1 files changed, 152 insertions, 1 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 3cc730c4eeb..557555e7a4d 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -1104,6 +1104,13 @@ struct frame *x_dnd_finish_frame;
    important information.  */
 bool x_dnd_waiting_for_finish;
 
+/* Whether or not to move the tooltip along with the mouse pointer
+   during drag-and-drop.  */
+static bool x_dnd_update_tooltip;
+
+/* Monitor attribute list used for updating the tooltip position.  */
+static Lisp_Object x_dnd_monitors;
+
 /* The display the drop target that is supposed to send information is
    on.  */
 static Display *x_dnd_finish_display;
@@ -4190,6 +4197,12 @@ x_free_dnd_targets (void)
 }
 
 static void
+x_clear_dnd_monitors (void)
+{
+  x_dnd_monitors = Qnil;
+}
+
+static void
 x_free_dnd_toplevels (void)
 {
   if (!x_dnd_use_toplevels || !x_dnd_toplevels)
@@ -10738,7 +10751,8 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time time, Atom xaction,
                            Lisp_Object return_frame, Atom *ask_action_list,
                            const char **ask_action_names, size_t n_ask_actions,
                            bool allow_current_frame, Atom *target_atoms,
-                           int ntargets, Lisp_Object selection_target_list)
+                           int ntargets, Lisp_Object selection_target_list,
+                           bool follow_tooltip)
 {
 #ifndef USE_GTK
   XEvent next_event;
@@ -10941,6 +10955,15 @@ x_dnd_begin_drag_and_drop (struct frame *f, Time time, Atom xaction,
       unblock_input ();
     }
 
+  if (follow_tooltip)
+    {
+      x_dnd_monitors
+        = Fx_display_monitor_attributes_list (frame);
+      record_unwind_protect_void (x_clear_dnd_monitors);
+    }
+
+  x_dnd_update_tooltip = follow_tooltip;
+
   /* This shouldn't happen.  */
   if (x_dnd_toplevels)
     x_dnd_free_toplevels (true);
@@ -15131,6 +15154,106 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
     }
 }
 
+static void
+x_dnd_compute_tip_xy (int *root_x, int *root_y, Lisp_Object attributes)
+{
+  Lisp_Object monitor, geometry;
+  int min_x, min_y, max_x, max_y;
+  int width, height;
+
+  width = FRAME_PIXEL_WIDTH (XFRAME (tip_frame));
+  height = FRAME_PIXEL_HEIGHT (XFRAME (tip_frame));
+
+  max_y = -1;
+
+  /* Try to determine the monitor where the mouse pointer is and
+     its geometry.  See bug#22549.  */
+  while (CONSP (attributes))
+    {
+      monitor = XCAR (attributes);
+      geometry = assq_no_quit (Qgeometry, monitor);
+
+      if (CONSP (geometry))
+        {
+          min_x = XFIXNUM (Fnth (make_fixnum (1), geometry));
+          min_y = XFIXNUM (Fnth (make_fixnum (2), geometry));
+          max_x = min_x + XFIXNUM (Fnth (make_fixnum (3), geometry));
+          max_y = min_y + XFIXNUM (Fnth (make_fixnum (4), geometry));
+
+          if (min_x <= *root_x && *root_x < max_x
+              && min_y <= *root_y && *root_y < max_y)
+            break;
+
+          max_y = -1;
+        }
+
+      attributes = XCDR (attributes);
+    }
+
+  /* It was not possible to determine the monitor's geometry, so we
+     assign some sane defaults here: */
+  if (max_y < 0)
+    {
+      min_x = 0;
+      min_y = 0;
+      max_x = x_display_pixel_width (FRAME_DISPLAY_INFO (x_dnd_frame));
+      max_y = x_display_pixel_height (FRAME_DISPLAY_INFO (x_dnd_frame));
+    }
+
+  if (*root_y + XFIXNUM (tip_dy) <= min_y)
+    *root_y = min_y; /* Can happen for negative dy */
+  else if (*root_y + XFIXNUM (tip_dy) + height <= max_y)
+    /* It fits below the pointer */
+    *root_y += XFIXNUM (tip_dy);
+  else if (height + XFIXNUM (tip_dy) + min_y <= *root_y)
+    /* It fits above the pointer.  */
+    *root_y -= height + XFIXNUM (tip_dy);
+  else
+    /* Put it on the top.  */
+    *root_y = min_y;
+
+  if (*root_x + XFIXNUM (tip_dx) <= min_x)
+    *root_x = 0; /* Can happen for negative dx */
+  else if (*root_x + XFIXNUM (tip_dx) + width <= max_x)
+    /* It fits to the right of the pointer.  */
+    *root_x += XFIXNUM (tip_dx);
+  else if (width + XFIXNUM (tip_dx) + min_x <= *root_x)
+    /* It fits to the left of the pointer.  */
+    *root_x -= width + XFIXNUM (tip_dx);
+  else
+    /* Put it left justified on the screen -- it ought to fit that way.  */
+    *root_x = min_x;
+}
+
+static void
+x_dnd_update_tooltip_position (int root_x, int root_y)
+{
+  struct frame *tip_f;
+
+  if (!x_dnd_in_progress || !x_dnd_update_tooltip)
+    return;
+
+  if (!FRAMEP (tip_frame))
+    return;
+
+  tip_f = XFRAME (tip_frame);
+
+  if (!FRAME_LIVE_P (tip_f)
+      || (FRAME_X_DISPLAY (tip_f)
+          != FRAME_X_DISPLAY (x_dnd_frame)))
+    return;
+
+  if (tip_window != None
+      && FIXNUMP (tip_dx) && FIXNUMP (tip_dy))
+    {
+      x_dnd_compute_tip_xy (&root_x, &root_y,
+                            x_dnd_monitors);
+
+      XMoveWindow (FRAME_X_DISPLAY (x_dnd_frame),
+                   tip_window, root_x, root_y);
+    }
+}
+
 /* Get the window underneath the pointer, see if it moved, and update
    the DND state accordingly.  */
 static void
@@ -15292,6 +15415,8 @@ x_dnd_update_state (struct x_display_info *dpyinfo, Time timestamp)
             xm_send_drag_motion_message (dpyinfo, FRAME_X_WINDOW (x_dnd_frame),
                                          target, &dmsg);
         }
+
+      x_dnd_update_tooltip_position (root_x, root_y);
     }
   /* The pointer moved out of the screen.  */
   else if (x_dnd_last_protocol_version != -1)
@@ -17462,6 +17587,9 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                                                target, &dmsg);
               }
 
+            x_dnd_update_tooltip_position (event->xmotion.x_root,
+                                           event->xmotion.y_root);
+
             goto OTHER;
           }
 
@@ -17966,6 +18094,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                   {
                     x_dnd_end_window = x_dnd_last_seen_window;
                     x_dnd_in_progress = false;
+
+                    if (x_dnd_update_tooltip
+                        && FRAMEP (tip_frame)
+                        && FRAME_LIVE_P (XFRAME (tip_frame))
+                        && (FRAME_X_DISPLAY (XFRAME (tip_frame))
+                            == FRAME_X_DISPLAY (x_dnd_frame)))
+                      Fx_hide_tip ();
+
                     x_dnd_finish_frame = x_dnd_frame;
 
                     if (x_dnd_last_seen_window != None
@@ -19172,6 +19308,8 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                                                      target, &dmsg);
                     }
 
+                  x_dnd_update_tooltip_position (xev->root_x, xev->root_y);
+
                   goto XI_OTHER;
                 }
 
@@ -19332,6 +19470,16 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                           x_dnd_end_window = x_dnd_last_seen_window;
                           x_dnd_in_progress = false;
 
+                          /* If a tooltip that we're following is
+                             displayed, hide it now.  */
+
+                          if (x_dnd_update_tooltip
+                              && FRAMEP (tip_frame)
+                              && FRAME_LIVE_P (XFRAME (tip_frame))
+                              && (FRAME_X_DISPLAY (XFRAME (tip_frame))
+                                  == FRAME_X_DISPLAY (x_dnd_frame)))
+                            Fx_hide_tip ();
+
                           /* This doesn't have to be marked since it
                              is only accessed if
                              x_dnd_waiting_for_finish is true, which
@@ -26645,6 +26793,9 @@ syms_of_xterm (void)
   x_error_message = NULL;
   PDUMPER_IGNORE (x_error_message);
 
+  x_dnd_monitors = Qnil;
+  staticpro (&x_dnd_monitors);
+
   DEFSYM (Qvendor_specific_keysyms, "vendor-specific-keysyms");
   DEFSYM (Qlatin_1, "latin-1");
   DEFSYM (Qnow, "now");