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2022-01-27-opencv-and-gtk.md (1082B)

      1 title: Finding mouse location in Python + GTK + OpenCV.
      2 date: 2022-01-27 00:00
      3 ---
      4 
      5 Expanding on the tutorial:
      6 
      7 <https://nofurtherquestions.wordpress.com/2017/03/03/python-3-5-gtk-3-glade-and-opencv/>
      8 
      9 it originally had shown the following structure:
     10 
     11 ```
     12 - window1 (GtkWindow)
     13     - box1 (GtkBox)
     14         - grayscaleButton (GtkToggleButton)
     15         - image (GtkImage)
     16 ```
     17 
     18 According to <https://stackoverflow.com/a/24388310/189995> `GtkImage` does not
     19 generate events, so if you want to find the mouse location, put your
     20 `GtkImage` inside a `GtkEventBox`:
     21 
     22 ```
     23 - window1 (GtkWindow)
     24     - box1 (GtkBox)
     25         - grayscaleButton (GtkToggleButton)
     26         - eventbox (GtkEventBox)
     27             - image (GtkImage)
     28 ```
     29 
     30 and in `eventbox` set the `Common -> Events -> Pointer Motion` so you can add
     31 a handler to the `motion-notify-event` event.
     32 
     33 Now you can write your handler:
     34 
     35 ```python
     36 class Handler:
     37     …
     38     …
     39     …
     40     def onMotionNotifyEvent(*args):
     41         global current_mouse_location
     42     
     43         event = args[1]
     44 
     45         current_mouse_location = event.x, event.y
     46 ```