Split SkBmpCodec into three separate classes

src/codec/SkBmpCodec.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.
  */
+#ifndef SkBmpCodec_DEFINED
+#define SkBmpCodec_DEFINED
 
 #include "SkCodec.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
 #include "SkMaskSwizzler.h"
 #include "SkStream.h"
 #include "SkSwizzler.h"
 #include "SkTypes.h"
 
-// TODO: rename SkCodec_libbmp files to SkBmpCodec
 /*
- *
- * This class implements the decoding for bmp images
- *
+ * This class enables the creation of specific bmp codecs that subclass SkCodec
  */
-class SkBmpCodec : public SkCodec {
+class SkBmpCodec {
 public:
 
     /*
-     *
      * Describes if rows of the input start at the top or bottom of the image
-     *
      */
     enum RowOrder {
         kTopDown_RowOrder,
         kBottomUp_RowOrder
     };
 
     /*
-     *
      * Checks the start of the stream to see if the image is a bmp
-     *
      */
     static bool IsBmp(SkStream*);
 
     /*
-     *
      * Assumes IsBmp was called and returned true
      * Creates a bmp decoder
      * Reads enough of the stream to determine the image format
-     *
      */
     static SkCodec* NewFromStream(SkStream*);
 
     /*
-     *
      * Creates a bmp decoder for a bmp embedded in ico
      * Reads enough of the stream to determine the image format
-     *
      */
     static SkCodec* NewFromIco(SkStream*);
 
-protected:
-
-    /*
-     *
-     * Initiates the bmp decode
-     *
-     */
-    Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
-                       size_t dstRowBytes, const Options&, SkPMColor*,
-                       int*) override;
-
-    SkEncodedFormat onGetEncodedFormat() const override { return kBMP_SkEncodedFormat; }
-
 private:
 
     /*
-     *
      * Used to define the input format of the bmp
-     *
      */
-    enum BitmapInputFormat {
-        kStandard_BitmapInputFormat,
-        kRLE_BitmapInputFormat,
-        kBitMask_BitmapInputFormat,
-        kUnknown_BitmapInputFormat
+    enum BmpInputFormat {
+        kStandard_BmpInputFormat,
+        kRLE_BmpInputFormat,
+        kBitMask_BmpInputFormat,
+        kUnknown_BmpInputFormat
     };
 
     /*
-     *
-     * Creates the color table
-     * Sets colorCount to the new color count if it is non-NULL
-     */
-     bool createColorTable(SkAlphaType alphaType, int* colorCount);
-
-    /*
-     *
      * Creates a bmp decoder
      * Reads enough of the stream to determine the image format
-     *
      */
     static SkCodec* NewFromStream(SkStream*, bool isIco);
 
     /*
-     *
      * Read enough of the stream to initialize the SkBmpCodec. Returns a bool
      * representing success or failure. If it returned true, and codecOut was
      * not NULL, it will be set to a new SkBmpCodec.
      * Does *not* take ownership of the passed in SkStream.
-     *
      */
     static bool ReadHeader(SkStream*, bool isIco, SkCodec** codecOut);
 
     /*
-     *
-     * Performs the bitmap decoding for bit masks input format
-     *
+     * Fix the decoded output when a bmp is encoded as fully transparent.
+     * It was most likely not intended to be opaque.
      */
-    Result decodeMask(const SkImageInfo& dstInfo, void* dst,
-                      size_t dstRowBytes, const Options& opts);
+    static SkCodec::Result FixTransparentDecode(void* dst, size_t dstRowBytes,
+            SkPMColor* colorPtr, int* colorCountPtr, SkStream* stream);
 
-    /*
-     *
-     * Set an RLE pixel using the color table
-     *
-     */
-    void setRLEPixel(void* dst, size_t dstRowBytes,
-                     const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
-                     uint8_t index);
-    /*
-     *
-     * Set an RLE24 pixel from R, G, B values
-     *
-     */
-    void setRLE24Pixel(void* dst, size_t dstRowBytes,
-                       const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
-                       uint8_t red, uint8_t green, uint8_t blue);
+    friend class SkBmpMaskCodec;
+    friend class SkBmpRLECodec;
+    friend class SkBmpStandardCodec;
+};
 
-    /*
-     *
-     * Performs the bitmap decoding for RLE input format
-     *
-     */
-    Result decodeRLE(const SkImageInfo& dstInfo, void* dst,
-                     size_t dstRowBytes, const Options& opts);
-
-    /*
-     *
-     * Performs the bitmap decoding for standard input format
-     *
-     */
-    Result decode(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options& opts);
-
-    /*
-     *
-     * Creates an instance of the decoder
-     * Called only by NewFromStream
-     *
-     * @param srcInfo contains the source width and height
-     * @param stream the stream of image data
-     * @param bitsPerPixel the number of bits used to store each pixel
-     * @param format the format of the bmp file
-     * @param masks optional color masks for certain bmp formats, passes
-                    ownership to SkBmpCodec
-     * @param numColors the number of colors in the color table
-     * @param bytesPerColor the number of bytes in the stream used to represent
-                            each color in the color table
-     * @param offset the offset of the image pixel data from the end of the
-     *               headers
-     * @param rowOrder indicates whether rows are ordered top-down or bottom-up
-     * @param RLEBytes used only for RLE decodes, as we must decode all
-     *                  of the data at once rather than row by row
-     *                  it indicates the amount of data left in the stream
-     *                  after decoding the headers
-     *
-     */
-    SkBmpCodec(const SkImageInfo& srcInfo, SkStream* stream,
-               uint16_t bitsPerPixel, BitmapInputFormat format,
-               SkMasks* masks, uint32_t numColors, uint32_t bytesPerColor,
-               uint32_t offset, RowOrder rowOrder, size_t RLEBytes,
-               bool isIco);
-
-    // Fields
-    const uint16_t                      fBitsPerPixel;
-    const BitmapInputFormat             fInputFormat;
-    SkAutoTDelete<SkMasks>              fMasks;          // owned
-    SkAutoTUnref<SkColorTable>          fColorTable;     // owned
-    uint32_t                            fNumColors;
-    const uint32_t                      fBytesPerColor;
-    const uint32_t                      fOffset;
-    const RowOrder                      fRowOrder;
-    const size_t                        fRLEBytes;
-    const bool                          fIsIco;
-
-    typedef SkCodec INHERITED;
-};
+#endif