED