Hey Semih, I’ve run into this exact touch scrolling quirk with Tkinter before—let’s get it sorted out for you.

The root issue here is that Tkinter’s default mouse wheel bindings (<MouseWheel> on Windows) don’t automatically map to touchscreen swipe gestures. While your scrollbar works because it’s a native widget that handles touch input, the Canvas itself needs explicit code to recognize and respond to touch swipes.

Here’s how to implement touch scrolling for your Canvas: #

First, you’ll need to bind Tkinter’s touch-specific events to your Canvas, then track the swipe motion to adjust the scroll position.

1. Add variables to track touch state
   In your app’s initialization (or wherever you set up the Canvas), add a variable to store the starting y-coordinate of the touch:

   # Inside your class or main setup
   self.touch_start_y = None
   

2. Bind touch events to the Canvas
   Bind the three key touch events (<TouchPress>, <TouchRelease>, <TouchMotion>) to handler functions:

   # Replace 'self.canvas' with your actual Canvas instance
   self.canvas.bind('<TouchPress>', self.on_touch_press)
   self.canvas.bind('<TouchRelease>', self.on_touch_release)
   self.canvas.bind('<TouchMotion>', self.on_touch_motion)
   

3. Implement the touch handler functions
   These functions will track the swipe direction and adjust the Canvas scroll:

   def on_touch_press(self, event):
       # Record the starting y position when the screen is touched
       self.touch_start_y = event.y
   
   def on_touch_release(self, event):
       # Reset the starting position when the touch ends
       self.touch_start_y = None
   
   def on_touch_motion(self, event):
       if self.touch_start_y is not None:
           # Calculate how far the finger has swiped
           swipe_delta = self.touch_start_y - event.y
           # Adjust scroll speed by dividing delta (tweak the 10 value to your liking)
           scroll_amount = int(swipe_delta / 10)
           # Scroll the Canvas—use 'units' for smooth scrolling or 'pages' for larger jumps
           self.canvas.yview_scroll(scroll_amount, 'units')
           # Update the starting position for the next motion event (keeps scrolling smooth)
           self.touch_start_y = event.y
   

Quick Notes to Tweak the Behavior: #

• Scroll Direction: If the scroll is reversed (swiping up scrolls down), just flip the sign of swipe_delta (change to event.y - self.touch_start_y).
• Scroll Speed: The 10 in scroll_amount = int(swipe_delta / 10) controls how sensitive the scroll is. Lower numbers make scrolling faster, higher numbers make it slower—adjust based on your app’s needs.
• Confirm Scrollbar Binding: Double-check that your Canvas and Scrollbar are linked correctly (you probably already have this, but just to be sure):

  scrollbar = tk.Scrollbar(root, orient="vertical", command=self.canvas.yview)
  self.canvas.configure(yscrollcommand=scrollbar.set)
  

Once you add this code, swiping up or down on the Canvas area should behave just like using a mouse wheel on Windows.

内容的提问来源于stack exchange，提问作者Semih