[PATCH xwayland v3] xwayland: Always update the wl_pointer cursor on pointer focus

[Jonas Ådahl]

In Wayland, a client (in this case XWayland) should set the cursor
surface when it receives pointer focus. Not doing this will leave the
curser at whatever it was previously.

When running on XWayland, the X server will not be the entity that
controls what actual pointer cursor is displayed, and it wont be notified
about the pointer cursor changes done by the Wayland compositor. This
causes X11 clients running via XWayland to end up with incorrect pointer
cursors because the X server believes that, if the cursor was previously
set to the cursor C, if we receive Wayland pointer focus over window W
which also has the pointer cursor C, we do not need to update it. This
will cause us to end up with the wrong cursor if cursor C was not the
same one that was already set by the Wayland compositor.

This patch works around this by, when receiving pointer focus, getting
the private mipointer struct changing the "current sprite" pointer to
an invalid cursor in order to trigger the update path next time a cursor
is displayed by dix.

Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
---

This version of the patch doesn't do any API changes, but instead simply
copies private looking parts (MIPOINTER macro) from mipointer.c and pokes
around in the struct behind its back. Personally I think it'd be nicer to
do this via some miPointerInvalidateCursor() call, but that'd mean
extending the API.


Jonas

 hw/xwayland/xwayland-input.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
index 0515eb9..7494e63 100644
--- a/hw/xwayland/xwayland-input.c
+++ b/hw/xwayland/xwayland-input.c
@@ -32,6 +32,14 @@
 #include <xkbsrv.h>
 #include <xserver-properties.h>
 #include <inpututils.h>
+#include <mipointer.h>
+#include <mipointrst.h>
+
+/* Copied from mipointer.c */
+#define MIPOINTER(dev) \
+    (IsFloating(dev) ? \
+        (miPointerPtr)dixLookupPrivate(&(dev)->devPrivates, miPointerPrivKey): \
+        (miPointerPtr)dixLookupPrivate(&(GetMaster(dev, MASTER_POINTER))->devPrivates, miPointerPrivKey))
 
 static void
 xwl_pointer_control(DeviceIntPtr device, PtrCtrl *ctrl)
@@ -210,6 +218,8 @@ pointer_handle_enter(void *data, struct wl_pointer *pointer,
 {
     struct xwl_seat *xwl_seat = data;
     DeviceIntPtr dev = xwl_seat->pointer;
+    DeviceIntPtr master;
+    miPointerPtr mipointer;
     int i;
     int sx = wl_fixed_to_int(sx_w);
     int sy = wl_fixed_to_int(sy_w);
@@ -230,8 +240,18 @@ pointer_handle_enter(void *data, struct wl_pointer *pointer,
 
     xwl_seat->focus_window = wl_surface_get_user_data(surface);
 
+    master = GetMaster(dev, POINTER_OR_FLOAT);
     (*pScreen->SetCursorPosition) (dev, pScreen, sx, sy, TRUE);
-    CheckMotion(NULL, GetMaster(dev, POINTER_OR_FLOAT));
+
+    /* X is very likely to have the wrong idea of what the actual cursor
+     * sprite is, so in order to force updating the cursor lets set the
+     * current sprite to some invalid cursor behind its back so that it
+     * always will think it changed to the not invalid cursor.
+     */
+    mipointer = MIPOINTER(master);
+    mipointer->pSpriteCursor = (CursorPtr) 1;
+
+    CheckMotion(NULL, master);
 
     /* Ideally, X clients shouldn't see these button releases.  When
      * the pointer leaves a window with buttons down, it means that
-- 
2.4.3