Create an SkCodecImageGenerator

src/core/SkCodecImageGenerator.cpp

Index: src/core/SkCodecImageGenerator.cpp
diff --git a/src/core/SkCodecImageGenerator.cpp b/src/core/SkCodecImageGenerator.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..531f3b89393100ed3a835ff80019a109dfdb74c6
--- /dev/null
+++ b/src/core/SkCodecImageGenerator.cpp
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+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCodec.h"
+#include "SkImageGenerator.h"
+
+class SkCodecImageGenerator : SkImageGenerator {
+public:
+    /*
+     * Takes ownership of codec
+     */
+    static SkImageGenerator* Create(SkCodec* codec);
+
+protected:
+
+    bool onComputeScaledDimensions(SkScalar scale, SupportedSizes*) override;
+    bool onGenerateScaledPixels(const SkISize&, const SkIPoint&, const SkPixmap&) override;
+    bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, SkPMColor ctable[],
+            int* ctableCount) override;
+
+private:
+    SkCodecImageGenerator(SkCodec* codec);
+
+    SkAutoTDelete<SkCodec> fCodec; // Owned
+
+    typedef SkImageGenerator INHERITED;
+};
+
+SkImageGenerator* SkCodecImageGenerator::Create(SkCodec* codec) {
+    if (nullptr == codec) {
+        return nullptr;
+    }
+
+    return new SkCodecImageGenerator(codec);
+}
+
+SkImageGenerator* SkImageGenerator::NewFromEncodedImpl(SkData* data) {
+    return SkCodecImageGenerator::Create(SkCodec::NewFromData(data));
+}
+
+SkCodecImageGenerator::SkCodecImageGenerator(SkCodec* codec)
+    : INHERITED(codec->getInfo())
+    , fCodec(codec)
+{}
+
+bool SkCodecImageGenerator::onComputeScaledDimensions(SkScalar scale,
+                                                      SupportedSizes* sizes) {
+    const SkISize scaledSize = fCodec->getScaledDimensions(scale);
+    // FIXME: SkCodec should be able to suggest multiple scaled sizes.
+    sizes->fSizes[0] = scaledSize;
+    sizes->fSizes[1] = scaledSize;
+    return true;
+}
+
+bool SkCodecImageGenerator::onGenerateScaledPixels(const SkISize& scaledSize,
+                                                     const SkIPoint& scaledOrigin,
+                                                     const SkPixmap& scaledPixels) {
+    // FIXME: Subsets are not supported yet.
+    SkASSERT(scaledOrigin.isZero());
+    SkASSERT(scaledSize == scaledPixels.info().dimensions());
+
+    SkCodec::Result result = fCodec->getPixels(scaledPixels.info(), scaledPixels.writable_addr(),
+            scaledPixels.rowBytes());
+    switch (result) {
+        case SkCodec::kSuccess:
+        case SkCodec::kIncompleteInput:
+            return true;
+        default:
+            return false;
+    }
+}
+
+bool SkCodecImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
+                                        SkPMColor ctable[], int* ctableCount) {
+
+    SkCodec::Result result = fCodec->getPixels(info, pixels, rowBytes, nullptr, ctable,
+            ctableCount);
+    switch (result) {
+        case SkCodec::kSuccess:
+        case SkCodec::kIncompleteInput:
+            return true;
+        default:
+            return false;
+    }
+}