tests/internal-screenshot: use image-iter.h

Simplify the code by using ready-made helpers.

This also change the loop to draw the image row by row rather than
column by column. Row by row is more natural as it is linear with the
memory layout. No other change in behaviour.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

tests/internal-screenshot-test.c

@@ -30,6 +30,7 @@
 
 #include "weston-test-client-helper.h"
 #include "weston-test-fixture-compositor.h"
+#include "image-iter.h"
 #include "test-config.h"
 
 static enum test_result_code
@@ -55,31 +56,21 @@ DECLARE_FIXTURE_SETUP(fixture_setup);
 static void
 draw_stuff(pixman_image_t *image)
 {
-	int w, h;
-	int stride; /* bytes */
+	struct image_header ih = image_header_from(image);
 	int x, y;
 	uint32_t r, g, b;
-	uint32_t *pixels;
-	uint32_t *pixel;
-	pixman_format_code_t fmt;
 
-	fmt = pixman_image_get_format(image);
-	w = pixman_image_get_width(image);
-	h = pixman_image_get_height(image);
-	stride = pixman_image_get_stride(image);
-	pixels = pixman_image_get_data(image);
+	for (y = 0; y < ih.height; y++) {
+		uint32_t *pixel = image_header_get_row_u32(&ih, y);
 
-	assert(PIXMAN_FORMAT_BPP(fmt) == 32);
-
-	for (x = 0; x < w; x++)
-		for (y = 0; y < h; y++) {
+		for (x = 0; x < ih.width; x++, pixel++) {
 			b = x;
 			g = x + y;
 			r = y;
-			pixel = pixels + (y * stride / 4) + x;
 			*pixel = (255U << 24) | (r << 16) | (g << 8) | b;
 		}
 	}
+}
 
 TEST(internal_screenshot)
 {