SDL_blit_slow.c (5592B)
1/* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2014 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 */ 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: */