Скачать или смотреть Fixing the Canvas Drawing Issue in Tkinter Pop-Up Windows

Discover simple solutions to ensure your Tkinter canvas displays drawings correctly when a Pop-Up window is opened!
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This video is based on the question https://stackoverflow.com/q/70916487/ asked by the user 'Daniel Casasampera' ( https://stackoverflow.com/u/11551227/ ) and on the answer https://stackoverflow.com/a/70917564/ provided by the user 'Aram SEMO' ( https://stackoverflow.com/u/15810641/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing the Canvas Drawing Issue in Tkinter Pop-Up Windows

When building applications with Tkinter, you might run into some issues regarding the visibility of your canvas elements, especially when using Pop-Up windows. If you've faced the problem where your canvas drawings don't appear until after selecting a tab in your Notebook, you're not alone! This guide will walk you through understanding the problem and provide a clear solution to make your drawings visible right when the Pop-Up window is created.

The Problem

You may have a Tkinter program where you implement a Pop-Up window intended for additional functionality. This window contains a Notebook widget with various tabs, each associated with its specific canvas drawing. However, the canvas drawings only appear once a tab is selected, leaving users wondering whether anything was meant to be displayed in the first place. This is not ideal for user experience.

To illustrate, the code snippet provided below demonstrates the issue:

[[See Video to Reveal this Text or Code Snippet]]

In the PopUpwindow, you set up a Notebook and attach frames that switch based on the active tab. The missing drawings issue seems to stem from how the canvas is initialized with dimensions that may not be accurately set until user interaction occurs.

The Solution

Understanding Why It Happens

The core issue lies in the handling of dimensions within the draw_frame1 and draw_frame2 methods. The canvas doesn't have the correct width and height available immediately upon the creation of the Pop-Up, meaning it won't render the drawings properly until the user clicks on a tab, updating its dimensions.

Refreshing the Canvas on Window Resize

To solve this problem, you need to bind the <Configure> event to the Notebook. This way, whenever the window is resized or opened, the canvas can refresh its drawings accordingly. Here's how to implement the solution effectively:

Bind the <Configure> event to the Notebook.

Invoke the drawing method whenever the notebook tab changes or the window is resized.

Here's the updated section of your code with the necessary binding added:

[[See Video to Reveal this Text or Code Snippet]]

Full Working Code

For your convenience, here is the complete example, now working correctly to display the canvas drawings when the Pop-Up window is opened:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you ensure that your canvas drawings appear immediately when the Pop-Up window is opened, regardless of the tab selection. This not only improves the usability of your Tkinter application but also contributes to a more polished user interface. Happy coding!