demos: Add checkerboard demo

This is a simple demo that displays a checkboard with a projective
transformation.

2 files changed, 75 insertions, 1 deletions

diff --git a/demos/Makefile.am b/demos/Makefile.am
index 070c2d7..6049090 100644
--- a/demos/Makefile.am
+++ b/demos/Makefile.am
@@ -18,7 +18,9 @@ DEMOS =				\
 	screen-test		\
 	convolution-test	\
 	trap-test		\
-	tri-test
+	tri-test		\
+	quad2quad		\
+	checkerboard
 
 gradient_test_SOURCES = gradient-test.c $(GTK_UTILS)
 alpha_test_SOURCES = alpha-test.c $(GTK_UTILS)
@@ -30,6 +32,7 @@ screen_test_SOURCES = screen-test.c $(GTK_UTILS)
 convolution_test_SOURCES = convolution-test.c $(GTK_UTILS)
 radial_test_SOURCES = radial-test.c ../test/utils.c ../test/utils.h $(GTK_UTILS)
 tri_test_SOURCES = tri-test.c ../test/utils.c ../test/utils.h $(GTK_UTILS)
+checkerboard_SOURCES = checkerboard.c $(GTK_UTILS)
 
 noinst_PROGRAMS = $(DEMOS)
 
diff --git a/demos/checkerboard.c b/demos/checkerboard.c
new file mode 100644
index 0000000..449fedb
--- /dev/null
+++ b/demos/checkerboard.c
@@ -0,0 +1,71 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "pixman.h"
+#include "gtk-utils.h"
+
+int
+main (int argc, char **argv)
+{
+#define WIDTH 400
+#define HEIGHT 400
+#define TILE_SIZE 25
+
+    pixman_image_t *checkerboard;
+    pixman_image_t *destination;
+#define D2F(d) (pixman_double_to_fixed(d))
+    pixman_transform_t trans = { {
+	    { D2F (-1.96830), D2F (-1.82250), D2F (512.12250)},
+	    { D2F (0.00000), D2F (-7.29000), D2F (1458.00000)},
+	    { D2F (0.00000), D2F (-0.00911), D2F (0.59231)},
+	}};
+    int i, j;
+
+    checkerboard = pixman_image_create_bits (PIXMAN_a8r8g8b8,
+					     WIDTH, HEIGHT,
+					     NULL, 0);
+
+    destination = pixman_image_create_bits (PIXMAN_a8r8g8b8,
+					    WIDTH, HEIGHT,
+					    NULL, 0);
+
+    for (i = 0; i < HEIGHT / TILE_SIZE; ++i)
+    {
+	for (j = 0; j < WIDTH / TILE_SIZE; ++j)
+	{
+	    double u = (double)(j + 1) / (WIDTH / TILE_SIZE);
+	    double v = (double)(i + 1) / (HEIGHT / TILE_SIZE);
+	    pixman_color_t black = { 0, 0, 0, 0xffff };
+	    pixman_color_t white = {
+		v * 0xffff,
+		u * 0xffff,
+		(1 - (double)u) * 0xffff,
+		0xffff };
+	    pixman_color_t *c;
+	    pixman_image_t *fill;
+
+	    if ((j & 1) != (i & 1))
+		c = &black;
+	    else
+		c = &white;
+
+	    fill = pixman_image_create_solid_fill (c);
+
+	    pixman_image_composite (PIXMAN_OP_SRC, fill, NULL, checkerboard,
+				    0, 0, 0, 0, j * TILE_SIZE, i * TILE_SIZE,
+				    TILE_SIZE, TILE_SIZE);
+	}
+    }
+
+    pixman_image_set_transform (checkerboard, &trans);
+    pixman_image_set_filter (checkerboard, PIXMAN_FILTER_BEST, NULL, 0);
+    pixman_image_set_repeat (checkerboard, PIXMAN_REPEAT_NONE);
+
+    pixman_image_composite (PIXMAN_OP_SRC,
+			    checkerboard, NULL, destination,
+			    0, 0, 0, 0, 0, 0,
+			    WIDTH, HEIGHT);
+
+    show_image (destination);
+
+    return 0;
+}