Avoid extra sync when fetching DND proxy window

* src/xterm.c (x_dnd_get_proxy_proto): New function.
(x_dnd_get_target_window): Use it on XCB to determine window
proxy and proto for toplevel window.

1 files changed, 74 insertions, 1 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 97dfbc5add1..443009c0dba 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -1343,9 +1343,76 @@ x_dnd_compute_toplevels (struct x_display_info *dpyinfo)
 
 #define X_DND_SUPPORTED_VERSION 5
 
+
 static int x_dnd_get_window_proto (struct x_display_info *, Window);
 static Window x_dnd_get_window_proxy (struct x_display_info *, Window);
 
+#ifdef USE_XCB
+static void
+x_dnd_get_proxy_proto (struct x_display_info *dpyinfo, Window wdesc,
+                       Window *proxy_out, int *proto_out)
+{
+  xcb_get_property_cookie_t xdnd_proto_cookie;
+  xcb_get_property_cookie_t xdnd_proxy_cookie;
+  xcb_get_property_reply_t *reply;
+  xcb_generic_error_t *error;
+
+  if (proxy_out)
+    *proxy_out = None;
+
+  if (proto_out)
+    *proto_out = -1;
+
+  if (proxy_out)
+    xdnd_proxy_cookie = xcb_get_property (dpyinfo->xcb_connection, 0,
+                                          (xcb_window_t) wdesc,
+                                          (xcb_atom_t) dpyinfo->Xatom_XdndProxy,
+                                          XCB_ATOM_WINDOW, 0, 1);
+
+  if (proto_out)
+    xdnd_proto_cookie = xcb_get_property (dpyinfo->xcb_connection, 0,
+                                          (xcb_window_t) wdesc,
+                                          (xcb_atom_t) dpyinfo->Xatom_XdndAware,
+                                          XCB_ATOM_ATOM, 0, 1);
+
+  if (proxy_out)
+    {
+      reply = xcb_get_property_reply (dpyinfo->xcb_connection,
+                                      xdnd_proxy_cookie, &error);
+
+      if (!reply)
+        free (error);
+      else
+        {
+          if (reply->format == 32
+              && reply->type == XCB_ATOM_WINDOW
+              && (xcb_get_property_value_length (reply) >= 4))
+            *proxy_out = *(xcb_window_t *) xcb_get_property_value (reply);
+
+          free (reply);
+        }
+    }
+
+  if (proto_out)
+    {
+      reply = xcb_get_property_reply (dpyinfo->xcb_connection,
+                                      xdnd_proto_cookie, &error);
+
+      if (!reply)
+        free (error);
+      else
+        {
+          if (reply->format == 32
+              && reply->type == XCB_ATOM_ATOM
+              && (xcb_get_property_value_length (reply) >= 4))
+            *proto_out = (int) *(xcb_atom_t *) xcb_get_property_value (reply);
+
+          free (reply);
+        }
+    }
+}
+#endif
+
 #ifdef HAVE_XSHAPE
 static bool
 x_dnd_get_target_window_2 (XRectangle *rects, int nrects,
@@ -1433,7 +1500,11 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
 
       if (child != None)
         {
-          proxy = x_dnd_get_window_proxy (dpyinfo, child_return);
+#ifndef USE_XCB
+          proxy = x_dnd_get_window_proxy (dpyinfo, child);
+#else
+          x_dnd_get_proxy_proto (dpyinfo, child, &proxy, proto_out);
+#endif
 
           if (proxy != None)
             {
@@ -1446,7 +1517,9 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
                 }
             }
 
+#ifndef USE_XCB
           *proto_out = x_dnd_get_window_proto (dpyinfo, child);
+#endif
           return child;
         }