Implement sending drag start message to client

docs/dnd-protocol.rst

@@ -257,7 +257,7 @@ image by sending::
 
 Where ``idx`` is now a zero based index with zero being the first image and so on.
 
-Once the terminal program has present all data and images for the drag
+Once the terminal program has sent all data and images for the drag
 operation, it indicates the drag should be started by sending ``t=P:x=-1``. At
 this time if the user has already cancelled the drag or the terminal determines
 the drag operation is not allowed, it must respond with ``t=R ; EPERM``. If any

kitty/dnd.c

@@ -854,3 +854,8 @@ drop_left_child(Window *w) {
         queue_payload_to_child(w->id, w->drop.client_id, &w->drop.pending, buf, header_size, NULL, 0, false);
     }
 }
+
+void
+drag_free_offer(Window *w) {
+    (void)w;
+}

kitty/dnd.h

@@ -21,3 +21,6 @@ size_t drop_update_mimes(Window *w, const char **allowed_mimes, size_t allowed_m
 void drop_dispatch_data(Window *w, const char *mime_type, const char *data, ssize_t sz);
 void drop_finish(Window *w);
 void dnd_set_test_write_func(PyObject *func);
+
+
+void drag_free_offer(Window *w);

kitty/glfw.c

@@ -1056,6 +1056,12 @@ free_drag_source(void) {
     zero_at_ptr(&ds);
 }
 
+void
+cancel_current_drag_source(void) {
+    if (!ds.from_os_window) return; OSWindow *w = os_window_for_id(ds.from_os_window); if (!w || !w->handle) return;
+    glfwStartDrag(w->handle, NULL, 0, NULL, -3, false);
+}
+
 static void
 drag_source_callback(GLFWwindow *window UNUSED, GLFWDragEvent *ev) {
 #define finish \
@@ -3115,6 +3121,8 @@ 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;
+    global_state.drag_source.from_os_window = w->id;
+    global_state.drag_source.from_window = 0;
     errno = glfwStartDrag(w->handle, NULL, 0, thumbnail.pixels ? &thumbnail : NULL, -2, false);
     if (errno != 0) {
         PyErr_SetFromErrno(PyExc_OSError);

kitty/mouse.c

@@ -643,6 +643,10 @@ handle_scrollbar_mouse(Window *w, int button, MouseAction action, int modifiers
 }
 // }}}
 
+static double
+distance(double x1, double y1, double x2, double y2) {
+    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
+}
 
 HANDLER(handle_move_event) {
     modifiers &= ~GLFW_LOCK_MASK;
@@ -672,11 +676,13 @@ HANDLER(handle_move_event) {
         int sz = encode_mouse_button(w, button, button >=0 ? DRAG : MOVE, modifiers);
         if (sz > 0) { mouse_event_buf[sz] = 0; write_escape_code_to_child(screen, ESC_CSI, mouse_event_buf); }
     }
-}
-
-static double
-distance(double x1, double y1, double x2, double y2) {
-    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
+    if (w->drag_source.can_offer && w->drag_source.initial_left_press.at && distance(w->mouse_pos.global_x, w->mouse_pos.global_y, w->drag_source.initial_left_press.x, w->drag_source.initial_left_press.y) > OPT(drag_threshold)) {
+        zero_at_ptr(&w->drag_source.initial_left_press);
+        snprintf(mouse_event_buf, sizeof(mouse_event_buf), "%d;t=o:x=%d:y=%d:X=%d:Y=%d",
+            DND_CODE, w->mouse_pos.cell_x, w->mouse_pos.cell_y, (int)w->mouse_pos.global_x, (int)w->mouse_pos.global_y);
+        write_escape_code_to_child(screen, ESC_OSC, mouse_event_buf);
+        debug("Sent drag start event to child\n");
+    }
 }
 
 static void
@@ -870,6 +876,15 @@ HANDLER(handle_button_event) {
 
     bool a, b;
     if (!set_mouse_position(w, &a, &b)) return;
+    if (button == GLFW_MOUSE_BUTTON_LEFT) {
+        if (is_release) {
+            zero_at_ptr(&w->drag_source.initial_left_press);
+        } else if (w->drag_source.can_offer) {
+            w->drag_source.initial_left_press.x = w->mouse_pos.global_x;
+            w->drag_source.initial_left_press.y = w->mouse_pos.global_x;
+            w->drag_source.initial_left_press.at = monotonic();
+        }
+    }
     id_type wid = w->id;
     if (!dispatch_mouse_event(w, button, is_release ? -1 : 1, modifiers, screen->modes.mouse_tracking_mode != 0)) {
         if (!suppress_child_forwarding && screen->modes.mouse_tracking_mode != 0) {

kitty/options/definition.py

@@ -884,7 +884,7 @@
 '''
     )
 
-opt('drag_threshold', '5', option_type='positive_int', long_text='''
+opt('drag_threshold', '5', option_type='positive_int', ctype='int', long_text='''
 The threshold distance the mouse must move to start a drag and drop. Dragging
 works for tabs and windows. You can drag tabs to re-order them, detach
 them into new OS Windows or move them to another OS Window. Similarly,

kitty/screen.c

@@ -1530,16 +1530,23 @@ screen_handle_dnd_command(Screen *self, const DnDCommand *cmd, const uint8_t *pa
             }
         } break;
         case 's': {
-            if (cmd->payload_sz)
-                drop_request_uri_data(w, (const char*)payload, cmd->payload_sz);
-            else
-                drop_send_einval(w);
+            if (cmd->payload_sz) drop_request_uri_data(w, (const char*)payload, cmd->payload_sz);
+            else drop_send_einval(w);
         } break;
         case 'd': {
-            if (cmd->cell_x > 0)
-                drop_handle_dir_request(w, (uint32_t)cmd->cell_x, cmd->cell_y);
-            else
-                drop_send_einval(w);
+            if (cmd->cell_x > 0) drop_handle_dir_request(w, (uint32_t)cmd->cell_x, cmd->cell_y);
+            else drop_send_einval(w);
+        } break;
+        case 'o': {
+            if (cmd->payload_sz > 0) ;
+            else w->drag_source.can_offer = true;
+        } break;
+        case 'O': {
+            drag_free_offer(w);
+            w->drag_source.can_offer = false;
+            if (global_state.drag_source.is_active && global_state.drag_source.from_window == w->id) {
+                cancel_current_drag_source();
+            }
         } break;
     }
 }

kitty/state.h

@@ -153,6 +153,7 @@ typedef struct Options {
     double momentum_scroll;
     double window_drag_tolerance;
     bool generate_256_palette;
+    int drag_threshold;
 } Options;
 
 typedef struct WindowLogoRenderData {
@@ -284,6 +285,10 @@ typedef struct Window {
         monotonic_t last_file_send_at;  /* time of last successful file chunk write */
         id_type file_send_timer;        /* pending file-send retry timer, 0 = none */
     } drop;
+    struct {
+        bool can_offer;
+        struct { double x, y; monotonic_t at; } initial_left_press;
+    } drag_source;
 } Window;
 
 typedef struct BorderRect {
@@ -441,6 +446,7 @@ typedef struct GlobalState {
 
     struct {
         bool is_active, was_dropped, was_canceled, needs_toplevel_on_wayland;
+        id_type from_window, from_os_window;
         char *accepted_mime_type;
         int action, thumbnail_idx;
         PyObject *drag_data, *thumbnails;
@@ -571,3 +577,4 @@ bool current_framebuffer_is_ok(void);
 void request_drop_status_update(OSWindow *osw);
 void register_mimes_for_drop(OSWindow *w, const char **mimes, size_t sz);
 void request_drop_data(OSWindow *w, id_type wid, const char* mime);
+void cancel_current_drag_source(void);