Make show_image() cope with more formats

This makes show_image() deal with more formats than just a8r8g8b8, in
particular, a8r8g8b8_sRGB can now be handled.

Images that are passed to show_image with a format of a8r8g8b8_sRGB
are displayed without modification under the assumption that the
monitor is approximately sRGB.

Images with a format of a8r8g8b8 are also displayed without
modification since many other users of show_image() have been
generating essentially sRGB data with this format. Other formats are
also assumed to be gamma compressed; these are converted to a8r8g8b8
before being displayed.

With these changes, srgb-test.c doesn't need to do its own conversion
anymore.

demos/composite-test.c

@@ -149,7 +149,7 @@ main (int argc, char **argv)
 				0, 0, 0, 0, 0, 0, WIDTH, HEIGHT);
 	pixman_image_composite (operators[i].op, parrot, NULL, dest_img,
 				0, 0, 0, 0, 0, 0, WIDTH, HEIGHT);
-	pixbuf = pixbuf_from_argb32 (pixman_image_get_data (dest_img), TRUE,
+	pixbuf = pixbuf_from_argb32 (pixman_image_get_data (dest_img),
 				     WIDTH, HEIGHT, WIDTH * 4);
 	image = gtk_image_new_from_pixbuf (pixbuf);
 	gtk_box_pack_start (GTK_BOX (vbox), image, FALSE, FALSE, 0);

demos/gtk-utils.c

@@ -5,7 +5,6 @@
 
 GdkPixbuf *
 pixbuf_from_argb32 (uint32_t *bits,
-		    gboolean has_alpha,
 		    int width,
 		    int height,
 		    int stride)
@@ -47,12 +46,12 @@ show_image (pixman_image_t *image)
 {
     GtkWidget *window;
     GdkPixbuf *pixbuf;
-    int width, height, stride;
+    int width, height;
     int argc;
     char **argv;
     char *arg0 = g_strdup ("pixman-test-program");
-    gboolean has_alpha;
     pixman_format_code_t format;
+    pixman_image_t *copy;
 
     argc = 1;
     argv = (char **)&arg0;
@@ -62,21 +61,43 @@ show_image (pixman_image_t *image)
     window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
     width = pixman_image_get_width (image);
     height = pixman_image_get_height (image);
-    stride = pixman_image_get_stride (image);
 
     gtk_window_set_default_size (GTK_WINDOW (window), width, height);
-    
+
     format = pixman_image_get_format (image);
-    
-    if (format == PIXMAN_a8r8g8b8)
-	has_alpha = TRUE;
-    else if (format == PIXMAN_x8r8g8b8)
-	has_alpha = FALSE;
-    else
-	g_error ("Can't deal with this format: %x\n", format);
-    
-    pixbuf = pixbuf_from_argb32 (pixman_image_get_data (image), has_alpha,
-				 width, height, stride);
+
+    /* Three cases:
+     *
+     *  - image is a8r8g8b8_sRGB: we will display without modification
+     *    under the assumption that the monitor is sRGB
+     *
+     *  - image is a8r8g8b8: we will display without modification
+     *    under the assumption that whoever created the image
+     *    probably did it wrong by using sRGB inputs
+     *
+     *  - other: we will convert to a8r8g8b8 under the assumption that
+     *    whoever created the image probably did it wrong.
+     */
+    switch (format)
+    {
+    case PIXMAN_a8r8g8b8_sRGB:
+    case PIXMAN_a8r8g8b8:
+	copy = pixman_image_ref (image);
+	break;
+
+    default:
+	copy = pixman_image_create_bits (PIXMAN_a8r8g8b8,
+					 width, height, NULL, -1);
+	pixman_image_composite32 (PIXMAN_OP_SRC,
+				  image, NULL, copy,
+				  0, 0, 0, 0, 0, 0,
+				  width, height);
+	break;
+    }
+
+    pixbuf = pixbuf_from_argb32 (pixman_image_get_data (copy),
+				 width, height,
+				 pixman_image_get_stride (copy));
     
     g_signal_connect (window, "expose_event", G_CALLBACK (on_expose), pixbuf);
     g_signal_connect (window, "delete_event", G_CALLBACK (gtk_main_quit), NULL);

demos/gtk-utils.h

@@ -7,7 +7,6 @@
 void show_image (pixman_image_t *image);
 
 GdkPixbuf *pixbuf_from_argb32 (uint32_t *bits,
-		               gboolean has_alpha,
                                int width,
                                int height,
                                int stride);

demos/srgb-test.c

@@ -79,15 +79,6 @@ main (int argc, char **argv)
     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);