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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_PALETTE_H
#define GRAPHICS_PALETTE_H
#include "common/noncopyable.h"
/**
* The PaletteManager is part of the OSystem backend API and responsible
* for handling the (possibly emulated) "hardware" palette needed for
* many old games (e.g. in EGA and VGA mode).
*
* By itself it is a pure abstract class, i.e. an "interface"; you can
* use the OSystem::getPaletteManager() method to obtain an instance
* that you can use to perform actual palette modifications.
*/
class PaletteManager : Common::NonCopyable {
public:
virtual ~PaletteManager() {}
/**
* Replace the specified range of the palette with new colors.
* The palette entries from 'start' till (start+num-1) will be replaced - so
* a full palette update is accomplished via start=0, num=256.
*
* The palette data is specified in interleaved RGBA format. That is, the
* first byte of the memory block 'colors' points at is the red component
* of the first new color; the second byte the green component of the first
* new color; the third byte the blue component, the last byte to the alpha
* (transparency) value. Then the second color starts, and so on. So memory
* looks like this: R1-G1-B1-A1-R2-G2-B2-A2-R3-...
*
* @param colors the new palette data, in interleaved RGBA format
* @param start the first palette entry to be updated
* @param num the number of palette entries to be updated
*
* @note It is an error if start+num exceeds 256, behaviour is undefined
* in that case (the backend may ignore it silently or assert).
* @note It is an error if this function gets called when the pixel format
* in use (the return value of getScreenFormat) has more than one
* byte per pixel.
* @note The alpha value is not actually used, and future revisions of this
* API are probably going to remove it.
*
* @see getScreenFormat
*/
virtual void setPalette(const byte *colors, uint start, uint num) = 0;
/**
* Grabs a specified part of the currently active palette.
* The format is the same as for setPalette.
*
* This should return exactly the same RGB data as was setup via previous
* setPalette calls.
*
* For example, for every valid value of start and num of the following
* code:
*
* byte origPal[num*4];
* // Setup origPal's data however you like
* g_system->setPalette(origPal, start, num);
* byte obtainedPal[num*4];
* g_system->grabPalette(obtainedPal, start, num);
*
* the following should be true:
*
* For each i < num : memcmp(&origPal[i*4], &obtainedPal[i*4], 3) == 0
* (i is an uint here)
*
* @see setPalette
* @param colors the palette data, in interleaved RGBA format
* @param start the first platte entry to be read
* @param num the number of palette entries to be read
*
* @note It is an error if this function gets called when the pixel format
* in use (the return value of getScreenFormat) has more than one
* byte per pixel.
*
* @see getScreenFormat
*/
virtual void grabPalette(byte *colors, uint start, uint num) = 0;
};
#endif
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