WPF: How to properly override the methods when creating custom control
- by EV
Hi,
I am creating a custom control Toolbox that is derived from ItemsControl. This toolbox is supposed to be filled with icons coming from the database. The definition looks like this:
public class Toolbox : ItemsControl
{
protected override DependencyObject GetContainerForItemOverride()
{
return new ToolboxItem();
}
protected override bool IsItemItsOwnContainerOverride(object item)
{
return (item is ToolboxItem);
}
}
Toolboxitem is derived from ContentControl.
public class ToolboxItem : ContentControl
{
static ToolboxItem()
{
FrameworkElement.DefaultStyleKeyProperty.OverrideMetadata(typeof(ToolboxItem), new FrameworkPropertyMetadata(typeof(ToolboxItem)));
}
}
Since the number of icons stored in a database is not known I want to use the data template:
<DataTemplate x:Key="ToolBoxTemplate">
<StackPanel>
<Image Source="{Binding Path=url}" />
</StackPanel>
</DataTemplate>
Then I want the Toolbox to use the template.
<Toolbox x:Name="NewLibrary" ItemsSource="{Binding}" ItemTemplate="ToolBoxtemplate">
</Toolbox>
I'm using ADO.NET entity framework to connect to a database. The code behind:
SystemicsAnalystDBEntities db = new SystemicsAnalystDBEntities();
private void Window_Loaded(object sender, RoutedEventArgs e)
{
NewLibrary.ItemsSource = from c in db.Components select c;
}
However, there is a problem. When the code is executed, it displays the object from the database (as the ItemSource property is set to the object from the database) and not the images. It does not use the template. When I use the static images source it works in the right way
I found out that I need to override the PrepareContainerForItemOverride method.But I don't know how to add the template to it.
Thanks a lot for any comments.
Additional Information
Here is the ControlTemplate for ToolboxItem:
<ControlTemplate TargetType="{x:Type s:ToolboxItem}">
<Grid>
<Rectangle Name="Border"
StrokeThickness="1"
StrokeDashArray="2"
Fill="Transparent"
SnapsToDevicePixels="true" />
<ContentPresenter Content="{TemplateBinding ContentControl.Content}"
Margin="{TemplateBinding Padding}"
SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver"
Value="true">
<Setter TargetName="Border"
Property="Stroke"
Value="Gray" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
