Solving Keyboard Management in PyQt5: A Guide to Stopping Keystroke Tracking in Separate Threads

Learn how to effectively manage keystrokes in your `PyQt5` applications. This guide discusses using threads for keyboard tracking and how to correctly stop them, improving the functionality and responsiveness of your application.
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Solving Keyboard Management in PyQt5: A Guide to Stopping Keystroke Tracking in Separate Threads

In developing interactive applications with PyQt5, handling keyboard events is a common requirement, especially for applications that control hardware—like drones. However, one issue that many developers encounter is how to effectively start and stop keystroke tracking using separate threads, especially when dealing with libraries like keyboard. Let's walk through this problem together and provide a clear solution to properly manage keyboard events without unintended consequences.

The Problem

While working on a PyQt5 GUI that tracks keystrokes through a separate thread, the developer faced an issue where the keyboard tracking did not stop after pressing a button twice. Here is a simplified description of the scenario:

The program starts tracking keystrokes when a control button is pressed for the first time.

A second press of the button should stop tracking and reset the state.

However, in the original implementation, the keyboard kept listening for events, leading to unexpected behavior.

The initial code used threads to handle the keyboard tracking:

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

When the button was pressed again, the keyboard library continued to track keys, as the callback was still active. This is where we need a better approach.

The Solution

It turns out that managing the keyboard events does not necessarily require threading. Instead, we can use the keyboard library's own hooks and unhooks to control the start and stop of keystroke tracking. Here is how we resolved the problem:

Step 1: Refine the Keyboard Class

We simplified the keyboard management by creating a QKeyBoard class that directly handles the keystroke events:

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

Step 2: Update the UI to Manage State

In our UI class, we connect the button state to start and stop tracking:

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

Step 3: Running the Application

Finally, we set up our main method to run the application:

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

Conclusion

By refactoring the code to use hooks and unhooks instead of relying on threading, we can effectively manage keyboard event tracking in PyQt5. This ensures that when the button is pressed again, the keyboard stops tracking the keystrokes as expected.

By following the approach outlined in this post, you can improve the responsiveness and functionality of your PyQt5 applications, allowing for better user experience when controlling drones or other hardware devices.

Implement this in your own projects, and experience the difference in managing keyboard inputs!