From 5880cc2a041db061f8d546a0725f1dcaac3902dd Mon Sep 17 00:00:00 2001
From: nanahi <130121847+na-na-hi@users.noreply.github.com>
Date: Sat, 10 Feb 2024 14:43:50 -0500
Subject: [PATCH] x11_common: handle window dragging in ButtonPress event

Begin the _NET_WM_MOVERESIZE window dragging in ButtonPress event
to match the behavior of win32 and wayland, simplify logic by dropping
the win_drag_button1_down hack required by the old method, and fix a race
condition described in commit 19f101db680f966a6e56035a16784541be390982,
which happens when moving the mouse and releasing the button at the same time.

The race condition can be easily triggered when using a touch screen
(tested with libinput driver), where a tap is translated to MotionNotify,
ButtonPress, MotionNotify, and ButtonRelease in sequence, with the last 2
events having the same timestamp. This has caused some window managers to
not stop dragging after the ButtonRelease, resulting in window being stuck
in dragging state after a single tap.
---
 video/out/x11_common.c | 42 +++++++++++++++++-------------------------
 video/out/x11_common.h |  3 ---
 2 files changed, 17 insertions(+), 28 deletions(-)

diff --git a/video/out/x11_common.c b/video/out/x11_common.c
index 088e0ac34f900..30c34eb6e92da 100644
--- a/video/out/x11_common.c
+++ b/video/out/x11_common.c
@@ -1217,7 +1217,6 @@ static void release_all_keys(struct vo *vo)
 
     if (x11->no_autorepeat)
         mp_input_put_key(x11->input_ctx, MP_INPUT_RELEASE_ALL);
-    x11->win_drag_button1_down = false;
 }
 
 void vo_x11_check_events(struct vo *vo)
@@ -1288,30 +1287,12 @@ void vo_x11_check_events(struct vo *vo)
             release_all_keys(vo);
             break;
         case MotionNotify:
-            if (x11->win_drag_button1_down && !x11->fs &&
-                !mp_input_test_dragging(x11->input_ctx, Event.xmotion.x,
-                                                        Event.xmotion.y))
-            {
-                mp_input_put_key(x11->input_ctx, MP_INPUT_RELEASE_ALL);
-                XUngrabPointer(x11->display, CurrentTime);
-
-                long params[5] = {
-                    Event.xmotion.x_root, Event.xmotion.y_root,
-                    8, // _NET_WM_MOVERESIZE_MOVE
-                    1, // button 1
-                    1, // source indication: normal
-                };
-                x11_send_ewmh_msg(x11, "_NET_WM_MOVERESIZE", params);
-            } else {
-                mp_input_set_mouse_pos(x11->input_ctx, Event.xmotion.x,
-                                                       Event.xmotion.y);
-            }
-            x11->win_drag_button1_down = false;
+            mp_input_set_mouse_pos(x11->input_ctx, Event.xmotion.x,
+                                                   Event.xmotion.y);
             break;
         case LeaveNotify:
             if (Event.xcrossing.mode != NotifyNormal)
                 break;
-            x11->win_drag_button1_down = false;
             mp_input_put_key(x11->input_ctx, MP_KEY_MOUSE_LEAVE);
             break;
         case EnterNotify:
@@ -1322,19 +1303,30 @@ void vo_x11_check_events(struct vo *vo)
         case ButtonPress:
             if (Event.xbutton.button - 1 >= MP_KEY_MOUSE_BTN_COUNT)
                 break;
-            if (Event.xbutton.button == 1)
-                x11->win_drag_button1_down = true;
             mp_input_put_key(x11->input_ctx,
                              (MP_MBTN_BASE + Event.xbutton.button - 1) |
                              get_mods(Event.xbutton.state) | MP_KEY_STATE_DOWN);
             long msg[4] = {XEMBED_REQUEST_FOCUS};
             vo_x11_xembed_send_message(x11, msg);
+            if (Event.xbutton.button == 1 && !x11->fs &&
+                !mp_input_test_dragging(x11->input_ctx, Event.xmotion.x,
+                                                        Event.xmotion.y))
+            {
+                mp_input_put_key(x11->input_ctx, MP_INPUT_RELEASE_ALL);
+                XUngrabPointer(x11->display, CurrentTime);
+
+                long params[5] = {
+                    Event.xmotion.x_root, Event.xmotion.y_root,
+                    8, // _NET_WM_MOVERESIZE_MOVE
+                    1, // button 1
+                    1, // source indication: normal
+                };
+                x11_send_ewmh_msg(x11, "_NET_WM_MOVERESIZE", params);
+            }
             break;
         case ButtonRelease:
             if (Event.xbutton.button - 1 >= MP_KEY_MOUSE_BTN_COUNT)
                 break;
-            if (Event.xbutton.button == 1)
-                x11->win_drag_button1_down = false;
             mp_input_put_key(x11->input_ctx,
                              (MP_MBTN_BASE + Event.xbutton.button - 1) |
                              get_mods(Event.xbutton.state) | MP_KEY_STATE_UP);
diff --git a/video/out/x11_common.h b/video/out/x11_common.h
index 8587c452c676f..d88c8899c8b27 100644
--- a/video/out/x11_common.h
+++ b/video/out/x11_common.h
@@ -137,9 +137,6 @@ struct vo_x11_state {
     Atom dnd_requested_action;
     Window dnd_src_window;
 
-    /* dragging the window */
-    bool win_drag_button1_down;
-
     Atom icc_profile_property;
 };