2 files changed, 99 insertions, 1 deletions
diff --git a/pixman/demos/Makefile.am b/pixman/demos/Makefile.am
index 9aac1f5e9..d8fb0dab2 100644
--- a/pixman/demos/Makefile.am
+++ b/pixman/demos/Makefile.am
@@ -20,7 +20,8 @@ DEMOS =				\
 	trap-test		\
 	tri-test		\
 	quad2quad		\
-	checkerboard
+	checkerboard		\
+	srgb-test
 
 EXTRA_DIST = parrot.c parrot.jpg
 
@@ -35,6 +36,7 @@ convolution_test_SOURCES = convolution-test.c $(GTK_UTILS)
 radial_test_SOURCES = radial-test.c $(GTK_UTILS)
 tri_test_SOURCES = tri-test.c $(GTK_UTILS)
 checkerboard_SOURCES = checkerboard.c $(GTK_UTILS)
+srgb_test_SOURCES = srgb-test.c $(GTK_UTILS)
 
 noinst_PROGRAMS = $(DEMOS)
 
diff --git a/pixman/demos/srgb-test.c b/pixman/demos/srgb-test.c
new file mode 100644
index 000000000..bc073491e
--- /dev/null
+++ b/pixman/demos/srgb-test.c
@@ -0,0 +1,96 @@
+#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);
+
+    pixman_image_unref (dest_img);
+
+    /* Now that the picture has been correctly constructed,
+     * we hand it over to our support library as argb which it
+     * knows how to handle (it doesn't understand _sRGB format). */
+    dest_img = pixman_image_create_bits (PIXMAN_a8r8g8b8,
+			 		 WIDTH, HEIGHT,
+					 dest,
+					 WIDTH * 4);
+    show_image (dest_img);
+    pixman_image_unref (dest_img);
+    free (dest);
+    
+    return 0;
+}