Wayland: Implement ridiculous workaround for broken dnd

Wayland is *the worst* window system I have ever had the
displeasure of trying to support.

glfw/glfw3.h

@@ -4984,7 +4984,7 @@ GLFWAPI GLFWdragsourcefun glfwSetDragSourceCallback(GLFWwindow* window, GLFWdrag
 // Start a drag. If called with operations == -1 indicates that previously
 // requested data via GLFW_DRAG_DATA_REQUEST is ready. operations == -2 means
 // that the drag image is changed.
-GLFWAPI int glfwStartDrag(GLFWwindow* window, const GLFWDragSourceItem *items, size_t mime_count, const GLFWimage* thumbnail, int operations);
+GLFWAPI int glfwStartDrag(GLFWwindow* window, const GLFWDragSourceItem *items, size_t mime_count, const GLFWimage* thumbnail, int operations, bool needs_toplevel_on_wayland);
 
 /*! @brief Returns whether the specified joystick is present.
  *

glfw/input.c

@@ -1161,7 +1161,7 @@ _glfwFreeDragSourceData(void) {
 }
 
 GLFWAPI int
-glfwStartDrag(GLFWwindow* handle, const GLFWDragSourceItem *items, size_t item_count, const GLFWimage* thumbnail, int operations) {
+glfwStartDrag(GLFWwindow* handle, const GLFWDragSourceItem *items, size_t item_count, const GLFWimage* thumbnail, int operations, bool needs_toplevel_on_wayland) {
     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);
     _GLFW_REQUIRE_INIT_OR_RETURN(EINVAL);
@@ -1188,6 +1188,7 @@ glfwStartDrag(GLFWwindow* handle, const GLFWDragSourceItem *items, size_t item_c
     }
     _glfw.drag.window_id = window->id;
     _glfw.drag.operations = operations;
+    _glfw.drag.needs_toplevel_on_wayland = needs_toplevel_on_wayland;
     int ans = _glfwPlatformStartDrag(window, thumbnail);
     if (ans != 0) _glfwFreeDragSourceData();
     return ans;

glfw/internal.h

@@ -668,6 +668,7 @@ struct _GLFWlibrary
     struct {
         GLFWDragSourceItem *items; size_t item_count;
         GLFWid window_id, instance_id; int operations;
+        bool needs_toplevel_on_wayland;
     } drag;
 };
 

glfw/wl_init.c

@@ -789,7 +789,7 @@ get_compositor_missing_capabilities(void) {
     C(single_pixel_buffer, wp_single_pixel_buffer_manager_v1); C(preferred_scale, has_preferred_buffer_scale);
     C(idle_inhibit, idle_inhibit_manager); C(icon, xdg_toplevel_icon_manager_v1); C(bell, xdg_system_bell_v1);
     C(window-tag, xdg_toplevel_tag_manager_v1); C(keyboard_shortcuts_inhibit, keyboard_shortcuts_inhibit_manager);
-    C(key-repeat, has_key_repeat_events);
+    C(key-repeat, has_key_repeat_events); C(top_level_drag, xdg_toplevel_drag_manager_v1);
 #define P(x) p += snprintf(p, sizeof(buf) - (p - buf), "%s ", x);
     if (_glfw.wl.xdg_wm_base_version < 6) P("window-state-suspended");
     if (_glfw.wl.xdg_wm_base_version < 5) P("window-capabilities");

glfw/wl_window.c

@@ -3325,8 +3325,8 @@ drag_source_cancelled(void *data UNUSED, struct wl_data_source *source UNUSED) {
     // Uber competent Wayland people contravene their own spec and make it
     // impossible to distinguish between drag cancelled and dropped but not
     // accepted. https://gitlab.freedesktop.org/wayland/wayland/-/issues/140
-    // so we assume this is a drop. Sigh.
-    cancel_drag(GLFW_DRAG_DROPPED);
+    // so we assume this is a drop unless we are in top-level mode. Sigh.
+    cancel_drag(_glfw.wl.drag.toplevel_xdg_toplevel ? GLFW_DRAG_CANCELLED : GLFW_DRAG_DROPPED);
 }
 
 
@@ -3411,7 +3411,7 @@ _glfwPlatformStartDrag(_GLFWwindow* window, const GLFWimage* thumbnail) {
             wl_surface_set_buffer_scale(_glfw.wl.drag.drag_icon, scale);
         }
 
-        if (_glfw.wl.xdg_toplevel_drag_manager_v1) {
+        if (_glfw.drag.needs_toplevel_on_wayland && _glfw.wl.xdg_toplevel_drag_manager_v1) {
             _glfw.wl.drag.toplevel_drag = xdg_toplevel_drag_manager_v1_get_xdg_toplevel_drag(
                 _glfw.wl.xdg_toplevel_drag_manager_v1, _glfw.wl.drag.source);
             if (!_glfw.wl.drag.toplevel_drag) return ENOMEM;

kitty/boss.py

@@ -1945,14 +1945,20 @@ def on_drop(self, os_window_id: int, drop: dict[str, bytes] | int, from_self: bo
                 w.on_drop(drop)
 
     def on_drag_source_finished(
-        self, was_dropped: bool, was_canceled: bool, accepted_mime_type: str, action: int, data: dict[str, bytes] | None
+        self, was_dropped: bool, was_canceled: bool, accepted_mime_type: str, action: int, data: dict[str, bytes] | None,
+        needs_toplevel_on_wayland: bool
     ) -> None:
         if (tab_id := int((data or {}).get(f'application/net.kovidgoyal.kitty-tab-{os.getpid()}', b'0').decode())
-        ) and get_tab_being_dragged()[0] == tab_id:
+        ) and get_tab_being_dragged()[0] == tab_id and (tab := self.tab_for_id(tab_id)):
+            if needs_toplevel_on_wayland:
+                for tm in self.all_tab_managers:
+                    if tm.tab_being_dropped:
+                        tm.on_tab_drop(0, 0, bypass_move=True)
+                        return
             set_tab_being_dragged()
             for tm in self.all_tab_managers:
                 tm.on_tab_drop_move()
-            if was_dropped and (tab := self.tab_for_id(tab_id)):  # detach tab into new OS Window
+            if was_dropped:  # detach tab into new OS Window
                 self._move_tab_to(tab)
 
     @ac('win', '''

kitty/glfw-wrapper.h

@@ -2302,7 +2302,7 @@ typedef GLFWdragsourcefun (*glfwSetDragSourceCallback_func)(GLFWwindow*, GLFWdra
 GFW_EXTERN glfwSetDragSourceCallback_func glfwSetDragSourceCallback_impl;
 #define glfwSetDragSourceCallback glfwSetDragSourceCallback_impl
 
-typedef int (*glfwStartDrag_func)(GLFWwindow*, const GLFWDragSourceItem*, size_t, const GLFWimage*, int);
+typedef int (*glfwStartDrag_func)(GLFWwindow*, const GLFWDragSourceItem*, size_t, const GLFWimage*, int, bool);
 GFW_EXTERN glfwStartDrag_func glfwStartDrag_impl;
 #define glfwStartDrag glfwStartDrag_impl
 

kitty/glfw.c

@@ -645,11 +645,13 @@ window_focus_callback(GLFWwindow *w, int focused) {
 #undef osw
 }
 
+#define TAB_DRAG_MIME_NUMBER 400
+
 static int
 is_droppable_mime(const char *mime) {
     static char tab_mime[64] = {0};
     if (!tab_mime[0]) snprintf(tab_mime, sizeof(tab_mime), "application/net.kovidgoyal.kitty-tab-%d", getpid());
-    if (strcmp(mime, tab_mime) == 0) return 4;
+    if (strcmp(mime, tab_mime) == 0) return TAB_DRAG_MIME_NUMBER;
     if (strcmp(mime, "text/uri-list") == 0) return 3;
     if (strcmp(mime, "text/plain;charset=utf-8") == 0) return 2;
     if (strcmp(mime, "text/plain") == 0) return 1;
@@ -794,10 +796,10 @@ free_drag_source(void) {
 static void
 drag_source_callback(GLFWwindow *window UNUSED, GLFWDragEvent *ev) {
 #define finish \
-    call_boss(on_drag_source_finished, "OOsiO", \
+    call_boss(on_drag_source_finished, "OOsiOO", \
             ds.was_dropped ? Py_True : Py_False, ds.was_canceled ? Py_True: Py_False, \
             ds.accepted_mime_type ? ds.accepted_mime_type : "", \
-            ds.action, ds.drag_data ? ds.drag_data : Py_None); \
+            ds.action, ds.drag_data ? ds.drag_data : Py_None, ds.needs_toplevel_on_wayland ? Py_True : Py_False); \
     free_drag_source();
 
     switch (ev->type) {
@@ -816,7 +818,9 @@ drag_source_callback(GLFWwindow *window UNUSED, GLFWDragEvent *ev) {
             ds.action = ev->action; break;
         case GLFW_DRAG_DROPPED:
             ds.was_dropped = true;
-            if (ev->action == GLFW_DRAG_OPERATION_NONE) { finish }
+            if (ev->action == GLFW_DRAG_OPERATION_NONE) {
+                finish
+            }
             break;
         case GLFW_DRAG_CANCELLED:
             ds.was_canceled = true;
@@ -2812,7 +2816,7 @@ change_drag_thumbnail(PyObject *self UNUSED, PyObject *args) {
         if (!get_thumbnail(global_state.drag_source.thumbnails, &thumbnail, idx)) return NULL;
         global_state.drag_source.thumbnail_idx = idx;
     } else global_state.drag_source.thumbnail_idx = -1;
-    errno = glfwStartDrag(w->handle, NULL, 0, thumbnail.pixels ? &thumbnail : NULL, -2);
+    errno = glfwStartDrag(w->handle, NULL, 0, thumbnail.pixels ? &thumbnail : NULL, -2, false);
     if (errno != 0) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;
@@ -2836,19 +2840,23 @@ start_drag_with_data(PyObject *self UNUSED, PyObject *args, PyObject *kw) {
     RAII_ALLOC(GLFWDragSourceItem, items, calloc(PyDict_Size(data_map), sizeof(GLFWDragSourceItem)));
     if (!items) { PyErr_NoMemory(); return NULL; }
     PyObject *key, *value; Py_ssize_t pos = 0; size_t num = 0;
+    bool needs_toplevel_on_wayland = false;
     while (PyDict_Next(data_map, &pos, &key, &value)) {
         if (!PyUnicode_Check(key)) { PyErr_SetString(PyExc_TypeError, "data_map must have string keys"); return NULL; }
         if (!PyBytes_Check(value)) { PyErr_SetString(PyExc_TypeError, "data_map must have bytes values"); return NULL; }
         GLFWDragSourceItem *item = items + num++;
         item->mime_type = PyUnicode_AsUTF8(key);
         item->optional_data = PyBytes_AS_STRING(value); item->data_size = PyBytes_GET_SIZE(value);
+        if (global_state.is_wayland && is_droppable_mime(item->mime_type) == TAB_DRAG_MIME_NUMBER)
+            needs_toplevel_on_wayland = true;
     }
     free_drag_source();
     global_state.drag_source.is_active = true;
+    global_state.drag_source.needs_toplevel_on_wayland = needs_toplevel_on_wayland;
     global_state.drag_source.drag_data = Py_NewRef(data_map);
     if (thumbnails) global_state.drag_source.thumbnails = Py_NewRef(thumbnails);
     global_state.drag_source.thumbnail_idx = thumbnail.pixels ? 0 : -1;
-    errno = glfwStartDrag(w->handle, items, num, thumbnail.pixels ? &thumbnail : NULL, operations);
+    errno = glfwStartDrag(w->handle, items, num, thumbnail.pixels ? &thumbnail : NULL, operations, needs_toplevel_on_wayland);
     if (errno != 0) {
         PyErr_SetFromErrno(PyExc_OSError);
         return NULL;

kitty/options/definition.py

@@ -1698,17 +1698,23 @@
 color is chosen to match the background color of the neighboring tab.
 ''')
 
-opt('tab_bar_drag_threshold', '5', option_type='positive_int',
-    long_text='''
+opt(
+    'tab_bar_drag_threshold',
+    '5',
+    option_type='positive_int',
+    long_text="""
 Control when dragging of tabs to re-order them happens.
 The value is the drag threshold in pixels, the distance the mouse must move
 before a drag begins. A value of zero disables tab dragging entirely.
 Dragging a tab to another kitty window moves it there, while dragging
-outside any kitty window detaches it into a new OS window. Note that on
-Wayland, :link:`because of poor design
-<https://gitlab.freedesktop.org/wayland/wayland/-/issues/140>` drag and cancel
-will still detach tabs.
-''')
+outside any kitty window detaches it into a new OS window.
+
+Note that on Wayland, :link:`because of poor design
+<https://gitlab.freedesktop.org/wayland/wayland/-/issues/140>` cancelling
+a drag will detach the tab. This is worked around for compositors that support
+:link:`xdg-toplevel-drag <https://wayland.app/protocols/xdg-toplevel-drag-v1>`.
+""",
+)
 egr()  # }}}
 
 

kitty/state.h

@@ -384,7 +384,7 @@ typedef struct GlobalState {
     } drop_dest;
 
     struct {
-        bool is_active, was_dropped, was_canceled;
+        bool is_active, was_dropped, was_canceled, needs_toplevel_on_wayland;
         char *accepted_mime_type;
         int action, thumbnail_idx;
         PyObject *drag_data, *thumbnails;

kitty/tabs.py

@@ -1608,14 +1608,16 @@ def on_tab_drop_move(self, tab_id: int = 0, is_dest: bool = False, x: int = 0, y
             self.layout_tab_bar()
 
     @update_tab_bar_visibility
-    def on_tab_drop(self, x: int, y: int) -> None:
+    def on_tab_drop(self, x: int, y: int, bypass_move: bool = False) -> None:
         if (td := self.tab_being_dropped) is None:
             return
         if (tab := get_boss().tab_for_id(td.data.tab_id)) is None:
             return
-        self.on_tab_drop_move(td.data.tab_id, True, x, y)
+        if not bypass_move:
+            self.on_tab_drop_move(td.data.tab_id, True, x, y)
         if (td := self.tab_being_dropped) is None:
             return
+        print(3333333333)
         self.tab_being_dropped = None
         atid = self.active_tab.id if self.active_tab else 0
         set_tab_being_dragged()