CODEWITHSUNDEEP
c#wpfxaml
Harkonnen
Harkonnen

Reputation: 813

Can't access to the content of a ControlTemplate from code behind

Here is my XAML. The UserControl is named "Event"

<UserControl.Resources>
    <Style x:Key="eventStyle" TargetType="Thumb">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Thumb}">
                    <Rectangle Name="rect" Fill="CadetBlue" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</UserControl.Resources>

<Canvas>
   <Thumb Canvas.Left="0" Canvas.Top="0" Name="MoveThumb" Style="{StaticResource eventStyle}" Cursor="SizeAll" DragDelta="MoveThumb_DragDelta" DragStarted="MoveThumb_DragStarted" DragCompleted="MoveThumb_DragCompleted" />
</Canvas>

And here is the code behind

var ev = new Event();
var rect = ev.Template.FindName("rect", ev) as Rectangle;

But it doesn't work : the "rect" variable is null. What am I doing wrong ?

Thanks

Upvotes: 0

Views: 993

Answers (2)

Adi Lester
Adi Lester

Reputation: 25201

The template you're defining is applied to the Thumb control, and not the Event control - that's why there's no rect control in Event's template.

Since you're creating the Event control from another class, what you can do is expose the MoveThumb control as a property in Event's code-behind, like this:

public Thumb TheThumb
{
    get { return MoveThumb; }
}

Then you can change your code to this:

var ev = new Event();
var rect = ev.TheThumb.Template.FindName("rect", ev.TheThumb) as Rectangle;

Better yet, you can expose the rect control as a property:

public Rectangle Rect
{
    get { return MoveThumb.Template.FindName("rect", MoveThumb) as Rectangle; }
}

and use it like this

var ev = new Event();
var rect = ev.Rect;

Upvotes: 2

Toan Nguyen
Toan Nguyen

Reputation: 11591

It returned null because the function FindName("controlName",TemplatedParent) expects a control on which the template is applied as the second parameter. From the code you've provided, I couldn't see when the template was applied to the control (ev used to the default template). Hence, the rect variable was null.

Try this 

var rectangle = MoveThumb.Template.FindName("rect", MoveThumb) as Rectangle;

More information is available here and here

Upvotes: 1

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