Remove redeundant -rgb24-ref.png images.

In several cases the -rgb24 reference images were identical to the -ref images.
So we change the logic to find the latter if the former doesn't exist, and then
we remove the redundant images.

test/cairo-test.c

@@ -85,7 +85,7 @@ static const char *fail_face = "", *normal_face = "";
 /* Static data is messy, but we're coding for tests here, not a
  * general-purpose library, and it keeps the tests cleaner to avoid a
  * context object there, (though not a whole lot). */
-FILE *cairo_test_log_file;
+FILE *cairo_test_log_file = NULL;
 
 void
 cairo_test_init (const char *test_name)
@@ -107,9 +107,10 @@ void
 cairo_test_log (const char *fmt, ...)
 {
     va_list va;
+    FILE *file = cairo_test_log_file ? cairo_test_log_file : stderr;
 
     va_start (va, fmt);
-    vfprintf (cairo_test_log_file, fmt, va);
+    vfprintf (file, fmt, va);
     va_end (va);
 }
 
@@ -1422,6 +1423,7 @@ cairo_test_for_target (cairo_test_t *test,
 	srcdir = ".";
     format = _cairo_test_content_name (target->content);
     
+    /* First look for a target/format-specific reference image. */
     xasprintf (&png_name, "%s-%s-%s%s", test->name,
 	       target->name, format, CAIRO_TEST_PNG_SUFFIX);
     xasprintf (&ref_name, "%s/%s-%s-%s%s", srcdir, test->name,
@@ -1429,13 +1431,17 @@ cairo_test_for_target (cairo_test_t *test,
     if (access (ref_name, F_OK) != 0) {
 	free (ref_name);
 
-	if (target->content == CAIRO_CONTENT_COLOR_ALPHA ||
-	    target->content == CAIRO_TEST_CONTENT_COLOR_ALPHA_FLATTENED)
+	/* Next, look for format-specifc reference image. */
+	xasprintf (&ref_name, "%s/%s-%s%s", srcdir, test->name,
+		   format,CAIRO_TEST_REF_SUFFIX);
+
+	if (access (ref_name, F_OK) != 0) {
+	    free (ref_name);
+
+	    /* Finally, look for the standard reference image. */
 	    xasprintf (&ref_name, "%s/%s%s", srcdir, test->name,
 		       CAIRO_TEST_REF_SUFFIX);
-	else
-	    xasprintf (&ref_name, "%s/%s-%s%s", srcdir, test->name,
-		       format,CAIRO_TEST_REF_SUFFIX);
+	}
     }
     xasprintf (&diff_name, "%s-%s-%s%s", test->name,
 	       target->name, format, CAIRO_TEST_DIFF_SUFFIX);

test/imagediff.c

@@ -34,6 +34,7 @@
 int 
 main (int argc, char *argv[])
 {
+    read_png_status_t status;
     unsigned char *buffer_a;
     unsigned int width_a, height_a, stride_a;
     unsigned char *buffer_b;
@@ -51,8 +52,13 @@ main (int argc, char *argv[])
 	exit (1);
     }
 
-    read_png_argb32 (argv[1], &buffer_a, &width_a, &height_a, &stride_a);
-    read_png_argb32 (argv[2], &buffer_b, &width_b, &height_b, &stride_b);
+    status = read_png_argb32 (argv[1], &buffer_a, &width_a, &height_a, &stride_a);
+    if (status)
+	return 1;
+
+    status = read_png_argb32 (argv[2], &buffer_b, &width_b, &height_b, &stride_b);
+    if (status)
+	return 1;
 
     if ((width_a == width_b) && (height_a == height_b) && (stride_a == stride_b))
     {
@@ -77,8 +83,5 @@ main (int argc, char *argv[])
 
     free (buffer);
 
-    return total_pixels_changed;
+    return (total_pixels_changed != 0);
 }
-
-
-