Split SkBmpCodec into three separate classes

src/codec/SkBmpStandardCodec.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 "SkBmpCodec.h"
+#include "SkColorTable.h"
+#include "SkImageInfo.h"
+#include "SkSwizzler.h"
+#include "SkTypes.h"
+
+/*
+ * This class implements the decoding for bmp images that use "standard" modes,
+ * which essentially means they do not contain bit masks or RLE codes.
+ */
+class SkBmpStandardCodec : public SkBmpCodec {
+public:
+
+    /*
+     * Creates an instance of the decoder
+     * Called only by SkBmpCodec::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 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

[scroggo, 2015/08/04 16:16:47]

@param isIco Whether this is part of an ICO image. (Maybe inIco is more
appropriate?)

[msarett, 2015/08/04 23:14:45]

Agreed

+     */
+    SkBmpStandardCodec(const SkImageInfo& srcInfo, SkStream* stream,
+               uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor,
+               uint32_t offset, SkBmpCodec::RowOrder rowOrder, bool isIco);
+
+protected:
+
+    Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
+                       size_t dstRowBytes, const Options&, SkPMColor*,
+                       int*) override;
+
+private:
+
+    /*
+     * Creates the color table
+     * Sets colorCount to the new color count if it is non-NULL
+     */
+    bool createColorTable(SkAlphaType alphaType, int* colorCount);

[msarett, 2015/08/03 22:52:36]

Used to be in SkBmpCodec.  Simplified given that we know that we are not in RLE
mode.

+
+    bool initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts);

[msarett, 2015/08/03 22:52:36]

Factored out of decode() in SkBmpCodec.  Will be useful for scanline decoding.

+
+    Result decode(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options& opts);

[msarett, 2015/08/03 22:52:36]

Used to be decode() in SkBmpCodec.

+
+    SkAutoTUnref<SkColorTable>          fColorTable;     // owned
+    uint32_t                            fNumColors;
+    const uint32_t                      fBytesPerColor;
+    const uint32_t                      fOffset;
+    SkAutoTDelete<SkSwizzler>           fSwizzler;
+    SkAutoTDeleteArray<uint8_t>         fSrcBuffer;
+    const bool                          fIsIco;

[scroggo, 2015/08/04 16:16:47]

So, if I understand correctly, only standard BMPs can be in ICO?

[msarett, 2015/08/04 23:14:45]

You understand correctly.  I will add checks for this and comments in
ReadHeader.

+    bool                                fIsTransparent;
+
+    typedef SkBmpCodec INHERITED;
+};