Does InvalidateVisual works in a lazy way?

c#, custom-controls, invalidation, rendering, wpf

Solution

The online help answers your question:

Online help for InvalidateVisual:

This method calls InvalidateArrange internally.

Online help for InvalidateArrange:

Invalidates the arrange state (layout) for the element. After the invalidation, the element will have its layout updated, which will occur asynchronously unless subsequently forced by UpdateLayout.

In other words: `InvalidateVisual` does not have an effect immediately; it waits until your current code has finished (unless you have calls to UpdateLayout).

You also can look at Microsoft's reference source: http://referencesource.microsoft.com/#q=UIElement.InvalidateArrange . You will see that `InvalidateArrange()` does not call any blocking code; it returns immediately.

Problem

Original source