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/project/jni/sdl-1.3/src/video/SDL_blit_slow.c

https://github.com/aichunyu/FFPlayer
C | 161 lines | 129 code | 6 blank | 26 comment | 24 complexity | d0789348ed47cfa70d00edf6f7174a11 MD5 | raw file
  1/*
  2  Simple DirectMedia Layer
  3  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
  4
  5  This software is provided 'as-is', without any express or implied
  6  warranty.  In no event will the authors be held liable for any damages
  7  arising from the use of this software.
  8
  9  Permission is granted to anyone to use this software for any purpose,
 10  including commercial applications, and to alter it and redistribute it
 11  freely, subject to the following restrictions:
 12
 13  1. The origin of this software must not be misrepresented; you must not
 14     claim that you wrote the original software. If you use this software
 15     in a product, an acknowledgment in the product documentation would be
 16     appreciated but is not required.
 17  2. Altered source versions must be plainly marked as such, and must not be
 18     misrepresented as being the original software.
 19  3. This notice may not be removed or altered from any source distribution.
 20*/
 21#include "SDL_config.h"
 22
 23#include "SDL_video.h"
 24#include "SDL_blit.h"
 25#include "SDL_blit_slow.h"
 26
 27/* The ONE TRUE BLITTER
 28 * This puppy has to handle all the unoptimized cases - yes, it's slow.
 29 */
 30void
 31SDL_Blit_Slow(SDL_BlitInfo * info)
 32{
 33    const int flags = info->flags;
 34    const Uint32 modulateR = info->r;
 35    const Uint32 modulateG = info->g;
 36    const Uint32 modulateB = info->b;
 37    const Uint32 modulateA = info->a;
 38    Uint32 srcpixel;
 39    Uint32 srcR, srcG, srcB, srcA;
 40    Uint32 dstpixel;
 41    Uint32 dstR, dstG, dstB, dstA;
 42    int srcy, srcx;
 43    int posy, posx;
 44    int incy, incx;
 45    SDL_PixelFormat *src_fmt = info->src_fmt;
 46    SDL_PixelFormat *dst_fmt = info->dst_fmt;
 47    int srcbpp = src_fmt->BytesPerPixel;
 48    int dstbpp = dst_fmt->BytesPerPixel;
 49
 50    srcy = 0;
 51    posy = 0;
 52    incy = (info->src_h << 16) / info->dst_h;
 53    incx = (info->src_w << 16) / info->dst_w;
 54
 55    while (info->dst_h--) {
 56        Uint8 *src = 0;
 57        Uint8 *dst = (Uint8 *) info->dst;
 58        int n = info->dst_w;
 59        srcx = -1;
 60        posx = 0x10000L;
 61        while (posy >= 0x10000L) {
 62            ++srcy;
 63            posy -= 0x10000L;
 64        }
 65        while (n--) {
 66            if (posx >= 0x10000L) {
 67                while (posx >= 0x10000L) {
 68                    ++srcx;
 69                    posx -= 0x10000L;
 70                }
 71                src =
 72                    (info->src + (srcy * info->src_pitch) + (srcx * srcbpp));
 73            }
 74            if (src_fmt->Amask) {
 75                DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
 76                              srcB, srcA);
 77            } else {
 78                DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
 79                             srcB);
 80                srcA = 0xFF;
 81            }
 82            if (flags & SDL_COPY_COLORKEY) {
 83                /* srcpixel isn't set for 24 bpp */
 84                if (srcbpp == 3) {
 85                    srcpixel = (srcR << src_fmt->Rshift) |
 86                        (srcG << src_fmt->Gshift) | (srcB << src_fmt->Bshift);
 87                }
 88                if (srcpixel == info->colorkey) {
 89                    posx += incx;
 90                    dst += dstbpp;
 91                    continue;
 92                }
 93            }
 94            if (dst_fmt->Amask) {
 95                DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
 96                              dstB, dstA);
 97            } else {
 98                DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
 99                             dstB);
100                dstA = 0xFF;
101            }
102
103            if (flags & SDL_COPY_MODULATE_COLOR) {
104                srcR = (srcR * modulateR) / 255;
105                srcG = (srcG * modulateG) / 255;
106                srcB = (srcB * modulateB) / 255;
107            }
108            if (flags & SDL_COPY_MODULATE_ALPHA) {
109                srcA = (srcA * modulateA) / 255;
110            }
111            if (flags & (SDL_COPY_BLEND | SDL_COPY_ADD)) {
112                /* This goes away if we ever use premultiplied alpha */
113                if (srcA < 255) {
114                    srcR = (srcR * srcA) / 255;
115                    srcG = (srcG * srcA) / 255;
116                    srcB = (srcB * srcA) / 255;
117                }
118            }
119            switch (flags & (SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD)) {
120            case 0:
121                dstR = srcR;
122                dstG = srcG;
123                dstB = srcB;
124                dstA = srcA;
125                break;
126            case SDL_COPY_BLEND:
127                dstR = srcR + ((255 - srcA) * dstR) / 255;
128                dstG = srcG + ((255 - srcA) * dstG) / 255;
129                dstB = srcB + ((255 - srcA) * dstB) / 255;
130                break;
131            case SDL_COPY_ADD:
132                dstR = srcR + dstR;
133                if (dstR > 255)
134                    dstR = 255;
135                dstG = srcG + dstG;
136                if (dstG > 255)
137                    dstG = 255;
138                dstB = srcB + dstB;
139                if (dstB > 255)
140                    dstB = 255;
141                break;
142            case SDL_COPY_MOD:
143                dstR = (srcR * dstR) / 255;
144                dstG = (srcG * dstG) / 255;
145                dstB = (srcB * dstB) / 255;
146                break;
147            }
148            if (dst_fmt->Amask) {
149                ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA);
150            } else {
151                ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB);
152            }
153            posx += incx;
154            dst += dstbpp;
155        }
156        posy += incy;
157        info->dst += info->dst_pitch;
158    }
159}
160
161/* vi: set ts=4 sw=4 expandtab: */