Why TemplateContainer's size is always 0X0?

Hello! The template container should resize according to the elements inside of it. Is it possible that your elements inside the template are using absolute position? If that's not the case, could you share your uxml file and the preview in UI Builder?

 

The TemplateContainer was originally created for the inspector use-case, so that's why, as @cpalma-unity suggests, it will resize accordingly to the size of its children.

In editor windows and in runtime, you sometimes want a different behaviour by default, which is that your main panel should take all the available space. Out of the box, the TemplateContainer makes it harder to work in that mode, because unless your root elements provide a height or min-height (for example), the TemplateContainer will have a height or 0.

To make sure that the TemplateContainer's size is not 0, you need to either set the height of its children or you need to make the TemplateContainer's size be dependent on the parent, for example by setting the

flex-grow

property of the TemplateContainer to 1.

Note that you can also avoid some of these issues by using

VisualTreeAsset.Clone(parent)

, which will add the content of the uxml file to the parent directly without adding a TemplateContainer.

Hope this helps!