Bmp Image Decoding

src/codec/SkCodec_libbmp.h

+/*
+ * 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 "SkImageInfo.h"
+#include "SkStream.h"
+#include "SkTypes.h"
+
+#ifdef SK_SUPPORT_LEGACY_IMAGE_GENERATOR_RETURN
+    #define onGetPixels onGetPixelsEnum
+#endif
+
+/*
+ * 
+ * This class implements the decoding for bitmap images
+ *
+ */
+class SkBmpCodec : public SkCodec {
+public:
+
+    /*
+     *
+     * Checks the start of the stream to see if the image is a bitmap
+     *
+     */
+    static bool IsBmp(SkStream*);
+    
+    /*
+     * 
+     * Assumes IsBmp was called and returned true
+     * Creates a bitmap decoder
+     * Reads enough of the stream to determine the image format
+     *
+     */
+    static SkCodec* NewFromStream(SkStream*);
+    
+protected:
+
+    /*
+     *
+     * Initiates the bitmap decode
+     *
+     */
+    virtual Result onGetPixels(const SkImageInfo&, void*, size_t, SkPMColor*,
+            int*) SK_OVERRIDE;
+private:
+
+    /*
+     *
+     * Used to define the inout format of the bitmap
+     *
+     */
+    enum BitmapInputFormat {
+        kStandard_BitmapInputFormat,
+        k4BitRLE_BitmapInputFormat,
+        k8BitRLE_BitmapInputFormat,
+        kBitMask_BitmapInputFormat,
+        kUnknown_BitmapInputFormat
+    };
+
+    /*
+     *
+     * Performs the bitmap decoding for standard and bit masks input format
+     *
+     */
+    Result decode(const SkImageInfo&, void*, uint32_t);
+    
+    /*
+     *
+     * Creates an instance of the decoder
+     * Called only by NewFromStream
+     *
+     */
+    SkBmpCodec(const SkImageInfo&, SkStream*, const uint16_t,
+               const BitmapInputFormat, uint32_t*, SkPMColor*, const bool);
+
+    /*
+     *
+     * Clean up memory used by the decoder
+     *
+     */
+    ~SkBmpCodec();
+    
+    // Constants
+    static const int kBmpHeaderBytes = 14;
+    static const int kBmpOS2V1Bytes =  12;
+    static const int kBmpOS2V2Bytes =  64;
+    static const int kBmpInfoV1Bytes = 40;
+    static const int kBmpInfoV2Bytes = 52;
+    static const int kBmpInfoV3Bytes = 56;
+    static const int kBmpInfoV4Bytes = 108;
+    static const int kBmpInfoV5Bytes = 124;
+    static const int kBmpMaskBytes =   12;
+    static const int kBmpMaxDim =      1 << 16;
+
+    const uint16_t                 fBitsPerPixel;
+    const BitmapInputFormat        fInputFormat;
+    const SkAutoTDelete<uint32_t>  fBitMasks;
+    const SkAutoTDelete<SkPMColor> fColorTable;
+    const bool fInverted;
+    
+    typedef SkCodec INHERITED;
+};