Here is the sample pseudo XAML code
<Window>
<Grid Rows="2">
<Listbox Row="0"/>
<Button Row="1"/>
</Grid>
</Window>
Grid doesn't work here, just for example
Listbox is databinded and can have multiple items
Button is placed under the ListBox - immediately under, not on bottom of window
Listbox can grow, moving Button down until Button is on bottom of window. Then Listbox gets vertical scrollbar and scrolls its items, with Button remaining on bottom.
I can't remember seeing such layout, and think it can't be done without binding to ActualHeight/using some converter code, which i'm really bad.
Thanks in advance.
Use a StackPanel instead of your Grid.
Related
I have a wpf window defined in XAML as follows:
<Window
[The usual stuff]>
<Window.Resources>
[Some resources]
</Window.Resources>
<DockPanel>
<ToolBarTray>
[Two toolbars]
</ToolBarTray>
<DataGrid>
[Stuff]
</DataGrid>
</DockPanel>
<Window>
The DataGrid has an ObservableCollection as the ItemsSource.
In this configuration, the DataGrid is populated as the user scrolls down through the data rows.
If I change the DockPanel to a StackPanel - and change nothing else - all rows of data are loaded when the window is Loaded.
Why the difference in behavior?
Why the difference in behavior?
The StackPanel disables the UI virtualization of the DataGrid because it measures its child elements with infinite vertical space:
Horizontal scroll for stackpanel doesn't work
XAML/WPF - ScrollViewer which has StackPanel inside is not scrolling
Is it possible to have content behind a scrollviewer that still reacts to user mouse input?
<Grid>
<Button Width="50" Height="50"/>
<ScrollViewer Background="{x:Null}"/>
</Grid>
I've tried combinations of zindexes and null backgrounds, but can't seem to stop the scrollviewer from not tunneling the events down.
To prevent eating clicks, make your scroll viewer non-focusable:
<ScrollViewer Focusable="False" />
The scrollviewer is eating click messages. You don't want to put things behind it.
It would be better to put things inside the scrollviewer. You can make a grid that contains the content and a usercontrol behind the content. The control can be themed to be transparent using a rectangle painted with the color "Transparent". The control would still be clickable, and would still fill up all the space within the scrolled content.
I am building a user control in WPF and put a few buttons in a stackpanel laying inside a grid. Problem is that when I build the app and run it, the buttons "sail around" and don't stay where I put them in the designer window. Is there any attribute I'm missing(or some sort of container?)?
Thanks.
Try setting the alignment properties of your grid:
<Grid HorizontalAlignment="Left" VerticalAlignment="Top">
...
</Grid>
I'm developing an opensource application named Media Assistant. I used a ListBox to show the library. ItemsSource is bound to a list of LibraryItem. Here is the XALM.
<ListBox Name="Tree" DockPanel.Dock="Top"
ItemsSource="{Binding DataSource.OrderedLibraryItems}"
Background="{StaticResource LibraryBackground}"
Width="220" HorizontalAlignment="Left"
BorderThickness="0"
VirtualizingStackPanel.IsVirtualizing="True"
VirtualizingStackPanel.VirtualizationMode="Standard"
ScrollViewer.IsDeferredScrollingEnabled="True"
ItemTemplate="{StaticResource ListLibraryItemTemplate}"
SelectionMode="Single"
MouseDoubleClick="HandleMouseDoubleClick"
/>
The problem is when I show any status message at the bottom of my window from a thread by using Dispatcher.
Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background,new ParameterizedThreadStart(action), state);
The ListBox scrolls to at the top. If I don't show any status message then it works just fine. The datacontext or list items or focus has not been changed. I could not found any reason why it's doing that. It happens when I display any wait screen which is a non modal window. I could not recreate it in a different project. Here is the source code of Media Assistant.
You can easily re-create it by un-commenting the return statement of method SetStatusMessage at BackgroundScanner class.
I found the reason behind this, so the solution.
I used a DockPanel to layout my UI. I put my status bar at the bottom, the ListBox on the Left and other items are on middle and top. There is a TextBlock in my StatusBar which has width and Height set to Auto. So, when I changed text of my StatusBar TextBlock it's width and height gets recalculated and It's parent's recalculates it's layout. Hence the ListBox gets invoked to Measures and Arrange. Even though it's size does not gets changed it resets it's scroll position to top. It happens only if I use ScrollViewer.CanContentScroll="True" at the ListBox. By default it is True. So, even though I did not set this value It was resetting the scroll position. If I disable it by using ScrollViewer.CanContentScroll="False" then it works fine.
<ListBox Name="Tree" DockPanel.Dock="Top"
ItemsSource="{Binding DataSource.OrderedLibraryItems}"
Background="{StaticResource LibraryBackground}"
Width="220" HorizontalAlignment="Left"
BorderThickness="0"
VirtualizingStackPanel.IsVirtualizing="True"
VirtualizingStackPanel.VirtualizationMode="Standard"
ScrollViewer.IsDeferredScrollingEnabled="True"
ScrollViewer.CanContentScroll="False"
ItemTemplate="{StaticResource ListLibraryItemTemplate}"
SelectionMode="Single"
MouseDoubleClick="HandleMouseDoubleClick"
/>
But setting ScrollViewer.CanContentScroll="False" disables virtualization and I want to use virtualization to my ListBox so I set fixed Height and Width to the TextBlock. So, the DockPanel does not re-arrange it's children if I change the status message.
May be it's a bug at ScrollViewer. It should not change the scroll position if the size has not changed.
In reply to #user904627's answer, here is an enhanced version of his workaround. The issue with just fixing Width and Height is the ListBox keeps the same position even if the user resizes the Window. This is not acceptable.
This is why I created this tiny behavior which fixes Width and Height but listens to the parent element's SizeChanged event to let the ListBox resize itself when the container's size changes.
The code is here: VirtualizedListBoxFixBehavior
When the parent element is resized, I restore Width and Height to double.NaN (so the control can resize itself) and I queue the bit of code which fixes the size properties to actual values in the Dispatcher for later execution.
But this still is an ugly working workaround...
Try this:
listBox1.ScrollIntoView(listBox1.Items.GetItemAt(listBox1.Items.Count - 1));
Since the layout is being reset, it is expected that the list box to select the first item (0).
Can you try to set the selected item to the number of existing items in the list box:
Tree.SelectedIndex = Tree.Items.Count;
I did not test this solution on your code but I have used it in another project of mine where I had a similar problem.
Hope it helps.
I have a databound and itemtemplated ListBox:
<ListBox x:Name="lbLista"
ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox IsChecked="{Binding Deleteable, Mode=TwoWay}" />
<Label Content="{Binding Name}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The ites show fine and they come from an ObservableCollection.
The problem is the scrollbar which appears but is not usable - it does not have a handle to grab. I've tried setting some ScrollView attached properties on ListBox, but they do not affect the situation.
I pasted your code into test project, added about 20 items and I get usable scroll bars, no problem, and they work as expected. When I only add a couple items (such that scrolling is unnecessary) I get no usable scrollbar. Could this be the case? that you are not adding enough items?
If you remove the ScrollViewer.VerticalScrollBarVisibility="Visible" then the scroll bars only appear when you have need of them.
ListBox will try to expand in height that is available.. When you set the Height property of ListBox you get a scrollviewer that actually works...
If you wish your ListBox to accodate the height available, you might want to try to regulate the Height from your parent controls.. In a Grid for example, setting the Height to Auto in your RowDefinition might do the trick...
HTH
I have never had any luck with any scrollable content placed inside a stackpanel (anything derived from ScrollableContainer. The stackpanel has an odd layout mechanism that confuses child controls when the measure operation is completed and I found the vertical size ends up infinite, therefore not constrained - so it goes beyond the boundaries of the container and ends up clipped. The scrollbar doesn't show because the control thinks it has all the space in the world when it doesn't.
You should always place scrollable content inside a container that can resolve to a known height during its layout operation at runtime so that the scrollbars size appropriately. The parent container up in the visual tree must be able to resolve to an actual height, and this happens in the grid if you set the height of the RowDefinition o to auto or fixed.
This also happens in Silverlight.
-em-
Thnaks for answer. I tried it myself too to an Empty Project and - lo behold allmighty creator of heaven and seven seas - it worked. I originally had ListBox inside which was inside of root . For some reason ListBox doesn't like being inside of StackPanel, at all! =)
-pom-