gecko/modules/libpr0n/decoders/nsBMPDecoder.h

226 lines
7.3 KiB
C++

/* vim:set tw=80 expandtab softtabstop=4 ts=4 sw=4: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Mozilla BMP Decoder.
*
* The Initial Developer of the Original Code is
* Christian Biesinger <cbiesinger@web.de>.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Bobby Holley <bobbyholley@gmail.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef _nsBMPDecoder_h
#define _nsBMPDecoder_h
#include "nsAutoPtr.h"
#include "imgIDecoderObserver.h"
#include "gfxColor.h"
#include "Decoder.h"
namespace mozilla {
namespace imagelib {
struct BMPFILEHEADER {
char signature[2]; // String "BM"
PRUint32 filesize;
PRInt32 reserved; // Zero
PRUint32 dataoffset; // Offset to raster data
PRUint32 bihsize;
};
#define BFH_LENGTH 18 // Note: For our purposes, we include bihsize in the BFH
#define OS2_BIH_LENGTH 12 // This is the real BIH size (as contained in the bihsize field of BMPFILEHEADER)
#define OS2_HEADER_LENGTH (BFH_LENGTH + 8)
#define WIN_HEADER_LENGTH (BFH_LENGTH + 36)
struct BMPINFOHEADER {
PRInt32 width; // Uint16 in OS/2 BMPs
PRInt32 height; // Uint16 in OS/2 BMPs
PRUint16 planes; // =1
PRUint16 bpp; // Bits per pixel.
// The rest of the header is not available in OS/2 BMP Files
PRUint32 compression; // 0=no compression 1=8bit RLE 2=4bit RLE
PRUint32 image_size; // (compressed) image size. Can be 0 if compression==0
PRUint32 xppm; // Pixels per meter, horizontal
PRUint32 yppm; // Pixels per meter, vertical
PRUint32 colors; // Used Colors
PRUint32 important_colors; // Number of important colors. 0=all
};
struct colorTable {
PRUint8 red;
PRUint8 green;
PRUint8 blue;
};
struct bitFields {
PRUint32 red;
PRUint32 green;
PRUint32 blue;
PRUint8 redLeftShift;
PRUint8 redRightShift;
PRUint8 greenLeftShift;
PRUint8 greenRightShift;
PRUint8 blueLeftShift;
PRUint8 blueRightShift;
};
#define BITFIELD_LENGTH 12 // Length of the bitfields structure in the bmp file
#if defined WORDS_BIGENDIAN || defined IS_BIG_ENDIAN
// We must ensure that the entity is unsigned
// otherwise, if it is signed/negative, the MSB will be
// propagated when we shift
#define LITTLE_TO_NATIVE16(x) (((((PRUint16) x) & 0xFF) << 8) | \
(((PRUint16) x) >> 8))
#define LITTLE_TO_NATIVE32(x) (((((PRUint32) x) & 0xFF) << 24) | \
(((((PRUint32) x) >> 8) & 0xFF) << 16) | \
(((((PRUint32) x) >> 16) & 0xFF) << 8) | \
(((PRUint32) x) >> 24))
#else
#define LITTLE_TO_NATIVE16(x) x
#define LITTLE_TO_NATIVE32(x) x
#endif
#define USE_RGB
// BMPINFOHEADER.compression defines
#define BI_RLE8 1
#define BI_RLE4 2
#define BI_BITFIELDS 3
// RLE Escape codes
#define RLE_ESCAPE 0
#define RLE_ESCAPE_EOL 0
#define RLE_ESCAPE_EOF 1
#define RLE_ESCAPE_DELTA 2
/// enums for mState
enum ERLEState {
eRLEStateInitial,
eRLEStateNeedSecondEscapeByte,
eRLEStateNeedXDelta,
eRLEStateNeedYDelta, ///< mStateData will hold x delta
eRLEStateAbsoluteMode, ///< mStateData will hold count of existing data to read
eRLEStateAbsoluteModePadded ///< As above, but another byte of data has to be read as padding
};
class RasterImage;
/**
* Decoder for BMP-Files, as used by Windows and OS/2
*/
class nsBMPDecoder : public Decoder
{
public:
nsBMPDecoder();
~nsBMPDecoder();
virtual void WriteInternal(const char* aBuffer, PRUint32 aCount);
virtual void FinishInternal();
private:
/** Calculates the red-, green- and blueshift in mBitFields using
* the bitmasks from mBitFields */
NS_METHOD CalcBitShift();
PRUint32 mPos;
BMPFILEHEADER mBFH;
BMPINFOHEADER mBIH;
char mRawBuf[36];
PRUint32 mLOH; ///< Length of the header
PRUint32 mNumColors; ///< The number of used colors, i.e. the number of entries in mColors
colorTable *mColors;
bitFields mBitFields;
PRUint32 *mImageData; ///< Pointer to the image data for the frame
PRUint8 *mRow; ///< Holds one raw line of the image
PRUint32 mRowBytes; ///< How many bytes of the row were already received
PRInt32 mCurLine; ///< Index of the line of the image that's currently being decoded
PRInt32 mOldLine; ///< Previous index of the line
PRInt32 mCurPos; ///< Index in the current line of the image
ERLEState mState; ///< Maintains the current state of the RLE decoding
PRUint32 mStateData;///< Decoding information that is needed depending on mState
/** Set mBFH from the raw data in mRawBuf, converting from little-endian
* data to native data as necessary */
void ProcessFileHeader();
/** Set mBIH from the raw data in mRawBuf, converting from little-endian
* data to native data as necessary */
void ProcessInfoHeader();
};
/** Sets the pixel data in aDecoded to the given values.
* @param aDecoded pointer to pixel to be set, will be incremented to point to the next pixel.
*/
static inline void SetPixel(PRUint32*& aDecoded, PRUint8 aRed, PRUint8 aGreen, PRUint8 aBlue, PRUint8 aAlpha = 0xFF)
{
*aDecoded++ = GFX_PACKED_PIXEL(aAlpha, aRed, aGreen, aBlue);
}
static inline void SetPixel(PRUint32*& aDecoded, PRUint8 idx, colorTable* aColors)
{
SetPixel(aDecoded, aColors[idx].red, aColors[idx].green, aColors[idx].blue);
}
/** Sets two (or one if aCount = 1) pixels
* @param aDecoded where the data is stored. Will be moved 4 resp 8 bytes
* depending on whether one or two pixels are written.
* @param aData The values for the two pixels
* @param aCount Current count. Is decremented by one or two.
*/
inline void Set4BitPixel(PRUint32*& aDecoded, PRUint8 aData,
PRUint32& aCount, colorTable* aColors)
{
PRUint8 idx = aData >> 4;
SetPixel(aDecoded, idx, aColors);
if (--aCount > 0) {
idx = aData & 0xF;
SetPixel(aDecoded, idx, aColors);
--aCount;
}
}
} // namespace imagelib
} // namespace mozilla
#endif