IABSD.fr/xenocara/lib/pixman/demos/srgb-test.c

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• Author : matthieu
  Date : 2012-11-23 20:44:07
  Hash : 87d6a5b7
  Message : Update to pixman 0.28.0. Tested by ajacoutot@, mpi@ and naddy@ in a full ports build. Tweaks from mpi@ for macppc.

• lib/pixman/demos/srgb-test.c

• #include <math.h>
  
  #include "pixman.h"
  #include "gtk-utils.h"
  
  static uint32_t
  linear_argb_to_premult_argb (float a,
  			     float r,
  			     float g,
  			     float b)
  {
      r *= a;
      g *= a;
      b *= a;
      return (uint32_t) (a * 255.0f + 0.5f) << 24
  	 | (uint32_t) (r * 255.0f + 0.5f) << 16
  	 | (uint32_t) (g * 255.0f + 0.5f) <<  8
  	 | (uint32_t) (b * 255.0f + 0.5f) <<  0;
  }
  
  static float
  lin2srgb (float linear)
  {
      if (linear < 0.0031308f)
  	return linear * 12.92f;
      else
  	return 1.055f * powf (linear, 1.0f/2.4f) - 0.055f;
  }
  
  static uint32_t
  linear_argb_to_premult_srgb_argb (float a,
  				  float r,
  				  float g,
  				  float b)
  {
      r = lin2srgb (r * a);
      g = lin2srgb (g * a);
      b = lin2srgb (b * a);
      return (uint32_t) (a * 255.0f + 0.5f) << 24
  	 | (uint32_t) (r * 255.0f + 0.5f) << 16
  	 | (uint32_t) (g * 255.0f + 0.5f) <<  8
  	 | (uint32_t) (b * 255.0f + 0.5f) <<  0;
  }
  
  int
  main (int argc, char **argv)
  {
  #define WIDTH 400
  #define HEIGHT 200
      int y, x, p;
      float alpha;
   
      uint32_t *dest = malloc (WIDTH * HEIGHT * 4);
      uint32_t *src1 = malloc (WIDTH * HEIGHT * 4);
      pixman_image_t *dest_img, *src1_img;
     
      dest_img = pixman_image_create_bits (PIXMAN_a8r8g8b8_sRGB,
  					 WIDTH, HEIGHT,
  					 dest,
  					 WIDTH * 4);
      src1_img = pixman_image_create_bits (PIXMAN_a8r8g8b8,
  					 WIDTH, HEIGHT,
  					 src1,
  					 WIDTH * 4);
  
      for (y = 0; y < HEIGHT; y ++)
      {
  	p = WIDTH * y;
  	for (x = 0; x < WIDTH; x ++)
  	{
  	     alpha = (float) x / WIDTH;
  	     src1[p + x] = linear_argb_to_premult_argb (alpha, 1, 0, 1);
  	     dest[p + x] = linear_argb_to_premult_srgb_argb (1-alpha, 0, 1, 0);
  	}
      }
      
      pixman_image_composite (PIXMAN_OP_ADD, src1_img, NULL, dest_img,
  			    0, 0, 0, 0, 0, 0, WIDTH, HEIGHT);
      pixman_image_unref (src1_img);
      free (src1);
  
      show_image (dest_img);
      pixman_image_unref (dest_img);
      free (dest);
      
      return 0;
  }