mmsfb_blit_blend_coloralpha_airgb_to_airgb.cpp

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/***************************************************************************
 *   Copyright (C) 2005-2007 Stefan Schwarzer, Jens Schneider,             *
 *                           Matthias Hardt, Guido Madaus                  *
 *                                                                         *
 *   Copyright (C) 2007-2008 BerLinux Solutions GbR                        *
 *                           Stefan Schwarzer & Guido Madaus               *
 *                                                                         *
 *   Copyright (C) 2009-2013 BerLinux Solutions GmbH                       *
 *                                                                         *
 *   Authors:                                                              *
 *      Stefan Schwarzer   <stefan.schwarzer@diskohq.org>,                 *
 *      Matthias Hardt     <matthias.hardt@diskohq.org>,                   *
 *      Jens Schneider     <jens.schneider@diskohq.org>,                   *
 *      Guido Madaus       <guido.madaus@diskohq.org>,                     *
 *      Patrick Helterhoff <patrick.helterhoff@diskohq.org>,               *
 *      René Bählkow       <rene.baehlkow@diskohq.org>                     *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Lesser General Public            *
 *   License version 2.1 as published by the Free Software Foundation.     *
 *                                                                         *
 *   This library 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     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this library; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
 **************************************************************************/

#include "mmsgui/fb/mmsfbconv.h"

#ifdef __HAVE_PF_AiRGB__

#include "mmstools/mmstools.h"

void mmsfb_blit_blend_coloralpha_airgb_to_airgb(MMSFBExternalSurfaceBuffer *extbuf, int src_height, int sx, int sy, int sw, int sh,
                                                unsigned int *dst, int dst_pitch, int dst_height, int dx, int dy,
                                                unsigned char alpha) {
    // check for full alpha value
    if (alpha == 0xff) {
        // max alpha is specified, so i can ignore it and use faster routine
        mmsfb_blit_blend_airgb_to_airgb(extbuf, src_height, sx, sy, sw, sh,
                                        dst, dst_pitch, dst_height, dx, dy);
        return;
    }

    // first time?
    static bool firsttime = true;
    if (firsttime) {
        printf("DISKO: Using accelerated blend coloralpha AiRGB to AiRGB.\n");
        firsttime = false;
    }

    // something to do?
    if (!alpha)
        // source should blitted full transparent, so leave destination as is
        return;

    // get the first source ptr/pitch
    unsigned int *src = (unsigned int *)extbuf->ptr;
    int src_pitch = extbuf->pitch;

    // prepare...
    int src_pitch_pix = src_pitch >> 2;
    int dst_pitch_pix = dst_pitch >> 2;
    src+= sx + sy * src_pitch_pix;
    dst+= dx + dy * dst_pitch_pix;

    // check the surface range
    if (dst_pitch_pix - dx < sw - sx)
        sw = dst_pitch_pix - dx - sx;
    if (dst_height - dy < sh - sy)
        sh = dst_height - dy - sy;
    if ((sw <= 0)||(sh <= 0))
        return;

    unsigned int OLDDST = (*dst) + 1;
    unsigned int OLDSRC  = (*src) + 1;
    unsigned int *src_end = src + src_pitch_pix * sh;
    int src_pitch_diff = src_pitch_pix - sw;
    int dst_pitch_diff = dst_pitch_pix - sw;
    register unsigned int d;

    register unsigned int ALPHA = alpha;
    ALPHA++;

    // for all lines
    while (src < src_end) {
        // for all pixels in the line
        unsigned int *line_end = src + sw;
        while (src < line_end) {
            // load pixel from memory and check if the previous pixel is the same
            register unsigned int SRC = *src;

            // is the source alpha channel 0x00 or 0xff?
            register unsigned int A = SRC >> 24;
            if (A < 0xff) {
                // source alpha is >= 0x00 and < 0xff
                register unsigned int DST = *dst;

                if ((DST==OLDDST)&&(SRC==OLDSRC)) {
                    // same pixel, use the previous value
                    *dst = d;
                    dst++;
                    src++;
                    continue;
                }
                OLDDST = DST;
                OLDSRC = SRC;

                // load source pixel and multiply it with given ALPHA
                A = 0x100 - ((ALPHA * (0x100 - A)) >> 8);
                unsigned int sr = (ALPHA * (SRC & 0xff0000)) >> 24;
                unsigned int sg = (ALPHA * (SRC & 0xff00)) >> 16;
                unsigned int sb = (ALPHA * (SRC & 0xff)) >> 8;

                unsigned int a = DST >> 24;
                unsigned int r = (DST << 8) >> 24;
                unsigned int g = (DST << 16) >> 24;
                unsigned int b = DST & 0xff;

                // invert src alpha
                a = (A * (0x100 - a)) >> 8;
                r = (A * r) >> 8;
                g = (A * g) >> 8;
                b = (A * b) >> 8;

                // add src to dst
                a += 0x100 - A;
                r += sr;
                g += sg;
                b += sb;
                d =   ((r >> 8) ? 0xff0000   : (r << 16))
                    | ((g >> 8) ? 0xff00     : (g << 8))
                    | ((b >> 8) ? 0xff       :  b);
                if (!(a >> 8)) d |= (0x100 - a) << 24;
                *dst = d;
            }

            dst++;
            src++;
        }

        // go to the next line
        src+= src_pitch_diff;
        dst+= dst_pitch_diff;
    }
}

#endif

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