Enhance Your Flutter App: Change Text Color Dynamically Using Indices in Flutter

Discover how to dynamically change the color of parts of text based on index intervals in `Flutter`, perfect for your next app project.
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Change Text Color Dynamically in Flutter

When building applications with Flutter, you might come across scenarios where you want to draw attention to specific parts of the text. A common request is to change the color of a substring dynamically at timed intervals. In this post, we will walk through how to achieve this effect using Flutter’s powerful widget system.

Understanding the Problem

Suppose you have a string with multiple words, such as "achievement admission advertise pencil". Additionally, assume you have a list of index pairs indicating which parts of the word should be highlighted in color. For example, you want to highlight the characters from index 3 to 5, then change the highlight to a different range after a specific duration.

Example Requirements:

Change the text color of specific indices to green.

Allow changes to occur every 2 seconds, moving from one set of indices to another.

After all indices are processed, revert the text back to its original color.

The Solution: Creating a Custom Widget

To accomplish this functionality in your Flutter app, we can create a custom widget called SyllableText. This widget will manage the text color changes for specified index ranges over time.

Step-by-Step Implementation

1. Create the Pair Class

This class will hold the start and end indices for the text ranges you want to highlight.

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

2. Build the SyllableText Widget

Now, we need to create the SyllableText widget which will take care of highlighting parts of the text.

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

Explanation of the Code

State Management: The widget is a stateful widget which maintains the currentPartIndex. This index determines which part of the text will be highlighted.

Text Rendering: The build method constructs the text widget. Depending on the current index, it calculates the start, colored, and end segments of the text and renders them accordingly.

Example Usage

To use the SyllableText in your Flutter app, the setup would look like this:

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

Conclusion

By implementing the SyllableText widget, you can create a dynamic and engaging user experience in your Flutter applications. Changing text color based on index intervals not only draws users' attention but also enhances the visual appeal of your app. Try incorporating this widget into your next Flutter project, and see how it transforms your text displays!