Added some tests of composite to highlight problems in the old

	* gdk-pixbuf/.cvsignore:
	* gdk-pixbuf/Makefile.am:
	* gdk-pixbuf/test-gdk-pixbuf.c (store_pixel), (fill_with_pixel),
	(load_pixel), (simple_composite_test_one),
	(simple_composite_test_one_type), (simple_composite_test), (main):
	Added some tests of composite to highlight problems in the old
	implementation. These tests run without any user interaction.
	Just do "make check".

	* gdk-pixbuf/pixops/pixops.c (pixops_composite_nearest),
	(composite_pixel), (composite_line): Fix composite to do a textbook
	"A over B" composite. This was clearly the intent, and it was easy
	to fix the code to do it. (Note to those that read my earlier tries
	at a patch; this version fixes typos that were present in all
	my patch attempts. I checked the final version by adding more tests.)

1 files changed, 205 insertions, 0 deletions

diff --git a/gdk-pixbuf/test-gdk-pixbuf.c b/gdk-pixbuf/test-gdk-pixbuf.c
index 5b96dddd0..b75f2e65e 100644
--- a/gdk-pixbuf/test-gdk-pixbuf.c
+++ b/gdk-pixbuf/test-gdk-pixbuf.c
@@ -1,3 +1,5 @@
+/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
+
 /* GdkPixbuf library - test program
  *
  * Copyright (C) 1999 The Free Software Foundation
@@ -27,7 +29,210 @@
 
 
 
+static void
+store_pixel (guchar *pixels,
+	     int pixel,
+	     gboolean alpha)
+{
+	if (alpha) {
+		pixels[0] = pixel >> 24;
+		pixels[1] = pixel >> 16;
+		pixels[2] = pixel >> 8;
+		pixels[3] = pixel;
+	} else {
+		pixels[0] = pixel >> 16;
+		pixels[1] = pixel >> 8;
+		pixels[2] = pixel;
+	}
+}
+
+static void
+fill_with_pixel (GdkPixbuf *pixbuf,
+		 int pixel)
+{
+	int x, y;
+	
+	for (x = 0; x < gdk_pixbuf_get_width (pixbuf); x++) {
+		for (y = 0; y < gdk_pixbuf_get_height (pixbuf); y++) {
+			store_pixel (gdk_pixbuf_get_pixels (pixbuf)
+				     + y * gdk_pixbuf_get_rowstride (pixbuf)
+				     + x * gdk_pixbuf_get_n_channels (pixbuf),
+				     pixel,
+				     gdk_pixbuf_get_has_alpha (pixbuf));
+		}
+	}
+}
+
+static int
+load_pixel (const guchar *pixels,
+	    gboolean alpha)
+{
+	if (alpha)
+		return (((((pixels[0] << 8) | pixels[1]) << 8) | pixels[2]) << 8) | pixels[3];
+	else
+		return (((pixels[0] << 8) | pixels[1]) << 8) | pixels[2];
+}
+
+static gboolean
+simple_composite_test_one (GdkInterpType type,
+			   int source_pixel,
+			   gboolean source_alpha,
+			   int destination_pixel,
+			   gboolean destination_alpha,
+			   int expected_result)
+{
+	GdkPixbuf *source_pixbuf;
+	GdkPixbuf *destination_pixbuf;
+	int result_pixel;
+
+	source_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, source_alpha, 8, 32, 32);
+	destination_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, destination_alpha, 8, 32, 32);
+	
+	fill_with_pixel (source_pixbuf, source_pixel);
+	fill_with_pixel (destination_pixbuf, destination_pixel);
+
+	gdk_pixbuf_composite (source_pixbuf, destination_pixbuf,
+			      0, 0, 32, 32, 0, 0, 1, 1, type, 0xFF);
+
+	result_pixel = load_pixel (gdk_pixbuf_get_pixels (destination_pixbuf)
+				   + 16 * gdk_pixbuf_get_rowstride (destination_pixbuf)
+				   + 16 * gdk_pixbuf_get_n_channels (destination_pixbuf),
+				   destination_alpha);
+	  
+	gdk_pixbuf_unref (source_pixbuf);
+	gdk_pixbuf_unref (destination_pixbuf);
+
+	if (result_pixel != expected_result) {
+		char *interpolation_type, *source_string, *destination_string, *result_string, *expected_string;
+
+		switch (type) {
+		case GDK_INTERP_NEAREST:  interpolation_type = "GDK_INTERP_NEAREST"; break;
+		case GDK_INTERP_TILES:    interpolation_type = "GDK_INTERP_TILES"; break;
+		case GDK_INTERP_BILINEAR: interpolation_type = "GDK_INTERP_BILINEAR"; break;
+		case GDK_INTERP_HYPER:    interpolation_type = "GDK_INTERP_HYPER"; break;
+		default:                  interpolation_type = "???";
+		}
+
+		if (source_alpha) {
+			source_string = g_strdup_printf ("0x%08X", source_pixel);
+		} else {
+			source_string = g_strdup_printf ("0x%06X", source_pixel);
+		}
+
+		if (destination_alpha) {
+			destination_string = g_strdup_printf ("0x%08X", destination_pixel);
+			result_string = g_strdup_printf ("0x%08X", result_pixel);
+			expected_string = g_strdup_printf ("0x%08X", expected_result);
+		} else {
+			destination_string = g_strdup_printf ("0x%06X", destination_pixel);
+			result_string = g_strdup_printf ("0x%06X", result_pixel);
+			expected_string = g_strdup_printf ("0x%06X", expected_result);
+		}
+
+		g_message ("simple_composite_test (%s): composite %s on top of %s, expected %s, got %s",
+			   interpolation_type,
+			   source_string, destination_string, expected_string, result_string);
+		return FALSE;
+	}
+
+	return TRUE;
+}
+
+static gboolean
+simple_composite_test_one_type (GdkInterpType type)
+{
+	gboolean success;
+
+	success = TRUE;
+
+	/* There are only a few trivial cases in here.
+	 * But these were enough to expose the problems in the old composite code.
+	 */
+
+	/* Non-alpha into non-alpha. */
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x000000, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0xFFFFFF, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0xFF0000, FALSE, 0x000000, FALSE, 0xFF0000);
+	success &= simple_composite_test_one (type, 0x00FF00, FALSE, 0x000000, FALSE, 0x00FF00);
+	success &= simple_composite_test_one (type, 0x0000FF, FALSE, 0x000000, FALSE, 0x0000FF);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0xFF0000, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x00FF00, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x0000FF, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x00FF00, FALSE, 0xFFFFFF, FALSE, 0x00FF00);
+	success &= simple_composite_test_one (type, 0xFFFFFF, FALSE, 0xFFFFFF, FALSE, 0xFFFFFF);
+
+	/* Alpha into non-alpha. */
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x000000, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0xFFFFFF, FALSE, 0xFFFFFF);
+	success &= simple_composite_test_one (type, 0x0000007F, TRUE, 0xFFFFFF, FALSE, 0x808080);
+	success &= simple_composite_test_one (type, 0x00000080, TRUE, 0xFFFFFF, FALSE, 0x7F7F7F);
+	success &= simple_composite_test_one (type, 0x000000FF, TRUE, 0xFFFFFF, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0x000000FF, TRUE, 0xFFFFFF, FALSE, 0x000000);
+	success &= simple_composite_test_one (type, 0xFF0000FF, TRUE, 0x000000, FALSE, 0xFF0000);
+	success &= simple_composite_test_one (type, 0x00FF00FF, TRUE, 0x000000, FALSE, 0x00FF00);
+	success &= simple_composite_test_one (type, 0x0000FFFF, TRUE, 0x000000, FALSE, 0x0000FF);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0xFF0000, FALSE, 0xFF0000);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x00FF00, FALSE, 0x00FF00);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x0000FF, FALSE, 0x0000FF);
+	success &= simple_composite_test_one (type, 0x00FF0080, TRUE, 0xFFFFFF, FALSE, 0x7FFF7F);
+	success &= simple_composite_test_one (type, 0xFFFFFFFF, TRUE, 0xFFFFFF, FALSE, 0xFFFFFF);
+
+	/* Non-alpha into alpha. */
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x00000000, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0xFFFFFFFF, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0xFF0000, FALSE, 0x00000000, TRUE, 0xFF0000FF);
+	success &= simple_composite_test_one (type, 0x00FF00, FALSE, 0x00000000, TRUE, 0x00FF00FF);
+	success &= simple_composite_test_one (type, 0x0000FF, FALSE, 0x00000000, TRUE, 0x0000FFFF);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0xFF0000FF, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x00FF00FF, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0x000000, FALSE, 0x0000FFFF, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0x00FF00, FALSE, 0xFFFFFF00, TRUE, 0x00FF00FF);
+	success &= simple_composite_test_one (type, 0xFFFFFF, FALSE, 0xFFFFFFFF, TRUE, 0xFFFFFFFF);
+
+	/* Alpha into alpha. */
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x00000000, TRUE, 0x00000000);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0xFFFFFFFF, TRUE, 0xFFFFFFFF);
+	success &= simple_composite_test_one (type, 0x0000007F, TRUE, 0xFFFFFFFF, TRUE, 0x808080FF);
+	success &= simple_composite_test_one (type, 0x00000080, TRUE, 0xFFFFFFFF, TRUE, 0x7F7F7FFF);
+	success &= simple_composite_test_one (type, 0x000000FF, TRUE, 0xFFFFFFFF, TRUE, 0x000000FF);
+	success &= simple_composite_test_one (type, 0xFF0000FF, TRUE, 0x00000000, TRUE, 0xFF0000FF);
+	success &= simple_composite_test_one (type, 0x00FF00FF, TRUE, 0x00000000, TRUE, 0x00FF00FF);
+	success &= simple_composite_test_one (type, 0x0000FFFF, TRUE, 0x00000000, TRUE, 0x0000FFFF);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0xFF0000FF, TRUE, 0xFF0000FF);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x00FF00FF, TRUE, 0x00FF00FF);
+	success &= simple_composite_test_one (type, 0x00000000, TRUE, 0x0000FFFF, TRUE, 0x0000FFFF);
+	success &= simple_composite_test_one (type, 0x00FF0080, TRUE, 0xFFFFFF00, TRUE, 0x7FFF7F80);
+	success &= simple_composite_test_one (type, 0xFFFFFFFF, TRUE, 0xFFFFFFFF, TRUE, 0xFFFFFFFF);
+
+	return success;
+}
+
+static gboolean
+simple_composite_test (void)
+{
+	gboolean success;
+
+	success = TRUE;
+
+	success &= simple_composite_test_one_type (GDK_INTERP_NEAREST);
+	success &= simple_composite_test_one_type (GDK_INTERP_TILES);
+	success &= simple_composite_test_one_type (GDK_INTERP_BILINEAR);
+	success &= simple_composite_test_one_type (GDK_INTERP_HYPER);
+
+	return success;
+}
+
 int
 main (int argc, char **argv)
 {
+	int result;
+	
+	result = EXIT_SUCCESS;
+
+	/* Run some tests. */
+	if (!simple_composite_test ()) {
+		result = EXIT_FAILURE;
+	}
+
+	return result;
 }