Best practices for managing elements

This page describes the best practices for managing elements in the visual tree.

Pre-create hierarchies

It’s a slow operation to create elements and load them in a hierarchy. To avoid this you can pre-create the elements in a hierarchy, and use display:none to hide them and only display them when needed. However, it might consume more memory to create many elements at the same time.

Pool recurring elements

Elements pooling is to keep hold of elements that you might recreate them later on, rather than creating elements with new() every time and letting go of them.

It’s important to be fully in control of all elements that you pool and make sure you reset them properly before you return them to the pool. Otherwise, the pooling system can become unstable and troublesome. For example, it’s impossible to clean up an element if you pool elements while registering event callbacks or setting internal non-serialized state at the same time.

Keep the number of visible elements low

To keep the number of visual elements low, use ListView when possible. ListView pools elements and recycles elements as the user scrolls.

Alternatively, you can implement your own pool and recycle mechanism similar to the ListView, and use the following to manage the visible area:

• To observe the size of a container, use GeometryChangedEvent
• To compute the size of children, use the VisualElement.layout property

その他の参考資料

• The visual tree
• Introduction to visual elements and visual tree