clients: Fix weston-scaler source-only mode to use integer width and height

If only the source of a viewport is set, the width and height must
be integer or the protocol mandates that the compositor generate an
error.  This is because using only the source is a crop, and the
width and height become the surface size - all surface sizes must
be integer.

Weston was fixed to generate this error in bb32ccc0, however the
test app continued to use fractional co-ordinates when run as
weston-scaler -s  (which only sets the viewport source)

This leaves fractional width/height for the other cases, but uses
integer for the crop-only mode.  The descriptions in the help text
are still accurate with this change, but weston-scaler -s no longer
exits with an error.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

clients/scaler.c

@@ -86,6 +86,16 @@ set_my_viewport(struct box *box)
 
 	switch (box->mode){
 	case MODE_SRC_ONLY:
+		/* In SRC_ONLY mode we're just cropping - in order
+		 * for the surface size to remain an integer, the
+		 * compositor will generate an error if we use a
+		 * fractional width or height.
+		 *
+		 * We use fractional width/height for the other cases
+		 * to ensure fractional values are still tested.
+		 */
+		src_width = wl_fixed_from_int(RECT_W / BUFFER_SCALE);
+		src_height = wl_fixed_from_int(RECT_H / BUFFER_SCALE);
 		wp_viewport_set_source(box->viewport, src_x, src_y,
 				       src_width, src_height);
 		break;