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Diffstat (limited to 'libdimension/canvas.c')
| -rw-r--r-- | libdimension/canvas.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/libdimension/canvas.c b/libdimension/canvas.c new file mode 100644 index 0000000..c730b53 --- /dev/null +++ b/libdimension/canvas.c @@ -0,0 +1,203 @@ +/************************************************************************* + * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> * + * * + * This file is part of Dimension. * + * * + * Dimension is free software; you can redistribute it and/or modify it * + * under the terms of the GNU Lesser General Public License as published * + * by the Free Software Foundation; either version 3 of the License, or * + * (at your option) any later version. * + * * + * Dimension 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 program. If not, see * + * <http://www.gnu.org/licenses/>. * + *************************************************************************/ + +#include "dimension.h" +#include <math.h> +#include <stdlib.h> + +/* Conversions between CIE 1931 XYZ and sRGB color. */ + +dmnsn_pixel +dmnsn_pixel_from_color(dmnsn_color color) +{ + double Rlinear, Glinear, Blinear; /* Linear RGB values - no gamma */ + double R, G, B; /* sRGB values */ + dmnsn_pixel pixel; + + /* + * First, the linear conversion. Expressed as matrix multiplication, it looks + * like this: + * + * [Rlinear] [ 3.2410 -1.5374 -0.4986] [X] + * [Glinear] = [-0.9692 1.8760 0.0416]*[Y] + * [Blinear] [ 0.0556 -0.2040 1.0570] [Z] + */ + Rlinear = 3.2410*color.X - 1.5374*color.Y - 0.4986*color.Z; + Glinear = -0.9692*color.X + 1.8760*color.Y + 0.0416*color.Z; + Blinear = 0.0556*color.X - 0.2040*color.Y + 1.0570*color.Z; + + /* + * If C represents R, G, and B, then the sRGB values are now found as follows: + * + * { 12.92*Clinear, Clinear <= 0.0031308 + * Csrgb = { 1/2.4 + * { (1.055)*Clinear - 0.055, Clinear > 0.0031308 + */ + + if (Rlinear <= 0.0031308) { + R = 12.92*Rlinear; + } else { + R = 1.055*pow(Rlinear, 1.0/2.4) - 0.055; + } + + if (Glinear <= 0.0031308) { + G = 12.92*Glinear; + } else { + G = 1.055*pow(Glinear, 1.0/2.4) - 0.055; + } + + if (Blinear <= 0.0031308) { + B = 12.92*Blinear; + } else { + B = 1.055*pow(Blinear, 1.0/2.4) - 0.055; + } + + /* Now we go from unlimited to limited light, saturating at UINT16_MAX */ + + if (R < 0) { + pixel.r = 0; + } else if (R > 1) { + pixel.r = UINT16_MAX; + } else { + pixel.r = UINT16_MAX*R; + } + + if (G < 0) { + pixel.g = 0; + } else if (G > 1) { + pixel.g = UINT16_MAX; + } else { + pixel.g = UINT16_MAX*G; + } + + if (B < 0) { + pixel.b = 0; + } else if (B > 1) { + pixel.b = UINT16_MAX; + } else { + pixel.b = UINT16_MAX*B; + } + + if (color.alpha < 0) { + pixel.a = 0; + } else if (color.alpha > 1) { + pixel.a = UINT16_MAX; + } else { + pixel.a = UINT16_MAX*color.alpha; + } + + if (color.trans < 0) { + pixel.t = 0; + } else if (color.trans > 1) { + pixel.t = UINT16_MAX; + } else { + pixel.t = UINT16_MAX*color.trans; + } + + return pixel; +} + +dmnsn_color +dmnsn_color_from_pixel(dmnsn_pixel pixel) +{ + double R, G, B; /* sRGB values */ + double Rlinear, Glinear, Blinear; /* Linear RGB values - no gamma */ + dmnsn_color color; + + /* Conversion back to unlimited light */ + R = ((double)pixel.r)/UINT16_MAX; + G = ((double)pixel.g)/UINT16_MAX; + B = ((double)pixel.b)/UINT16_MAX; + + /* + * If C represents R, G, and B, then the Clinear values are now found as + * follows: + * + * { Csrgb/12.92, Csrgb <= 0.04045 + * Clinear = { 1/2.4 + * { ((Csrgb + 0.055)/1.055) , Csrgb > 0.04045 + */ + + if (R <= 0.04045) { + Rlinear = R/19.92; + } else { + Rlinear = pow((R + 0.055)/1.055, 2.4); + } + + if (G <= 0.04045) { + Glinear = G/19.92; + } else { + Glinear = pow((G + 0.055)/1.055, 2.4); + } + + if (B <= 0.04045) { + Blinear = B/19.92; + } else { + Blinear = pow((B + 0.055)/1.055, 2.4); + } + + /* + * Now, the linear conversion. Expressed as matrix multiplication, it looks + * like this: + * + * [X] [0.4124 0.3576 0.1805] [Rlinear] + * [Y] = [0.2126 0.7152 0.0722]*[Glinear] + * [X] [0.0193 0.1192 0.9505] [Blinear] + */ + + color.X = 0.4124*Rlinear + 0.3576*Glinear + 0.1805*Blinear; + color.Y = 0.2126*Rlinear + 0.7152*Glinear + 0.0722*Blinear; + color.Z = 0.0193*Rlinear + 0.1192*Glinear + 0.9505*Blinear; + + color.alpha = ((double)pixel.a)/UINT16_MAX; + color.trans = ((double)pixel.t)/UINT16_MAX; + + return color; +} + +dmnsn_canvas * +dmnsn_new_canvas(unsigned int x, unsigned int y) +{ + dmnsn_canvas *canvas = malloc(sizeof(dmnsn_canvas)); + + if (canvas) { + canvas->x = x; + canvas->y = y; + canvas->pixels = malloc(sizeof(dmnsn_pixel)*x*y); + + if (canvas->pixels) { + return canvas; + } else { + free(canvas); + return NULL; + } + } else { + return NULL; + } +} + +void +dmnsn_delete_canvas(dmnsn_canvas *canvas) +{ + if (canvas) { + free(canvas->pixels); + free(canvas); + } +} |