Develop Reference

How do you use StackPanel.FindName in WPF?

I have a stack panel with a set of four image buttons inside of it. When I try to search by the name of the image button it comes back null. What is wrong with my code?
XAML:
<StackPanel x:Name="swatchClearStackPanel" Orientation="Vertical" Grid.Column="1" Grid.Row="2" Margin="0,10,0,0" HorizontalAlignment="Left" VerticalAlignment="Bottom">
<imgbutton:ImageButton x:Name="ClearSwatchColor1" Grid.Row="0" Grid.Column="2" Style="{DynamicResource ButtonClearSwatchColor}" Margin="5,8,5,5" HorizontalAlignment="Left" Visibility="Hidden" Click="ClearSwatchColor_Click" />
<imgbutton:ImageButton x:Name="ClearSwatchColor2" Grid.Row="0" Grid.Column="2" Style="{DynamicResource ButtonClearSwatchColor}" Margin="5,18,5,5" HorizontalAlignment="Left" Visibility="Hidden" Click="ClearSwatchColor_Click"/>
<imgbutton:ImageButton x:Name="ClearSwatchColor3" Grid.Row="0" Grid.Column="2" Style="{DynamicResource ButtonClearSwatchColor}" Margin="5,18,5,5" HorizontalAlignment="Left" Visibility="Hidden" Click="ClearSwatchColor_Click"/>
<imgbutton:ImageButton x:Name="ClearSwatchColor4" Grid.Row="0" Grid.Column="2" Style="{DynamicResource ButtonClearSwatchColor}" Margin="5,20,5,5" HorizontalAlignment="Left" Visibility="Hidden" Click="ClearSwatchColor_Click"/>
</StackPanel>
And the C#:
EDIT: Note: The button name is hard coded to show that it cannot find it, the end result will be a variable as its one method that several buttons will reference. This code triggers after the UI has loaded. (The user clicks a button and this code runs. Same window, same everything.)
var swatchClearButton = swatchClearStackPanel.FindName("ClearSwatchColor1");

set visibility of image dynamically in expanderview

I am trying to implement something where I need to display list of people and a green icon if they are online. these people are grouped by some categories. I am using an expanderview toolkit control to display the list. So how do I set the icon image to be visible dynamically ? I have tried something like this which didnt work.
<DataTemplate x:Key="groupsItemTemplate">
<StackPanel Orientation="Horizontal" Margin="30,5,0,0"">
<Image Height="30" Width="30" Source="/Assets/Online.png" Margin="10,5,0,0" Visibility="{Binding IsFriendOnline}"></Image>
<TextBlock TextWrapping="NoWrap" FontFamily="Segoe WP Light" FontSize="24" Margin="8,0,0,0" VerticalAlignment="Center" HorizontalAlignment="left" Height="auto" Width="300" Text="{Binding FriendName}"></TextBlock>
</StackPanel>
</DataTemplate>
IsFriendOnline is an integer property.

Firstly, you need to use a converter in order to convert the value of your IsFriendOnline property to the Visibility enum that you require.
WPF has a "BooleanToVisibilityConverter" built in so if you have the ability to change the IsFriendOnline to a boolean value (which sounds like it makes a little more sense anyway) I would go down this route... if its imperative that the property is an integer then you will need to roll your own converter which isnt difficult.
The syntax would look something like this when you have a converter (my code below assumes IsFriendOnline is a boolean)...
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<DataTemplate x:Key="groupsItemTemplate">
<StackPanel Orientation="Horizontal" Margin="30,5,0,0"">
<Image Height="30" Width="30" Source="/Assets/Online.png" Margin="10,5,0,0" Visibility="{Binding IsFriendOnline, Converter={StaticResource BooleanToVisibilityConverter}}"></Image>
<TextBlock TextWrapping="NoWrap" FontFamily="Segoe WP Light" FontSize="24" Margin="8,0,0,0" VerticalAlignment="Center" HorizontalAlignment="left" Height="auto" Width="300" Text="{Binding FriendName}"></TextBlock>
</StackPanel>
</DataTemplate>
Hope this helps...

WPF DataTemplate method binding with parameter

I have a custom ItemTemplate for a ListBox and I need to "bind" a TextBlock to some special method / property.
My ListBox Source is an ObservableCollection<SearchResultItem>. SearchResultItem containing some properties.
The text need to change based on the value of another object. E.G if this object equals "foo" I need the text value to call the method GetProperty("foo") on the SearchResultItem to get the correct value.
Here is a sample of code:
<DataTemplate>
..
//Here is a Label bound to the Date Property of the SearchResultItem
<Label Margin="2,2,2,0" Grid.Row="0" Grid.Column="2" Content="{Binding Path=Date}" HorizontalAlignment="Right" HorizontalContentAlignment="Right" />
//Here is the textblock that needs to call the method with the parameter based on the value of the other object.
<TextBlock Margin="2,2,2,0" TextTrimming="CharacterEllipsis" Grid.Row="0" Grid.Column="1" Text="I need some help there" HorizontalAlignment="Left" VerticalAlignment="Center" Foreground="Black"/>
..
</DataTemplate>
Do you have any idea on how to do that or a better way to do it?
Edit:
-Let's assume SearchResultItem comes from an external library and only exposes the GetProperty method.
-Let's say the "foo" value comes from ConfigurationManager.AppSettings["propertyName"]; if it helps.

OK, because your properties never change, here's one solution. You can do this via another property on your SearchResultItem class:
public string MyTextBinding
{
get
{
return myDictionary.ContainsKey("foo") ? return myDictionary["foo"] : return "myDictionary doesn't contain foo";
}
}
Then just bind your textbox to this property:
<DataTemplate>
<Label Margin="2,2,2,0" Grid.Row="0" Grid.Column="2" Content="{Binding Path=Date}" HorizontalAlignment="Right" HorizontalContentAlignment="Right" />
<TextBlock Margin="2,2,2,0" TextTrimming="CharacterEllipsis" Grid.Row="0" Grid.Column="1" Text="{Binding Path=MyTextBinding, Mode=OneWay}" HorizontalAlignment="Left" VerticalAlignment="Center" Foreground="Black"/>
</DataTemplate>

Just use a IValueConverter that takes a SearchResultItem and return the expected text
<TextBlock Margin="2,2,2,0" TextTrimming="CharacterEllipsis"
Grid.Row="0" Grid.Column="1"
Text="{Binding Path=.,
Converter={StaticResource PropertyValueFromSearchResultItemConverter},
ConverterParameter=Foo}"
HorizontalAlignment="Left" VerticalAlignment="Center" Foreground="Black"/>

Listbox extending off the page

I have a listbox inside of a stack panel inside of a border in a silverlight application and when ever I add anything to the listbox it increases in height so the scrollbar is never used and it extends beyond the boundaries of the border element. I have tried explicitly setting the height attribute of the listbox, the border and the stack panel and it still goes beyond this.
Here is my code:
<Border x:Name="articlePane">
<StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Top">
<Button Content="Latest" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
<Button Content="Pending" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
<Button Content="Done" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
</StackPanel>
<ListBox x:Name="articleList" Margin="5" Background="Transparent" ItemsSource="{Binding}"
ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical" VerticalAlignment="Top" HorizontalAlignment="Center">
<Image x:Name="articleImage" />
<TextBlock x:Name="articleTitle" Text="{Binding Path=Title}" FontSize="18" FontWeight="Bold"
Margin="5"/>
<TextBlock x:Name="articleDate" Text="{Binding Path=Date}" FontSize="14" Foreground="Gray"
Margin="5"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</Border>

I have a feeling that the StackPanel just keeps on adding height forever. I think in this instance you'd be better off with a Grid layout within your Border. Put the Button StackPanel in one height defined row, and the ListBox in an autosizing * height row. This way Grid will stick within the confines of your form.

How to change datatemplate through code

I have ListBox and DataTemplate
I need Set GroupBox Heigth = 300
How to do it?
<DataTemplate x:Key="data_template">
<GroupBox Header="Категория" Width="300" HorizontalAlignment="Stretch" x:Name="GroupBox">
<DockPanel Tag="{Binding id}">
<Button Click="Button_Click" DockPanel.Dock="Top" >
<Button.Content>
<DockPanel>
<TextBlock Text="{Binding title}" TextWrapping="Wrap" DockPanel.Dock="Top" Padding="5" HorizontalAlignment="Center" Foreground="#FFB51414" />
<l:ScrollViewerEx VerticalScrollBarVisibility="Auto" >
<TextBlock Text="{Binding description}" DockPanel.Dock="Top" TextWrapping="Wrap" Padding="5" IsHitTestVisible="False" />
</l:ScrollViewerEx>
</DockPanel>
</Button.Content>
</Button>
</DockPanel>
</GroupBox>
</DataTemplate>

In case, someone tried to resolve my previous question, I did it like the following:
DataTemplate mycolumnDataTemplate = null;
var dataTemplateStream = new SomeClass().GetType().Assembly.GetManifestResourceStream("Some.Namespace.SomeReosurceName.xaml");
string dataTemplateString = new System.IO.StreamReader(dataTemplateStream).ReadToEnd();
dataTemplateString = dataTemplateString.Replace("[0]", browserColumn.ColumnName);
mycolumnDataTemplate = XamlReader.Load(dataTemplateString) as DataTemplate;

What are you trying to achieve? Do you want the GroupBox Height to be changed at the runtime of your application, when some event occurred or some data has changed? If so, then what you are probably looking for is a data trigger or event trigger, which you simply need to add to your DataTemplate.