tests: Add capture_screenshot_of_output()

Provides a convenience function for JFDI grabbing of a single
screenshot.  Tests that are doing multiple screenshots or other
fanciness probably will bypass this routine and do things more manually,
but this'll provide a reference implementation.  And hopefully there'll
be enough simple cases that this actually is useful.

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-By: Derek Foreman <derekf@osg.samsung.com>

tests/internal-screenshot-test.c

@@ -141,38 +141,29 @@ create_screenshot_surface(struct client *client) {
 	return screenshot;
 }
 
-TEST(internal_screenshot)
-{
-	struct client *client;
-	struct surface *screenshot = NULL;
-	struct surface *reference = NULL;
-	struct rectangle clip;
-	const char *fname;
-	bool match = false;
-	bool dump_all_images = true;
-
-	printf("Starting test\n");
-
-	/* Create the client */
-	client = create_client_and_test_surface(100, 100, 100, 100);
-	assert(client);
-	printf("Client created\n");
+/** capture_screenshot_of_output()
+ *
+ * Requests a screenshot from the server of the output that the
+ * client appears on.  The image data returned from the server
+ * can be accessed from the screenshot surface's data member.
+ *
+ * @returns a new surface object, which should be free'd when no
+ * longer needed.
+ */
+static struct surface *
+capture_screenshot_of_output(struct client *client) {
+	struct surface *screenshot;
 
 	/* Create a surface to hold the screenshot */
 	screenshot = create_screenshot_surface(client);
-	assert(screenshot);
-	printf("Screenshot buffer created and attached to surface\n");
 
-	/* Take a snapshot.  Result will be in screenshot->wl_buffer. */
 	client->test->buffer_copy_done = 0;
 	weston_test_capture_screenshot(client->test->weston_test,
 				       client->output->wl_output,
 				       screenshot->wl_buffer);
-	printf("Capture request sent\n");
 	while (client->test->buffer_copy_done == 0)
 		if (wl_display_dispatch(client->wl_display) < 0)
 			break;
-	printf("Roundtrip done\n");
 
 	/* FIXME: Document somewhere the orientation the screenshot is taken
 	 * and how the clip coords are interpreted, in case of scaling/transform.
@@ -180,6 +171,29 @@ TEST(internal_screenshot)
 	 * Protocol docs in the XML, comparison function docs in Doxygen style.
 	 */
 
+	return screenshot;
+}
+
+TEST(internal_screenshot)
+{
+	struct client *client;
+	struct surface *screenshot = NULL;
+	struct surface *reference = NULL;
+	struct rectangle clip;
+	const char *fname;
+	bool match = false;
+	bool dump_all_images = true;
+
+	/* Create the client */
+	printf("Creating client for test\n");
+	client = create_client_and_test_surface(100, 100, 100, 100);
+	assert(client);
+
+	/* Take a snapshot.  Result will be in screenshot->wl_buffer. */
+	printf("Taking a screenshot\n");
+	screenshot = capture_screenshot_of_output(client);
+	assert(screenshot);
+
 	/* Load reference image */
 	fname = screenshot_reference_filename("internal-screenshot", 0);
 	printf("Loading reference image %s\n", fname);