CODEWITHSUNDEEP
c#wpf
Squanchy
Squanchy

Reputation: 87

ActualWidth / ActualHeight of custom control

Sorry to ask this one, as I've found lots of similar questions, yet somehow the solutions that have worked for them don't seem to apply here...

I have a number of custom controls which generate paths (some are static, some are bound to values that update).

I am displaying these on a single itemscontrol (using a canvas as the itemspaneltemplate), and I need to grab the X & Y position of the individual items. XAML for one of the items shown below:

<Style TargetType="{x:Type pg:GraphVertexBelt}">
<Setter Property="Template">
    <Setter.Value>
        <ControlTemplate TargetType="{x:Type pg:GraphVertexBelt}">
            <Border Background="Transparent">
                <StackPanel>
                    <Canvas Width="225" Height="20">
                        <Ellipse Height="10" Width="10" Canvas.Left="10"/>
                        <Ellipse Height="10" Width="10" Canvas.Left="220"/>
                        <Line X1="15" Y1="0.5" X2="225" Y2="0.5"/>
                    </Canvas>
                    <Label Content="{Binding Item.Tag.Title}" HorizontalAlignment="Center"/>
                </StackPanel>
            </Border>
        </ControlTemplate>
    </Setter>
</Setter>

The problem I'm having is that the ActualHeight / ActualWidth are always showing up as zero.

I've Tried:

the reason I need to do this is that the width and height of the elements within the control are actually going to be dynamic, and I need to be able to annotate the diagram at appropriate points relative to the position of actual controls.

Any help would be greatly appreciated!

Cheers.

Edit

maybe I need to explain the intent a little more clearly for this to make sense. I have a zoomable canvas, within which a collection of controls are displayed. Each control needs to be positioned within the canvas, and I need to know the height and width of these controls on the canvas.

Within each control are a series of paths (as per the example code), these are all positioned relative to one another, so I embedded a canvas within the control. the control also has labels, context menus etc.

If there is another more clean way to approach this then I'm all ears :)

Upvotes: 0

Views: 660

Answers (1)

tgpdyk
tgpdyk

Reputation: 1233

I suggest to create your own Canvas and override Measure and Arrange.

public class MyCanvas : Canvas
{
    protected override Size MeasureOverride(Size constraint)
    {
        Size desiredSize = new Size();
        foreach (UIElement child in this.Children)
        {
            // This is your "control" 
            child.Measure(constraint);
            // This is the size of the "control".
            var myControlSize = child.DesiredSize;
        }
        return desiredSize;
    }

    protected override Size ArrangeOverride(Size arrangeSize)
    {
        // When this is called, you should know the DesiredSize of each control
        // and you can decide where each control location relative to the canvas.
        return arrangeSize;
    }
}

Then use MyCanvas as your ItemsPanelTemplate.

WPF Layout

Upvotes: 1

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