From a1046a13da52e0b4ad4a552d27a535be2a604f5c Mon Sep 17 00:00:00 2001
From: likai <likai@kylinos.cn>
Date: Wed, 7 Aug 2024 22:01:15 +0800
Subject: [PATCH] gesture: set widget x and y if coordinate translation between
 widgets fails

Bug Description: In a GTK+ application with a menu bar, clicking the
menu item displays a dialog. However, when the user opens this dialog
and drags the parent window's menu bar with the cursor, the dialog
gets moved.
Issue: When _gtk_gesture_update_point calls the _update_widget_coordinates
function, the local variables x and y are not explicitly initialized, leading
to arbitrary values. For instance, in my case, x was 32767 and y was
-145750164 . These values are used in the subsequent call to
gtk_widget_translate_coordinates. In gtk_widget_translate_coordinates,
if ancestor is NULL, the function returns FALSE, and dest_x and dest_y
are not updated. The incorrect values of x and y cause data->widget_x
and data->widget_y to be incorrect, ultimately leading to abnormal
x and y values in the gtk_gesture_drag_update function.

To avoid this, we should set x and y to values clearly outside the widget.

Signed-off-by: Li Kai <likai@kylinos.cn>
---
 gtk/gtkgesture.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/gtk/gtkgesture.c b/gtk/gtkgesture.c
index 48cf9ba4de..bfc8ce08a5 100644
--- a/gtk/gtkgesture.c
+++ b/gtk/gtkgesture.c
@@ -125,6 +125,7 @@
 #include "gtkmain.h"
 #include "gtkintl.h"
 #include "gtkmarshalers.h"
+#include <math.h>
 
 typedef struct _GtkGesturePrivate GtkGesturePrivate;
 typedef struct _PointData PointData;
@@ -472,7 +473,7 @@ _update_widget_coordinates (GtkGesture *gesture,
   GtkWidget *event_widget, *widget;
   GtkAllocation allocation;
   gdouble event_x, event_y;
-  gint wx, wy, x, y;
+  gint x, y;
 
   event_widget = gtk_get_event_widget (data->event);
 
@@ -486,6 +487,7 @@ _update_widget_coordinates (GtkGesture *gesture,
 
   while (window && window != event_widget_window)
     {
+      gint wx, wy;
       gdk_window_get_position (window, &wx, &wy);
       event_x += wx;
       event_y += wy;
@@ -502,13 +504,20 @@ _update_widget_coordinates (GtkGesture *gesture,
       event_y -= allocation.y;
     }
 
-  gtk_widget_translate_coordinates (event_widget, widget,
-                                    event_x, event_y, &x, &y);
-  /* gtk_widget_translate() loses the fractional part so we need to
-   * add it back to not lose accuracy */
-  data->widget_x = x + (event_x - (int)event_x);
-  data->widget_y = y + (event_y - (int)event_y);
-
+  if (gtk_widget_translate_coordinates (event_widget, widget,
+                                        event_x, event_y, &x, &y))
+    {
+      /* gtk_widget_translate() loses the fractional part so we need to
+       * add it back to not lose accuracy */
+      data->widget_x = x + (event_x - (int)event_x);
+      data->widget_y = y + (event_y - (int)event_y);
+    }
+  else
+    {
+      /* Mark the coordinates well outside the widget, to
+       * signal that the translation has failed */
+      data->widget_x = data->widget_y = NAN;
+    }
 }
 
 static GtkEventSequenceState