[client] ds: separate grab and capture logic

Currently, (un)grabPointer is used both for tracking/confining the mouse
in normal mode, as well as entering/exiting capture mode. This makes it
impossible to use separate cursor logic for capture mode, which is needed
to deal with overlapping windows for the Wayland backend.

This commit creates separate (un)capturePointer for entering/exiting
capture mode. There should be no behaviour changes.

client/displayservers/X11/x11.c

@@ -1063,6 +1063,23 @@ static void x11UngrabPointer(void)
   x11.pointerGrabbed = false;
 }
 
+static void x11CapturePointer(void)
+{
+  x11GrabPointer();
+}
+
+static void x11UncapturePointer(void)
+{
+  /* we need to ungrab the pointer on the following conditions when exiting capture mode:
+   *   - if the format is invalid as we do not know where the guest cursor is,
+   *     which breaks edge detection as the cursor can not be warped out of the
+   *     window when we release it.
+   *   - if the user has opted to use captureInputOnly mode.
+   */
+  if (!app_isFormatValid() || app_isCaptureOnlyMode())
+    x11UngrabPointer();
+}
+
 static void x11GrabKeyboard(void)
 {
   if (x11.keyboardGrabbed)
@@ -1224,6 +1241,8 @@ struct LG_DisplayServerOps LGDS_X11 =
   .showPointer         = x11ShowPointer,
   .grabPointer         = x11GrabPointer,
   .ungrabPointer       = x11UngrabPointer,
+  .capturePointer      = x11CapturePointer,
+  .uncapturePointer    = x11UncapturePointer,
   .grabKeyboard        = x11GrabKeyboard,
   .ungrabKeyboard      = x11UngrabKeyboard,
   .warpPointer         = x11WarpPointer,