path: root/src/utils/sdlpixel.h

/*
 *  The ManaPlus Client
 *  Copyright (C) 2011-2017  The ManaPlus Developers
 *
 *  This file is part of The ManaPlus Client.
 *
 *  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
 *  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, see <http://www.gnu.org/licenses/>.
 */

/*      _______   __   __  __   ______   __   __   _______   __   __
 *     / _____/\ / /\ / /\ / /\ / ____/\ / /\ / /\ / ___  /\ /  |\/ /\
 *    / /\____\// / // / // / // /\___\// /_// / // /\_/ / // , |/ / /
 *   / / /__   / / // / // / // / /    / ___  / // ___  / // /| ' / /
 *  / /_// /\ / /_// / // / // /_/_   / / // / // /\_/ / // / |  / /
 * /______/ //______/ //_/ //_____/\ /_/ //_/ //_/ //_/ //_/ /|_/ /
 * \______\/ \______\/ \_\/ \_____\/ \_\/ \_\/ \_\/ \_\/ \_\/ \_\/
 *
 * Copyright (c) 2004 - 2008 Olof Naessén and Per Larsson
 *
 *
 * Per Larsson a.k.a finalman
 * Olof Naessén a.k.a jansem/yakslem
 *
 * Visit: http://guichan.sourceforge.net
 *
 * License: (BSD)
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of Guichan nor the names of its contributors may
 *    be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef UTILS_SDLPIXEL_H
#define UTILS_SDLPIXEL_H

#include "gui/color.h"

#include <SDL.h>

#ifndef SDL_BYTEORDER
#error missing SDL_endian.h
#endif  // SDL_BYTEORDER

/**
  * Puts a pixel on an SDL_Surface.
  *
  * @param x the x coordinate on the surface.
  * @param y the y coordinate on the surface.
  * @param color the color the pixel should be in.
  */
inline void SDLputPixel(SDL_Surface* surface, int x, int y,
                        const Color& color)
{
    if (surface == nullptr)
        return;

    const int bpp = surface->format->BytesPerPixel;

    SDL_LockSurface(surface);

    Uint8 *const p = static_cast<uint8_t*>(surface->pixels)
        + CAST_SIZE(y * surface->pitch + x * bpp);

    const Uint32 pixel = SDL_MapRGB(surface->format,
        CAST_U8(color.r), CAST_U8(color.g),
        CAST_U8(color.b));

    switch (bpp)
    {
        case 1:
            *p = CAST_U8(pixel);
            break;

        case 2:
            *reinterpret_cast<uint16_t*>(p) = CAST_U16(pixel);
            break;

        case 3:
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
            p[0] = CAST_U8((pixel >> 16) & 0xff);
            p[1] = CAST_U8((pixel >> 8) & 0xff);
            p[2] = CAST_U8((pixel) & 0xff);
#else  // SDL_BYTEORDER == SDL_BIG_ENDIAN

            p[0] = CAST_U8((pixel) & 0xff);
            p[1] = CAST_U8((pixel >> 8) & 0xff);
            p[2] = CAST_U8((pixel >> 16) & 0xff);
#endif  // SDL_BYTEORDER == SDL_BIG_ENDIAN

            break;

        case 4:
            *reinterpret_cast<Uint32*>(p) = pixel;
            break;

        default:
            break;
    }

    SDL_UnlockSurface(surface);
}

/**
  * Blends two 32 bit colors together.
  *
  * @param src the source color.
  * @param dst the destination color.
  * @param a alpha.
  */
inline unsigned int SDLAlpha32(const unsigned int src,
                               const unsigned int dst,
                               const unsigned char a)
{
    const unsigned int b = ((src & 0xff) * a + (dst & 0xff) * (255 - a)) >> 8;
    const unsigned int g = ((src & 0xff00) * a + (dst & 0xff00)
        * (255 - a)) >> 8;
    const unsigned int r = ((src & 0xff0000) * a + (dst & 0xff0000)
        * (255 - a)) >> 8;

    return (b & 0xff) | (g & 0xff00) | (r & 0xff0000);
}

inline unsigned short SDLAlpha16(const unsigned short src,
                                 const unsigned short dst,
                                 const unsigned char a,
                                 const SDL_PixelFormat *const f) A_NONNULL(4);

/**
  * Blends two 16 bit colors together.
  *
  * @param src the source color.
  * @param dst the destination color.
  * @param a alpha.
  */
inline unsigned short SDLAlpha16(const unsigned short src,
                                 const unsigned short dst,
                                 const unsigned char a,
                                 const SDL_PixelFormat *const f)
{
    unsigned int b = ((src & f->Rmask) * a + (dst & f->Rmask)
        * (255 - a)) >> 8;
    unsigned int g = ((src & f->Gmask) * a + (dst & f->Gmask)
        * (255 - a)) >> 8;
    unsigned int r = ((src & f->Bmask) * a + (dst & f->Bmask)
        * (255 - a)) >> 8;

    return static_cast<unsigned short>((b & f->Rmask)
        | (g & f->Gmask) | (r & f->Bmask));
}

/**
  * Puts a pixel on an SDL_Surface with alpha
  *
  * @param x the x coordinate on the surface.
  * @param y the y coordinate on the surface.
  * @param color the color the pixel should be in.
  */
inline void SDLputPixelAlpha(SDL_Surface* surface, int x, int y,
                             const Color& color)
{
    if (surface == nullptr)
        return;
    const int bpp = surface->format->BytesPerPixel;

    SDL_LockSurface(surface);

    Uint8 *const p = static_cast<uint8_t*>(surface->pixels)
        + CAST_SIZE(y * surface->pitch + x * bpp);

    const Uint32 pixel = SDL_MapRGB(surface->format,
        CAST_U8(color.r),
        CAST_U8(color.g),
        CAST_U8(color.b));

    switch (bpp)
    {
        case 1:
            *p = CAST_U8(pixel);
            break;

        case 2:
            *reinterpret_cast<Uint16*>(p) = SDLAlpha16(
                static_cast<unsigned short>(pixel),
                *reinterpret_cast<unsigned short*>(p),
                CAST_U8(color.a), surface->format);
            break;

        case 3:
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
            p[2] = CAST_U8((p[2] * (255 - color.a)
                + color.b * color.a) >> 8);
            p[1] = CAST_U8((p[1] * (255 - color.a)
                + color.g * color.a) >> 8);
            p[0] = CAST_U8((p[0] * (255 - color.a)
                + color.r * color.a) >> 8);
#else  // SDL_BYTEORDER == SDL_BIG_ENDIAN

            p[0] = CAST_U8((p[0] * (255 - color.a)
                + color.b * color.a) >> 8);
            p[1] = CAST_U8((p[1] * (255 - color.a)
                + color.g * color.a) >> 8);
            p[2] = CAST_U8((p[2] * (255 - color.a)
                + color.r * color.a) >> 8);
#endif  // SDL_BYTEORDER == SDL_BIG_ENDIAN

            break;

        case 4:
            *reinterpret_cast<Uint32*>(p) = SDLAlpha32(pixel,
                *reinterpret_cast<Uint32*>(p),
                CAST_U8(color.a));
            break;
        default:
            break;
    }

    SDL_UnlockSurface(surface);
}

#endif  // UTILS_SDLPIXEL_H