xcb: Query the display's subpixel order via RENDER

With commit e691d242, the xcb backend started parsing the resources, just like
cairo-xlib does. One behavior from cairo-xlib was missing: If no Xft.rgba
property was specified, cairo-xlib defaults to the screen's subpixel order.
This commit brings that last bit of functionality to cairo-xcb (but currently
disabled due to commit e0c0a673).

This commits adds a new array to cairo_xcb_connection_t that contains the
subpixel order for each screen. There is also a new member in cairo_xcb_screen_t
which contains the subpixel order of that screen and which is initialized from
the array when the screen is constructed. With this in place, the
resource-parsing code can just pick the subpixel order from the screen if
needed.

Signed-off-by: Uli Schlachter <psychon@znc.in>

1 files changed, 19 insertions, 0 deletions

diff --git a/src/cairo-xcb-connection.c b/src/cairo-xcb-connection.c
index 2d51e1449..67897fa4e 100644
--- a/src/cairo-xcb-connection.c
+++ b/src/cairo-xcb-connection.c
@@ -79,6 +79,7 @@ typedef struct _cairo_xcb_xid {
 #define XCB_RENDER_HAS_FILTERS(surface)			XCB_RENDER_AT_LEAST((surface), 0, 6)
 #define XCB_RENDER_HAS_FILTER_GOOD(surface) FALSE
 #define XCB_RENDER_HAS_FILTER_BEST(surface) FALSE
+#define XCB_RENDER_HAS_SUBPIXEL_ORDER(surface)		XCB_RENDER_AT_LEAST((surface), 0, 6)
 
 #define XCB_RENDER_HAS_EXTENDED_REPEAT(surface)	XCB_RENDER_AT_LEAST((surface), 0, 10)
 #define XCB_RENDER_HAS_GRADIENTS(surface)	XCB_RENDER_AT_LEAST((surface), 0, 10)
@@ -407,6 +408,15 @@ _cairo_xcb_connection_query_render (cairo_xcb_connection_t *connection)
     if (XCB_RENDER_HAS_GRADIENTS (version))
 	connection->flags |= CAIRO_XCB_RENDER_HAS_GRADIENTS;
 
+    if (XCB_RENDER_HAS_SUBPIXEL_ORDER (version)) {
+	uint32_t screen;
+	uint32_t *subpixel = xcb_render_query_pict_formats_subpixels(formats);
+
+	/* The spec explicitly allows to have too few entries in the reply... */
+	for (screen = 0; screen < formats->num_subpixel && screen < connection->root->roots_len; screen++)
+	    connection->subpixel_orders[screen] = subpixel[screen];
+    }
+
     free (version);
 
     status = _cairo_xcb_connection_parse_xrender_formats (connection, formats);
@@ -581,6 +591,7 @@ _device_destroy (void *device)
     CAIRO_MUTEX_FINI (connection->shm_mutex);
     CAIRO_MUTEX_FINI (connection->screens_mutex);
 
+    free (connection->subpixel_orders);
     free (connection);
 }
 
@@ -684,6 +695,14 @@ _cairo_xcb_connection_get (xcb_connection_t *xcb_connection)
 
     connection->root = xcb_get_setup (xcb_connection);
     connection->render = NULL;
+    connection->subpixel_orders = calloc (connection->root->roots_len, sizeof(*connection->subpixel_orders));
+    if (unlikely (connection->subpixel_orders == NULL)) {
+	CAIRO_MUTEX_UNLOCK (connection->device.mutex);
+	_cairo_xcb_connection_destroy (connection);
+	connection = NULL;
+	goto unlock;
+    }
+
     ext = xcb_get_extension_data (xcb_connection, &xcb_render_id);
     if (ext != NULL && ext->present) {
 	status = _cairo_xcb_connection_query_render (connection);