[Pixman] [PATCH 2/3] test/utils.c: Rename and export the pngify_pixels() function.

[Søren Sandmann]

From: Søren Sandmann Pedersen <ssp at redhat.com>

This function converts from a8r8g8b8 to non-premultiplied RGBA (the
PNG or GdkPixbuf format that has the channels in this order: R, G, B,
A in memory regardless of the computer's endianness). The function's
new name is a8r8g8b8_to_rgba_np().
---
 test/utils.c |   22 +++++++++++-----------
 test/utils.h |    9 +++++++++
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/test/utils.c b/test/utils.c
index 379bd71..cc0365a 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -340,17 +340,15 @@ make_random_bytes (int n_bytes)
     return bytes;
 }
 
-#ifdef HAVE_LIBPNG
-
-static void
-pngify_pixels (uint32_t *pixels, int n_pixels)
+void
+a8r8g8b8_to_rgba_np (uint32_t *dst, uint32_t *src, int n_pixels)
 {
+    uint8_t *dst8 = (uint8_t *)dst;
     int i;
 
     for (i = 0; i < n_pixels; ++i)
     {
-	uint32_t p = pixels[i];
-	uint8_t *out = (uint8_t *)&(pixels[i]);
+	uint32_t p = src[i];
 	uint8_t a, r, g, b;
 
 	a = (p & 0xff000000) >> 24;
@@ -365,13 +363,15 @@ pngify_pixels (uint32_t *pixels, int n_pixels)
 	    b = (b * 255) / a;
 	}
 
-	*out++ = r;
-	*out++ = g;
-	*out++ = b;
-	*out++ = a;
+	*dst8++ = r;
+	*dst8++ = g;
+	*dst8++ = b;
+	*dst8++ = a;
     }
 }
 
+#ifdef HAVE_LIBPNG
+
 pixman_bool_t
 write_png (pixman_image_t *image, const char *filename)
 {
@@ -398,7 +398,7 @@ write_png (pixman_image_t *image, const char *filename)
     pixman_image_composite32 (
 	PIXMAN_OP_SRC, image, NULL, copy, 0, 0, 0, 0, 0, 0, width, height);
 
-    pngify_pixels (data, height * width);
+    a8r8g8b8_to_rgba_np (data, data, height * width);
 
     for (i = 0; i < height; ++i)
 	row_pointers[i] = (png_bytep)(data + i * width);
diff --git a/test/utils.h b/test/utils.h
index 3c0647b..01af316 100644
--- a/test/utils.h
+++ b/test/utils.h
@@ -107,6 +107,15 @@ fail_after (int seconds, const char *msg);
 /* If possible, enable traps for floating point exceptions */
 void enable_fp_exceptions(void);
 
+/* Converts a8r8g8b8 pixels to pixels that
+ *  - are not premultiplied,
+ *  - are stored in this order in memory: R, G, B, A, regardless of
+ *    the endianness of the computer.
+ * It is allowed for @src and @dst to point to the same memory buffer.
+ */
+void
+a8r8g8b8_to_rgba_np (uint32_t *dst, uint32_t *src, int n_pixels);
+
 pixman_bool_t
 write_png (pixman_image_t *image, const char *filename);
 
-- 
1.7.4