Скачать или смотреть How to Highlight Replaced Letters in Tkinter Text Widgets

Learn how to effectively manage highlights in Tkinter by detecting deleted letters in a text input and highlighting only the newly typed ones.
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This video is based on the question https://stackoverflow.com/q/63557691/ asked by the user 'ghazigamer' ( https://stackoverflow.com/u/11140389/ ) and on the answer https://stackoverflow.com/a/63559551/ provided by the user 'j_4321' ( https://stackoverflow.com/u/6415268/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering Text Highlighting in Tkinter: Detecting Deletions

When working with graphical user interfaces in Python using Tkinter, you may encounter various challenges, especially when dealing with dynamic text input. One common issue is ensuring that highlights in a text area update accurately when the user modifies their input. In this guide, we'll tackle a specific problem: how to check if a letter or word is deleted from an entry field and only highlight the newly entered letter or word.

The Problem

Imagine you have a simple Tkinter application where users can enter a string in one text field and type a search term in another. Your goal is to highlight the occurrences of the search term in the string field. The issue arises when the user deletes a letter from the search term. If the search term changes from "g" to "h", both letters might remain highlighted due to the previous search operation, leading to confusion. The requirement is to update the highlight to reflect only the new input accurately.

Understanding the Existing Code

Here’s a simplified version of the function responsible for handling the highlight:

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

In this code:

The search method is called to find the string in the text widget.

If the string is found, a "match" tag configuration is applied to highlight it.

However, there's no mechanism to remove the highlight of previous characters that are no longer part of the search string.

The Solution

To ensure only the newly typed letters are highlighted, we need to make a few adjustments to the Find() method. Here’s a step-by-step guide to improve the function:

Step 1: Clear Previous Highlights

Start by removing any previous highlights before searching:

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

Step 2: Check for Empty Input

Before proceeding with the search operation, add a check to see if the entry field is empty:

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

Step 3: Configure Tag Only Once

Instead of reconfiguring the “match” tag each time the Find() method is called, do it once during widget initialization:

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

Step 4: Bind Events Once

Similarly, the event binding should only be set once:

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

Full Example Code

Here is the complete revised example code that integrates all these improvements:

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

Conclusion

By implementing these straightforward changes, you can create a responsive Tkinter application that accurately highlights only the letters currently in the entry field. This not only enhances the user experience but also prevents confusion when modifying search terms. So, the next time you build a Tkinter app, keep this highlighting technique in mind to improve its functionality!