Скачать или смотреть Understanding PyQt5 Animation Issues: A Guide to Fixing Animation Not Occurring When Appended

Discover how to resolve the issue of animations not manifesting in your PyQt5 application. Learn the difference between animation scoping and object ownership.
---
This video is based on the question https://stackoverflow.com/q/65559142/ asked by the user 'Ecto Ruseff' ( https://stackoverflow.com/u/14387519/ ) and on the answer https://stackoverflow.com/a/65559373/ provided by the user 'eyllanesc' ( https://stackoverflow.com/u/6622587/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Animations not occurring when animation objects are appended to the list

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding PyQt5 Animation Issues: A Guide to Fixing Animation Not Occurring When Appended

Animations can bring your applications to life, providing an engaging user experience. However, when working with PyQt5, you might face issues, such as animations not occurring when appending animation objects to a list. In this guide, we will delve into why this issue occurs and how you can solve it effectively.

The Problem: Why Aren't My Animations Working?

You have created an interface with two frames and a button in your PyQt application, intending to animate the resizing of the frames when the button is clicked. While your first approach works perfectly, an alternative method you've devised fails to animate the frames. This situation can be frustrating, especially when trying to simplify your code with a more dynamic approach.

What Causes the Issue?

The root of the problem lies in the scope and lifetime of the animations being created in your second function. When you store animations in a list that is immediately discarded after the function execution, the animations also get disposed of, resulting in no visible effects. Let’s explore the solution to this issue.

The Solution: Managing Animation Lifetimes

To ensure your animations function as expected, you need to extend their lifetimes. There are several strategies to achieve this:

1. Making the Animation List an Attribute of the Class

One straightforward fix is to create a class attribute for your animations, ensuring they remain in scope for their duration. However, the more effective solution involves managing their parent-child relationship using QObject.

2. Using Object Parentage for Animations

The animations are instances of QPropertyAnimation, which is derived from QObject. By passing the respective frames as parents when creating the animations, you ensure they persist even when the local variable is out of scope. Here’s how you can implement this change:

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

Explanation of the Code

Parenting: By setting parent=item, you ensure each animation's lifecycle is tied to their corresponding frame. This means that even after the function ends, the animations will remain active.

Alternating Values: The setEndValue method is conditionally toggling the dimensions based on the self.thing boolean.

Enhanced Performance with Animation Groups

If you plan to execute several animations simultaneously, consider using the QParallelAnimationGroup. This can help optimize performance and provide a cleaner implementation. Here's how you can modify your function using an animation group:

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

Why Use QParallelAnimationGroup?

Smooth Execution: It allows multiple animations to be started, managed, and synchronized together, leading to a smoother animation experience.

Less Code Redundancy: It keeps your code concise and manageable, especially useful in applications requiring numerous animations.

Conclusion

Understanding how to manage objects and their lifetimes in PyQt5 is crucial for creating effective animations. By recognizing the importance of proper object parenting and utilizing animation groups, you can create smooth and engaging animations in your applications without weak references causing undesired behaviors. Armed with these techniques, you should be able to animate frames dynamically without any hiccups.

Happy coding!