fix: the touchpad moves a game's own cursor when it locks the pointer (#772)

app/src/main/cpp/waylandcomp/src/compositor.c

@@ -2194,6 +2194,7 @@ struct constraint {
     int pending_region_set;
     int hint_set, pending_hint_set;
     double hint_x, hint_y, pending_hint_x, pending_hint_y;
+    int gave_keys;
 };
 static struct wl_list g_constraints;
 static struct constraint *g_active_constraint;
@@ -2272,6 +2273,14 @@ static void constraint_end(struct constraint *k, int tell_client, const char *wh
         g_ptr_y = oy + k->hint_y;
     }
     g_raw_valid = 0;
+    if (k->gave_keys) {
+        k->gave_keys = 0;
+        for (int i = 0; i < g_nkbs; i++) {
+            if (!k->surface || g_kbs[i].focus != k->surface->resource) continue;
+            wl_keyboard_send_leave(g_kbs[i].kb, wl_display_next_serial(g_display), g_kbs[i].focus);
+            g_kbs[i].focus = NULL;
+        }
+    }
     if (tell_client) constraint_send_state(k, 0);
     constraint_describe(k, name, sizeof(name));
     droiddeck_log("pointer", "%s: %s (%s), pointer at %d,%d", k->is_lock ? "unlocked" : "unconfined",
@@ -2290,6 +2299,12 @@ static void constraint_activate(struct constraint *k) {
     if (!k->is_lock) confine_clamp(k, &g_ptr_x, &g_ptr_y);
     constraint_origin(k, &ox, &oy);
     pointer_focus(k->surface->resource, wl_fixed_from_double(g_ptr_x - ox), wl_fixed_from_double(g_ptr_y - oy));
+    int focused = 0;
+    for (int i = 0; i < g_nkbs; i++) if (g_kbs[i].focus) focused = 1;
+    if (k->is_lock && !focused && keyboard_for(wl_resource_get_client(k->surface->resource))) {
+        keyboard_focus(k->surface->resource);
+        k->gave_keys = 1;
+    }
     constraint_send_state(k, 1);
     constraint_describe(k, name, sizeof(name));
     if (k->is_lock)

app/src/main/java/com/droiddeck/launcher/SessionActivity.kt

@@ -177,6 +177,11 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
             if (pointerLocked == locked) return@post
             pointerLocked = locked
             Log.i(TAG, "pointer lock " + if (locked) "taken by a program" else "released")
+            // Touchpad deltas are measured from the middle while locked (moveLockedPointer).
+            if (locked && ::touchpad.isInitialized) {
+                drawnRect()?.let { touchpad.place(it.centerX(), it.centerY()) }
+                cursorVisible = false
+            }
             updatePointerCapture()
         }
     }
@@ -1705,9 +1710,11 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
     }
 
     private val pointerListener = object : PointerGestures.Listener {
-        override fun onMove(x: Float, y: Float) = movePointer(x, y)
+        override fun onMove(x: Float, y: Float) {
+            if (pointerLocked) moveLockedPointer(x, y) else movePointer(x, y)
+        }
         override fun onButton(button: Int, pressed: Boolean, x: Float, y: Float) {
-            movePointer(x, y)
+            if (!pointerLocked) movePointer(x, y)
             WaylandCompositor.nativeSendSceneInput(3, button, if (pressed) 1 else 0)
         }
         override fun onWheel(steps: Int) { WaylandCompositor.nativeSendSceneInput(4, steps, 0) }
@@ -1717,6 +1724,14 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
         }
     }
 
+    private fun moveLockedPointer(x: Float, y: Float) {
+        val rect = drawnRect() ?: return
+        val scale = SessionState.outputSize.first / rect.width()
+        WaylandCompositor.sendPointerDelta((x - rect.centerX()) * scale, (y - rect.centerY()) * scale)
+        touchpad.place(rect.centerX(), rect.centerY())
+        cursorVisible = false
+    }
+
     private fun movePointer(x: Float, y: Float) {
         val rect = drawnRect() ?: return
         val cx = x.coerceIn(rect.left, rect.right)