[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/include/app.h

@@ -38,6 +38,8 @@ LG_MsgAlert;
 bool app_isRunning(void);
 bool app_inputEnabled(void);
 bool app_isCaptureMode(void);
+bool app_isCaptureOnlyMode(void);
+bool app_isFormatValid(void);
 void app_updateCursorPos(double x, double y);
 void app_updateWindowPos(int x, int y);
 void app_handleResizeEvent(int w, int h, double scale, const struct Border border);

client/include/interface/displayserver.h

@@ -131,10 +131,14 @@ struct LG_DisplayServerOps
   /* dm specific cursor implementations */
   void (*guestPointerUpdated)(double x, double y, int localX, int localY);
   void (*showPointer)(bool show);
-  void (*grabPointer)();
-  void (*ungrabPointer)();
   void (*grabKeyboard)();
   void (*ungrabKeyboard)();
+  /* (un)grabPointer is used to toggle cursor tracking/confine in normal mode */
+  void (*grabPointer)();
+  void (*ungrabPointer)();
+  /* (un)capturePointer is used do toggle special cursor tracking in capture mode */
+  void (*capturePointer)();
+  void (*uncapturePointer)();
 
   /* exiting = true if the warp is to leave the window */
   void (*warpPointer)(int x, int y, bool exiting);
@@ -199,6 +203,8 @@ struct LG_DisplayServerOps
   assert((x)->showPointer        ); \
   assert((x)->grabPointer        ); \
   assert((x)->ungrabPointer      ); \
+  assert((x)->capturePointer     ); \
+  assert((x)->uncapturePointer   ); \
   assert((x)->warpPointer        ); \
   assert((x)->realignPointer     ); \
   assert((x)->isValidPointerPos  ); \