Mercurial > sdl-ios-xcode
annotate src/video/SDL_gamma.c @ 1643:51038e80ae59
More general fix for bug #189
The clipping is done at a higher level, and the low level functions are
passed clipped rectangles. Drivers which don't support source clipping
have not been changed, so the image will be squished instead of clipped,
but at least they will no longer crash when the destination rect was out
of bounds.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 17 Apr 2006 06:47:23 +0000 |
| parents | 97d0966f4bf7 |
| children | 782fd950bd46 65800e7f7146 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
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3 Copyright (C) 1997-2006 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
|
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6 modify it under the terms of the GNU Lesser General Public |
| 0 | 7 License as published by the Free Software Foundation; either |
|
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8 version 2.1 of the License, or (at your option) any later version. |
| 0 | 9 |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
|
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13 Lesser General Public License for more details. |
| 0 | 14 |
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15 You should have received a copy of the GNU Lesser General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 0 | 18 |
| 19 Sam Lantinga | |
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20 slouken@libsdl.org |
| 0 | 21 */ |
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22 #include "SDL_config.h" |
| 0 | 23 |
| 24 /* Gamma correction support */ | |
| 25 | |
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26 #ifdef HAVE_MATH_H |
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27 #include <math.h> /* Used for calculating gamma ramps */ |
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28 #else |
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29 /* Math routines from uClibc: http://www.uclibc.org */ |
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30 #include "math_private.h" |
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31 #include "e_sqrt.h" |
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32 #include "e_pow.h" |
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33 #include "e_log.h" |
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34 #define pow(x, y) __ieee754_pow(x, y) |
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35 #define log(x) __ieee754_log(x) |
| 0 | 36 #endif |
| 37 | |
| 38 #include "SDL_sysvideo.h" | |
| 39 | |
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40 |
| 0 | 41 static void CalculateGammaRamp(float gamma, Uint16 *ramp) |
| 42 { | |
| 43 int i; | |
| 44 | |
| 45 /* 0.0 gamma is all black */ | |
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46 if ( gamma <= 0.0f ) { |
| 0 | 47 for ( i=0; i<256; ++i ) { |
| 48 ramp[i] = 0; | |
| 49 } | |
| 50 return; | |
| 51 } else | |
| 52 /* 1.0 gamma is identity */ | |
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53 if ( gamma >= 1.0f ) { |
| 0 | 54 for ( i=0; i<256; ++i ) { |
| 55 ramp[i] = (i << 8) | i; | |
| 56 } | |
| 57 return; | |
| 58 } else | |
| 59 /* Calculate a real gamma ramp */ | |
| 60 { int value; | |
| 61 gamma = 1.0f / gamma; | |
| 62 for ( i=0; i<256; ++i ) { | |
| 63 value = (int)(pow((double)i/256.0, gamma)*65535.0+0.5); | |
| 64 if ( value > 65535 ) { | |
| 65 value = 65535; | |
| 66 } | |
| 67 ramp[i] = (Uint16)value; | |
| 68 } | |
| 69 } | |
| 70 } | |
| 71 static void CalculateGammaFromRamp(float *gamma, Uint16 *ramp) | |
| 72 { | |
| 73 /* The following is adapted from a post by Garrett Bass on OpenGL | |
| 74 Gamedev list, March 4, 2000. | |
| 75 */ | |
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76 float sum = 0.0f; |
| 0 | 77 int i, count = 0; |
| 78 | |
| 79 *gamma = 1.0; | |
| 80 for ( i = 1; i < 256; ++i ) { | |
| 81 if ( (ramp[i] != 0) && (ramp[i] != 65535) ) { | |
| 82 double B = (double)i / 256.0; | |
| 83 double A = ramp[i] / 65535.0; | |
| 84 sum += (float) ( log(A) / log(B) ); | |
| 85 count++; | |
| 86 } | |
| 87 } | |
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88 if ( count && sum > 0.0f ) { |
| 0 | 89 *gamma = 1.0f / (sum / count); |
| 90 } | |
| 91 } | |
| 92 | |
| 93 int SDL_SetGamma(float red, float green, float blue) | |
| 94 { | |
| 95 int succeeded; | |
| 96 SDL_VideoDevice *video = current_video; | |
| 97 SDL_VideoDevice *this = current_video; | |
| 98 | |
| 99 succeeded = -1; | |
| 100 /* Prefer using SetGammaRamp(), as it's more flexible */ | |
| 101 { | |
| 102 Uint16 ramp[3][256]; | |
| 103 | |
| 104 CalculateGammaRamp(red, ramp[0]); | |
| 105 CalculateGammaRamp(green, ramp[1]); | |
| 106 CalculateGammaRamp(blue, ramp[2]); | |
| 107 succeeded = SDL_SetGammaRamp(ramp[0], ramp[1], ramp[2]); | |
| 108 } | |
| 109 if ( (succeeded < 0) && video->SetGamma ) { | |
| 110 SDL_ClearError(); | |
| 111 succeeded = video->SetGamma(this, red, green, blue); | |
| 112 } | |
| 113 return succeeded; | |
| 114 } | |
| 115 | |
| 116 /* Calculating the gamma by integrating the gamma ramps isn't exact, | |
| 117 so this function isn't officially supported. | |
| 118 */ | |
| 119 int SDL_GetGamma(float *red, float *green, float *blue) | |
| 120 { | |
| 121 int succeeded; | |
| 122 SDL_VideoDevice *video = current_video; | |
| 123 SDL_VideoDevice *this = current_video; | |
| 124 | |
| 125 succeeded = -1; | |
| 126 /* Prefer using GetGammaRamp(), as it's more flexible */ | |
| 127 { | |
| 128 Uint16 ramp[3][256]; | |
| 129 | |
| 130 succeeded = SDL_GetGammaRamp(ramp[0], ramp[1], ramp[2]); | |
| 131 if ( succeeded >= 0 ) { | |
| 132 CalculateGammaFromRamp(red, ramp[0]); | |
| 133 CalculateGammaFromRamp(green, ramp[1]); | |
| 134 CalculateGammaFromRamp(blue, ramp[2]); | |
| 135 } | |
| 136 } | |
| 137 if ( (succeeded < 0) && video->GetGamma ) { | |
| 138 SDL_ClearError(); | |
| 139 succeeded = video->GetGamma(this, red, green, blue); | |
| 140 } | |
| 141 return succeeded; | |
| 142 } | |
| 143 | |
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144 int SDL_SetGammaRamp(const Uint16 *red, const Uint16 *green, const Uint16 *blue) |
| 0 | 145 { |
| 146 int succeeded; | |
| 147 SDL_VideoDevice *video = current_video; | |
| 148 SDL_VideoDevice *this = current_video; | |
| 149 SDL_Surface *screen = SDL_PublicSurface; | |
| 150 | |
| 151 /* Verify the screen parameter */ | |
| 152 if ( !screen ) { | |
| 153 SDL_SetError("No video mode has been set"); | |
| 154 return -1; | |
| 155 } | |
| 156 | |
| 157 /* Lazily allocate the gamma tables */ | |
| 158 if ( ! video->gamma ) { | |
| 159 SDL_GetGammaRamp(0, 0, 0); | |
| 160 } | |
| 161 | |
| 162 /* Fill the gamma table with the new values */ | |
| 163 if ( red ) { | |
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164 SDL_memcpy(&video->gamma[0*256], red, 256*sizeof(*video->gamma)); |
| 0 | 165 } |
| 166 if ( green ) { | |
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167 SDL_memcpy(&video->gamma[1*256], green, 256*sizeof(*video->gamma)); |
| 0 | 168 } |
| 169 if ( blue ) { | |
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170 SDL_memcpy(&video->gamma[2*256], blue, 256*sizeof(*video->gamma)); |
| 0 | 171 } |
| 172 | |
| 173 /* Gamma correction always possible on split palettes */ | |
| 174 if ( (screen->flags & SDL_HWPALETTE) == SDL_HWPALETTE ) { | |
| 175 SDL_Palette *pal = screen->format->palette; | |
| 176 | |
| 177 /* If physical palette has been set independently, use it */ | |
| 178 if(video->physpal) | |
| 179 pal = video->physpal; | |
| 180 | |
| 181 SDL_SetPalette(screen, SDL_PHYSPAL, | |
| 182 pal->colors, 0, pal->ncolors); | |
| 183 return 0; | |
| 184 } | |
| 185 | |
| 186 /* Try to set the gamma ramp in the driver */ | |
| 187 succeeded = -1; | |
| 188 if ( video->SetGammaRamp ) { | |
| 189 succeeded = video->SetGammaRamp(this, video->gamma); | |
| 190 } else { | |
| 191 SDL_SetError("Gamma ramp manipulation not supported"); | |
| 192 } | |
| 193 return succeeded; | |
| 194 } | |
| 195 | |
| 196 int SDL_GetGammaRamp(Uint16 *red, Uint16 *green, Uint16 *blue) | |
| 197 { | |
| 198 SDL_VideoDevice *video = current_video; | |
| 199 SDL_VideoDevice *this = current_video; | |
| 200 | |
| 201 /* Lazily allocate the gamma table */ | |
| 202 if ( ! video->gamma ) { | |
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203 video->gamma = SDL_malloc(3*256*sizeof(*video->gamma)); |
| 0 | 204 if ( ! video->gamma ) { |
| 205 SDL_OutOfMemory(); | |
| 206 return -1; | |
| 207 } | |
| 208 if ( video->GetGammaRamp ) { | |
| 209 /* Get the real hardware gamma */ | |
| 210 video->GetGammaRamp(this, video->gamma); | |
| 211 } else { | |
| 212 /* Assume an identity gamma */ | |
| 213 int i; | |
| 214 for ( i=0; i<256; ++i ) { | |
| 215 video->gamma[0*256+i] = (i << 8) | i; | |
| 216 video->gamma[1*256+i] = (i << 8) | i; | |
| 217 video->gamma[2*256+i] = (i << 8) | i; | |
| 218 } | |
| 219 } | |
| 220 } | |
| 221 | |
| 222 /* Just copy from our internal table */ | |
| 223 if ( red ) { | |
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224 SDL_memcpy(red, &video->gamma[0*256], 256*sizeof(*red)); |
| 0 | 225 } |
| 226 if ( green ) { | |
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227 SDL_memcpy(green, &video->gamma[1*256], 256*sizeof(*green)); |
| 0 | 228 } |
| 229 if ( blue ) { | |
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230 SDL_memcpy(blue, &video->gamma[2*256], 256*sizeof(*blue)); |
| 0 | 231 } |
| 232 return 0; | |
| 233 } |