I've put an Expander onto a Page. Within the expander there is a Label. After the page is loaded, the expander is not yet expanded. At this point, I inspect the Expander using VisualTreeHelper, I got a structure like this:
Expander
Border
DockPanel
ToggleButton
Border
Grid
Ellipse
Ellipse
Path
ContentPresenter
ContentPresenter
where there is no Label under the last ContentPresenter.
However, Once the expander is expanded and then collapsed, I got the a different structure using VisualTreeHelper:
Expander
Border
DockPanel
ToggleButton
Border
Grid
Ellipse
Ellipse
Path
ContentPresenter
ContentPresenter
Label
Border
ContentPresenter
This time, the Label appears under the ContentPresenter.
It seems that as long as the expander has been expanded, VisualTreeHelper will know the contents within the Expander. But is there a possible way to make VisualTreeHelper be aware of Expander's contents without expanding it?
Thanks.
There is a method for forcing a control to load its contents programmatically.
I imagine you have some sort of recursive loop that searches through your elements. Before you call to get its children, use this call:
if (element is FrameworkElement)
(element as FrameworkElement).ApplyTemplate()
That'll force it to apply its template and load the controls into memory. I imagine it is done this way for performance reasons, as controls are not normally needed until they are visible.
This approach also works for TabControl and any other control that can hide content, I believe.
Credit goes to Tao Liang who posted this solution over here. Read it also if you're having trouble with your recursive loop.
Related
I'm showing various objects inside a ListBox.
Each object have adorners that can be shown in particular cases.
If an adorner is shown, it should be visible even if the size of the ListBoxItem holding my object is less than the size of the adorner; unfortunately at the moment the adorner hides behind the ListBoxItem if it gets too small.
How can i force the adorner to be always on top of the z-order or alternatively how can i avoid to be clipped to the bounds of the ListBoxItem?
I would expect your adorners to be clipped by the ListBox, not the ListBoxItem. It sounds like you may be adding an AdornerDecorator to your item content or item template. If that's the case, try removing it and letting the adorners be shown in the layer owned by the list box's ScrollViewer. That should remove the clipping at the item bounds but still clip adorners that extend beyond the viewport.
I'm writing the WPF app that uses TreeView control inside the UserControl. TreeView control has the same width as the UserControl.
The problem is that I need to make the children nodes to have the full with of the TreeView. I can't assign the width by the static expression as well as UserControl that contains TreeView may have variable width.
I thought that the solution can be reached by assigning the TreeView child item the width of the UserControl. But if I do so the TreeView child item will be out of control, as well as there is margin in the children item. For example
Item A
---Item B
Can you tell, how can I get the width of --- ? Or to make ItemB be under the Item A without using static margin metrics?
Thank you
You can edit the Style of TreeViewItem and make its Horizontal Alignment as Stretch instead of Left. Also ensure you host your ContentPresenter inside the Grid.
In this case, eventhough the header text seems to be leeser in width, the mouse hover or Selected color will cover the entire width of treeview. I hope that is what you need.
I have a silverlight expander control which wraps a grid. In the grid, I have a number of text boxes, combo boxes as well as some invisable (collapsed) text blocks. I also have an animation and when it is triggered the grid shows those hidden text blocks.
My problem is, when the hidden text blocks are shown after the animation is run, these text blocks push other controls down and because the expander doesn't resize itself, the controls at the bottom get pushed outside of the expander and become invisible.
I tried to call UpdateLayout() after the SizeChanged event of the grid but doesn't work.
Any suggestions on how to resolve this issue would be much appreciated!!
I actually have fixed this problem by myself. I discovered in the style of the expander control, a while ago I put an ExpandableContentControl instead of normal ContentControl because it has a nice animation when you expand/collpase it. But this control doesn't resize properly... (see http://silverlight.codeplex.com/workitem/4544?ProjectName=silverlight) I guess this is why the AccordionItem control is so buggy because it also has an ExpandableContentControl in it. As soon as I replaced the ExpandableContentControl with a normal ContentControl, the expander worked as expected. :)
The problems is because the expander always use the same width (or height), so you must recalculate the width of the grid by code and assign it to the columndefinition.
I have some controls added in a stackpanel programmatically. What i want to do is that i want one of the controls in this stackpanel to be placed over another control. Specifically, I want to place button over an image in this stack panel. I couldn't find zindex property in c# codebehind. Although it seems very simple problem but i am unable to find any clue to solve this problem. Anyone please......??
Try placing all your controls on Canvas. Then you can set Zindex with:
this.controlName.SetValue(Canvas.ZIndexProperty, 10d);
Only the Canvas panel supports a ZIndex property. Stackpanel doesn't because each item is placed one after the other in the panel so they shouldn't overlap each other. This can be a little annoying at times when you have animated transforms moving the items about because the previous assumption isn't actually true.
In general though if you need to place items in a visual stack the Stackpanel isn't the right place for it. Perhaps a Canvas or you could use a Grid where the oridinal position of a element determines its "zorder" in a cell.
From xaml:
<StackPanel Canvas.ZIndex="1">
</StackPanel>
I'm using a DataTemplate that animates a RenderTransform to increase its size when the mouse is over it. The problem I'm having is that when the animation is in effect the enlarged list box item appears behind other items. Is there a way to control the ZIndex of the list box item from within my DataTemplate so that it's always on top of other items?
You can set the Templated Element's ZIndex from template using Triggers. Find out the templated parent control by VisualTree parsing like bellow
{RelativeSource FindAncestor,AncestorType=...
The zIndex is only available on elements hosted inside a Canvas. Therefore you may be able to wrap the whole listbox control in a canvas then set Canvas.zIndex to 99 as part of the Trigger you are using to do the transform . However I could not get this to work.
The only other option that did work is to use a LayoutTransform rather than a RenderTransform as this will move the other items out of the way as the transform is calculated before the items are placed. This would mean there would be no need to set any zIndex, however it would depend on your requirements.