Get the Height of the WPF Expander Header

Question

I need to get the Height of the WPF Expander.Header, not the whole Expander just the Height of the Header.

There is no property to get it because the Expander.Header + Expander.Content is the Expander.Height.

What would you do to get the Expander.Header Height ?

Mykola Bohdiuk · Accepted Answer · 2010-12-26T09:21:28.897

5

If your expander isn't templated, that's a Visual tree:

Expander { Border { DockPanel { ToggleButton, ContentPresenter {...} } } }

All you need is to get that ToggleButton. It's easy using VisualTreeHelper:

var border = VisualTreeHelper.GetChild(expander, 0);
var dockpanel = VisualTreeHelper.GetChild(border, 0);
var togglebutton = VisualTreeHelper.GetChild(dockpanel, /*0*/); // it may be not 0th, so please enumerate all children using VisualTreeHelper.GetChildrenCount(dockpanel) and find that ToggleButton
return togglebutton.ActualHeight;

Edit

Also, I'd like to accent on using ActualHeight, not Height, because Height is not double.IsNaN (in XAML, auto) only if set explicitly in code or XAML

edited Dec 26 '10 at 09:21

answered Dec 25 '10 at 22:25

Mykola Bohdiuk

1,307
12
16

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same I found on msdn forum now looks ok :) prolly you found this link too? :P => http://social.msdn.microsoft.com/Forums/en/wpf/thread/a90b752a-6200-4542-8ec8-29cb902b8aa7 – Elisabeth Dec 26 '10 at 21:07
No, I didn't. Just investigated the visual tree - that's first what I do when some info about element's structure is needed – Mykola Bohdiuk Dec 26 '10 at 21:15

score 3 · Answer 2 · answered Dec 25 '10 at 22:13

I don't know of a way to do that exactly (maybe through reflection?), but you could try using two expanders. One with just a header and one with just a ContentPresenter. You could bind the IsExpanded property of the first expander to the IsExpanded property of the second one. This would make them appear to be a single expander.

I'm not sure exactly what you're trying to accomplish though.

Get the Height of the WPF Expander Header

2 Answers2