mmsfb_drawstring_blend_coloralpha_rgb32.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"
#include "mmstools/mmstools.h"

void mmsfb_drawstring_blend_coloralpha_rgb32(MMSFBSurfacePlanes *dst_planes, MMSFBFont *font,
                                             MMSFBRegion &clipreg, string &text, int len, int x, int y, MMSFBColor &color) {
    // check for full alpha value
    if (color.a == 0xff) {
        // max alpha is specified, so i can ignore it and use faster routine
        mmsfb_drawstring_blend_rgb32(dst_planes, font, clipreg, text, len, x, y, color);
        return;
    }

    // get the first destination ptr/pitch
    void *dst_ptr = dst_planes->ptr;
    int dst_pitch = dst_planes->pitch;

    // first time?
    static bool firsttime = true;
    if (firsttime) {
        printf("DISKO: Using blend text coloralpha RGB32.\n");
        firsttime = false;
    }

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

    // lock font and destination surface
    MMSFBSURFACE_BLIT_TEXT_INIT(2);

    // for all characters
    unsigned int OLDDST = 0;
    unsigned int OLDSRC = 0;
    register unsigned int d = 0;
    register unsigned int ALPHA = color.a;
    ALPHA++;
    MMSFBFONT_GET_UNICODE_CHAR(text, len) {
        // load the glyph
        MMSFBSURFACE_BLIT_TEXT_LOAD_GLYPH(font, character);

        // start rendering of glyph to destination
        MMSFBSURFACE_BLIT_TEXT_START_RENDER(unsigned int);

        // through the pixels
        while (src < src_end) {
            while (src < line_end) {
                // load pixel from memory
                register unsigned int SRC = *src;

                // is the source alpha channel 0x00 or 0xff?
                register unsigned int A = SRC;
                if (A) {
                    // 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;

                    A = (ALPHA * A) >> 8;
                    register unsigned int SA= 0x100 - A;
                    unsigned int r = (DST << 8) >> 24;
                    unsigned int g = (DST << 16) >> 24;
                    unsigned int b = DST & 0xff;

                    // invert src alpha
                    r = (SA * r) >> 8;
                    g = (SA * g) >> 8;
                    b = (SA * b) >> 8;

                    // add src to dst
                    r += (A * color.r) >> 8;
                    g += (A * color.g) >> 8;
                    b += (A * color.b) >> 8;
                    d =   0xff000000
                        | ((r >> 8) ? 0xff0000   : (r << 16))
                        | ((g >> 8) ? 0xff00     : (g << 8))
                        | ((b >> 8) ? 0xff       :  b);
                    *dst = d;
                }

                src++;
                dst++;
            }
            line_end+= src_pitch_pix;
            src     += src_pitch_pix_diff;
            dst     += dst_pitch_pix_diff;
        }

        // prepare for next loop
        MMSFBSURFACE_BLIT_TEXT_END_RENDER;
    }}
}

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