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2022-01-27-opencv-and-gtk.md (1072B)

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