/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef mozilla_image_decoders_nsBMPDecoder_h #define mozilla_image_decoders_nsBMPDecoder_h #include "BMPHeaders.h" #include "Decoder.h" #include "gfxColor.h" #include "StreamingLexer.h" #include "mozilla/UniquePtr.h" namespace mozilla { namespace image { namespace bmp { /// This struct contains the fields from the file header and info header that /// we use during decoding. (Excluding bitfields fields, which are kept in /// BitFields.) struct Header { uint32_t mDataOffset; // Offset to raster data. uint32_t mBIHSize; // Header size. int32_t mWidth; // Image width. int32_t mHeight; // Image height. uint16_t mBpp; // Bits per pixel. uint32_t mCompression; // See struct Compression for valid values. uint32_t mImageSize; // (compressed) image size. Can be 0 if // mCompression==0. uint32_t mNumColors; // Used colors. Header() : mDataOffset(0) , mBIHSize(0) , mWidth(0) , mHeight(0) , mBpp(0) , mCompression(0) , mImageSize(0) , mNumColors(0) {} }; /// An entry in the color table. struct ColorTableEntry { uint8_t mRed; uint8_t mGreen; uint8_t mBlue; }; /// All the color-related bitfields for 16bpp and 32bpp images. We use this /// even for older format BMPs that don't have explicit bitfields. class BitFields { class Value { friend class BitFields; uint32_t mMask; // The mask for the value. uint8_t mRightShift; // The amount to right-shift after masking. uint8_t mBitWidth; // The width (in bits) of the value. /// Sets the mask (and thus the right-shift and bit-width as well). void Set(uint32_t aMask); public: Value() { mMask = 0; mRightShift = 0; mBitWidth = 0; } /// Returns true if this channel is used. Only used for alpha. bool IsPresent() const { return mMask != 0x0; } /// Extracts the single color value from the multi-color value. uint8_t Get(uint32_t aVal) const; /// Like Get(), but specially for alpha. uint8_t GetAlpha(uint32_t aVal, bool& aHasAlphaOut) const; /// Specialized versions of Get() for when the bit-width is 5 or 8. /// (They will assert if called and the bit-width is not 5 or 8.) uint8_t Get5(uint32_t aVal) const; uint8_t Get8(uint32_t aVal) const; }; public: /// The individual color channels. Value mRed; Value mGreen; Value mBlue; Value mAlpha; /// Set bitfields to the standard 5-5-5 16bpp values. void SetR5G5B5(); /// Set bitfields to the standard 8-8-8 32bpp values. void SetR8G8B8(); /// Test if bitfields have the standard 5-5-5 16bpp values. bool IsR5G5B5() const; /// Test if bitfields have the standard 8-8-8 32bpp values. bool IsR8G8B8() const; /// Read the bitfields from a header. The reading of the alpha mask is /// optional. void ReadFromHeader(const char* aData, bool aReadAlpha); /// Length of the bitfields structure in the BMP file. static const size_t LENGTH = 12; }; } // namespace bmp class RasterImage; /// Decoder for BMP-Files, as used by Windows and OS/2. class nsBMPDecoder : public Decoder { public: ~nsBMPDecoder(); /// Obtains the internal output image buffer. uint32_t* GetImageData() { return reinterpret_cast<uint32_t*>(mImageData); } /// Obtains the length of the internal output image buffer. size_t GetImageDataLength() const { return mImageDataLength; } /// Obtains the size of the compressed image resource. int32_t GetCompressedImageSize() const; /// Mark this BMP as being within an ICO file. Only used for testing purposes /// because the ICO-specific constructor does this marking automatically. void SetIsWithinICO() { mIsWithinICO = true; } /// Did the BMP file have alpha data of any kind? (Only use this after the /// bitmap has been fully decoded.) bool HasTransparency() const { return mDoesHaveTransparency; } LexerResult DoDecode(SourceBufferIterator& aIterator, IResumable* aOnResume) override; nsresult BeforeFinishInternal() override; nsresult FinishInternal() override; private: friend class DecoderFactory; enum class State { FILE_HEADER, INFO_HEADER_SIZE, INFO_HEADER_REST, BITFIELDS, COLOR_TABLE, GAP, AFTER_GAP, PIXEL_ROW, RLE_SEGMENT, RLE_DELTA, RLE_ABSOLUTE }; // This is the constructor used for normal BMP images. explicit nsBMPDecoder(RasterImage* aImage); // This is the constructor used for BMP resources in ICO images. nsBMPDecoder(RasterImage* aImage, uint32_t aDataOffset); // Helper constructor called by the other two. nsBMPDecoder(RasterImage* aImage, State aState, size_t aLength); int32_t AbsoluteHeight() const { return abs(mH.mHeight); } uint32_t* RowBuffer(); void FinishRow(); LexerTransition<State> ReadFileHeader(const char* aData, size_t aLength); LexerTransition<State> ReadInfoHeaderSize(const char* aData, size_t aLength); LexerTransition<State> ReadInfoHeaderRest(const char* aData, size_t aLength); LexerTransition<State> ReadBitfields(const char* aData, size_t aLength); LexerTransition<State> ReadColorTable(const char* aData, size_t aLength); LexerTransition<State> SkipGap(); LexerTransition<State> AfterGap(); LexerTransition<State> ReadPixelRow(const char* aData); LexerTransition<State> ReadRLESegment(const char* aData); LexerTransition<State> ReadRLEDelta(const char* aData); LexerTransition<State> ReadRLEAbsolute(const char* aData, size_t aLength); StreamingLexer<State> mLexer; bmp::Header mH; // If the BMP is within an ICO file our treatment of it differs slightly. bool mIsWithinICO; bmp::BitFields mBitFields; // Might the image have transparency? Determined from the headers during // metadata decode. (Does not guarantee the image actually has transparency.) bool mMayHaveTransparency; // Does the image have transparency? Determined during full decoding, so only // use this after that has been completed. bool mDoesHaveTransparency; uint32_t mNumColors; // The number of used colors, i.e. the number of // entries in mColors, if it's present. UniquePtr<bmp::ColorTableEntry[]> mColors; // The color table, if it's present. uint32_t mBytesPerColor; // 3 or 4, depending on the format // The number of bytes prior to the optional gap that have been read. This // is used to find the start of the pixel data. uint32_t mPreGapLength; uint32_t mPixelRowSize; // The number of bytes per pixel row. int32_t mCurrentRow; // Index of the row of the image that's currently // being decoded: [height,1]. int32_t mCurrentPos; // Index into the current line. Used when // doing RLE decoding and when filling in pixels // for truncated files. // Only used in RLE_ABSOLUTE state: the number of pixels to read. uint32_t mAbsoluteModeNumPixels; }; } // namespace image } // namespace mozilla #endif // mozilla_image_decoders_nsBMPDecoder_h