How to position WPF Expander based on Header height? - c#

I have been struggling with a problem that at first glance might look easy for quite some time now. The problem in short is that I want to position an expander based on the height of the header in the expander.
The long story is that I have a grid with (currently, but that could be easily changed) two rows. At the bottom at the first row (kind of a header) I would like to put an Expander. However, I would like this expander to expand onto the second row. Simply putting the expander in the first row and setting vertical alignment to bottom positions my expander correctly but brakes the expansion (expands to same row only). Setting Grid.RowSpan="2" makes my expander expand correctly but that brakes my original vertical alignment to the bottom. I've tried putting the expander in the second row and then bind the margin of the expander to the ActualHeight of the expander (along with a converter which gave me a negative top margin equal to the height) which turned out great, until I clicked my expander :-). Setting the binding mode to "OneTime" gave me a zero margin for some reason.
Do anybody have an easy solution for this? Would it help to create a control template for my expander based on a canvas (my thinking is that canvas would be drawn on top of other controls)? I guess I could have done databinding to a descendant control if that was supported (which I don't think it is). Have I missed any obvious solutions?
I have the possibilty to change the control template for the expander and changing the grid layout of my window containing the control is not an issue if that could help me in anyway.
I am running Visual Studio 2008, .NET 3.5.
//daniel

There is a way to make it appear that a single expander has separate layout for its header and content, so they can be in separate grid cells or even totally separate parts of the window. This may be overkill for what you really want to accomplish, but here it is:
Create an expander with your header but an empty body. Place it in the upper cell.
Create another expander with the body you want but set its Template property to a template containing just a ContentPresenter so no header will be visible. Place it in the lower cell.
Bind the second expander's IsExpanded property to the first expander's IsExpanded property
Optionally adjust tab order so the two Expanders are together
Now when you expand the upper expander the lower expander will expand as well. If there is no gap between them, they will appear as if they were a single expander.
Another option which may be effective is to use a single Expander and modify its template so its entire header (including the button) has VerticalAlignment="Bottom" and is inside a zero-size Canvas. In that case the entire Expander would go in your lower cell. This has the disadvantage that layout of the upper cell would be unaware of the space used by the Expander so it would likely place other controls over or under it depending on the z-order.

Related

Arranging Grid items depending on other items' visibility

I have a Panel that shows Labels, TextBoxes, and ComboBoxes and the code behind sets the visibility to visible or collapsed depending upon the user's choice from a ComboBox outside of said Panel. What would be the best way to eliminate the gaps in the Panel, and to get all of the items that are visible to the right side of the grid (decrease the column position if there are empty cells at the bottom of the previous column)? What type of Panel should I use? Should I split them into separate panels?
Edit:
Here is a poor Excel interpretation of what i would like to happen: http://imgur.com/ZVRh6Yq
I essentially want to make everything go to the top left corner
It's hard to understand your layout without some diagram or sketch, but I think you can stay with the Grid layout if you set the row height/column width to "auto". This will cause each grid row/column to be large just enough to present its own content.
You can also use other layout types such as StackPanel or DockPanel, they give you less control over the positioning of your controls, but provide comfortable automatic layout.
EDIT:
You can use a WrapPanel to get the expected results:
<WrapPanel Orientation="Vertical">
<Label/>
<TextBox/>
<ComboBox/>
</WrapPanel>

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So if there's just one character within it it'll be a small width.
And if there's a long word within it it'll be a long width, etc.
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That is the default behavior of a TextBox, however the parent panel for the TextBox can affect a TextBox's size.
For example, a Grid will automatically stretch it's children to fill all available space. A DockPanel will do the same with the Last Child added to it, unless LastChildFill=False.
You can overwrite this behavior in the parent panel by setting the HorizontalAlignment of the TextBox. For example, setting HorizontalAlignment="Center" will center the TextBox inside a Grid rather than stretching it to fill all remaining space
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Just ran into a bunch of random but probably very simple questions while learning to work with WPF. If anyone can answer any of these it would be most appreciated.
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For a simple table layout Grid is the way to go. Is your problem that you need it to be dynamic? If so, you can create multiple grids with SharedSizeGroup on the columns to make them look like a single grid. See: How to align separate Grids created via templates along their columns / rows?
Learn about creating your own templates!
Not that I know of, but it would be relatively simple to do, create a storyboard that scales the item on mouse over.
No idea ... running out of steam!
As Andrzej Nosal mentioned, these really should be separate questions!

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I have this:
Each list is its own WrapPanel and they are all on another WrapPanel which is in a ScrollViewer. If I don't set the height myself for the main WrapPanel it assumes I want the WrapPanel as high as it can go giving me only one column whereas I want as many columns as needed to fill the window.
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In your example screen shot and description I see a tab control whose anchor is set to Top, Left, Bottom, and Right. The tab page with AutoScroll set to true. Within the tab page I see a FlowLayoutPanel. The FlowLayoutPanel has its AutoSize property set to true. I also see a set of other panels/user controls each of which contains a title and a series of check boxes.
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<ControlTemplate TargetType="controls:TreeViewItem">
<Grid Background="{x:Null}" Margin="0,-4,0,-4">
...

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