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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*/
#ifndef GRAPHICS_DITHER_H
#define GRAPHICS_DITHER_H
#include "common/util.h"
#include "common/stream.h"
namespace Graphics {
/** A palette lookup table to find the nearest matching entry of a fixed palette to a true color.
*
* The table can be build up in slices, one slice consisting of all entries for
* one value of the first color component.
*/
class PaletteLUT {
public:
/** Palette format. */
enum PaletteFormat {
kPaletteRGB, //!< Palette in RGB colorspace
kPaletteYUV //!< Palette in YUV colorspace
};
/** Create a lookup table of a given depth and palette format.
*
* @param depth How many bits of each color component to consider.
* @param format The format the palette should be in.
*/
PaletteLUT(byte depth, PaletteFormat format);
~PaletteLUT();
/** Setting a palette.
*
* Any already built slices will be purged.
*
* @param palette The palette, plain 256 * 3 color components.
* @param format The format the palette is in.
* @param depth The number of significant bits in each color component.
* @param transp An index that's seen as transparent and therefore ignored.
*/
void setPalette(const byte *palette, PaletteFormat format, byte depth, int transp = -1);
/** Build the next slice.
*
* This will build the next slice, if any.
*/
void buildNext();
/** Querying the color components to a given palette entry index. */
void getEntry(byte index, byte &c1, byte &c2, byte &c3) const;
/** Finding the nearest matching entry.
*
* @param c1 The first component of the wanted color.
* @param c2 The second component of the wanted color.
* @param c3 The third component of the wanted color.
* @return The palette entry matching the wanted color best.
*/
byte findNearest(byte c1, byte c2, byte c3);
/** Finding the nearest matching entry, together with its color components.
*
* @param c1 The first component of the wanted color.
* @param c2 The second component of the wanted color.
* @param c3 The third component of the wanted color.
* @paran nC1 The first component of the found color.
* @paran nC2 The second component of the found color.
* @paran nC3 The third component of the found color.
* @return The palette entry matching the wanted color best.
*/
byte findNearest(byte c1, byte c2, byte c3, byte &nC1, byte &nC2, byte &nC3);
/** Save the table to a stream.
*
* This will build the whole table first.
*/
bool save(Common::WriteStream &stream);
/** Load the table from a stream. */
bool load(Common::SeekableReadStream &stream);
private:
static const uint32 kVersion = 1;
byte _depth1; //!< The table's depth for one dimension.
byte _depth2; //!< The table's depth for two dimensions.
byte _shift; //!< Amount to shift to adjust for the table's depth.
uint32 _dim1; //!< The table's entry offset for one dimension.
uint32 _dim2; //!< The table's entry offset for two dimensions.
uint32 _dim3; //!< The table's entry offset for three dimensions.
int _transp; //!< The transparent palette index.
PaletteFormat _format; //!< The table's palette format.
byte _lutPal[768]; //!< The palette used for looking up a color.
byte _realPal[768]; //!< The original palette.
uint32 _got; //!< Number of slices generated.
byte *_gots; //!< Map of generated slices.
byte *_lut; //!< The lookup table.
/** Building a specified slice. */
void build(int d1);
/** Calculates the index into the lookup table for a given color. */
inline int getIndex(byte c1, byte c2, byte c3) const;
};
/** The Sierra-2-4A ("Filter Light") error distribution dithering algorithm.
*
* The image will be dithered line by line and pixel by pixel, without earlier
* values having to be changed.
*/
class SierraLight {
public:
/** Constructor.
*
* @param width The width of the image to dither.
* @param palLUT The palette to which to dither.
*/
SierraLight(int16 width, PaletteLUT *palLUT);
~SierraLight();
/** Signals that a new frame or image is about to be dithered.
*
* This clears all collected errors, so that a new image (of the same
* height and with the same palette) can be dithered.
*/
void newFrame();
/** Signals that a new line is about the begin.
*
* The current line's errors will be forgotten and values collected for the
* next line will now count as the current line's.
*/
void nextLine();
/** Dither a pixel.
*
* @param c1 The first color component of the pixel.
* @param c2 The second color component of the pixel.
* @param c3 The third color component of the pixel.
* @param x The pixel's x coordinate within the image.
*/
byte dither(byte c1, byte c2, byte c3, uint32 x);
protected:
int16 _width; //!< The image's width.
PaletteLUT *_palLUT; //!< The palette against which to dither.
int32 *_errorBuf; //!< Big buffer for all collected errors.
int32 *_errors[2]; //!< Pointers into the error buffer for two lines.
int _curLine; //!< Which one is the current line?
/** Querying a pixel's errors. */
inline void getErrors(uint32 x, int32 &eC1, int32 &eC2, int32 &eC3);
/** Adding a pixel's errors. */
inline void addErrors(uint32 x, int32 eC1, int32 eC2, int32 eC3);
};
} // End of namespace Graphics
#endif
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