SDL_blit_slow.c (6330B)
1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2020 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_internal.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 */ 30 void 31 SDL_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 Uint32 rgbmask = ~src_fmt->Amask; 50 Uint32 ckey = info->colorkey & rgbmask; 51 52 srcy = 0; 53 posy = 0; 54 incy = (info->src_h << 16) / info->dst_h; 55 incx = (info->src_w << 16) / info->dst_w; 56 57 while (info->dst_h--) { 58 Uint8 *src = 0; 59 Uint8 *dst = info->dst; 60 int n = info->dst_w; 61 srcx = -1; 62 posx = 0x10000L; 63 while (posy >= 0x10000L) { 64 ++srcy; 65 posy -= 0x10000L; 66 } 67 while (n--) { 68 if (posx >= 0x10000L) { 69 while (posx >= 0x10000L) { 70 ++srcx; 71 posx -= 0x10000L; 72 } 73 src = 74 (info->src + (srcy * info->src_pitch) + (srcx * srcbpp)); 75 } 76 if (src_fmt->Amask) { 77 DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG, 78 srcB, srcA); 79 } else { 80 DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG, 81 srcB); 82 srcA = 0xFF; 83 } 84 if (flags & SDL_COPY_COLORKEY) { 85 /* srcpixel isn't set for 24 bpp */ 86 if (srcbpp == 3) { 87 srcpixel = (srcR << src_fmt->Rshift) | 88 (srcG << src_fmt->Gshift) | (srcB << src_fmt->Bshift); 89 } 90 if ((srcpixel & rgbmask) == ckey) { 91 posx += incx; 92 dst += dstbpp; 93 continue; 94 } 95 } 96 if (dst_fmt->Amask) { 97 DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, 98 dstB, dstA); 99 } else { 100 DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG, 101 dstB); 102 dstA = 0xFF; 103 } 104 105 if (flags & SDL_COPY_MODULATE_COLOR) { 106 srcR = (srcR * modulateR) / 255; 107 srcG = (srcG * modulateG) / 255; 108 srcB = (srcB * modulateB) / 255; 109 } 110 if (flags & SDL_COPY_MODULATE_ALPHA) { 111 srcA = (srcA * modulateA) / 255; 112 } 113 if (flags & (SDL_COPY_BLEND | SDL_COPY_ADD)) { 114 /* This goes away if we ever use premultiplied alpha */ 115 if (srcA < 255) { 116 srcR = (srcR * srcA) / 255; 117 srcG = (srcG * srcA) / 255; 118 srcB = (srcB * srcA) / 255; 119 } 120 } 121 switch (flags & (SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD | SDL_COPY_MUL)) { 122 case 0: 123 dstR = srcR; 124 dstG = srcG; 125 dstB = srcB; 126 dstA = srcA; 127 break; 128 case SDL_COPY_BLEND: 129 dstR = srcR + ((255 - srcA) * dstR) / 255; 130 dstG = srcG + ((255 - srcA) * dstG) / 255; 131 dstB = srcB + ((255 - srcA) * dstB) / 255; 132 dstA = srcA + ((255 - srcA) * dstA) / 255; 133 break; 134 case SDL_COPY_ADD: 135 dstR = srcR + dstR; 136 if (dstR > 255) 137 dstR = 255; 138 dstG = srcG + dstG; 139 if (dstG > 255) 140 dstG = 255; 141 dstB = srcB + dstB; 142 if (dstB > 255) 143 dstB = 255; 144 break; 145 case SDL_COPY_MOD: 146 dstR = (srcR * dstR) / 255; 147 dstG = (srcG * dstG) / 255; 148 dstB = (srcB * dstB) / 255; 149 break; 150 case SDL_COPY_MUL: 151 dstR = ((srcR * dstR) + (dstR * (255 - srcA))) / 255; 152 if (dstR > 255) 153 dstR = 255; 154 dstG = ((srcG * dstG) + (dstG * (255 - srcA))) / 255; 155 if (dstG > 255) 156 dstG = 255; 157 dstB = ((srcB * dstB) + (dstB * (255 - srcA))) / 255; 158 if (dstB > 255) 159 dstB = 255; 160 dstA = ((srcA * dstA) + (dstA * (255 - srcA))) / 255; 161 if (dstA > 255) 162 dstA = 255; 163 break; 164 } 165 if (dst_fmt->Amask) { 166 ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA); 167 } else { 168 ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB); 169 } 170 posx += incx; 171 dst += dstbpp; 172 } 173 posy += incy; 174 info->dst += info->dst_pitch; 175 } 176 } 177 178 /* vi: set ts=4 sw=4 expandtab: */