Home/ Questions/Q 4270334
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-21T07:17:31+00:00

I have a Canvas with a Grid on it. The Grid contains 3 columns.

  • 0

I have a Canvas with a Grid on it. The Grid contains 3 columns. The first column contains another Grid, the second contains nothing, the third contains an Image (a box). (I have the blank column for animation purposes unrelated to this question.)

In my child Grid I have 2 rows. The first row contains a UserControl (shelves of boxes), the second contains an Image (a barcode).

The problem is that the layout engine seems to completely ignore the dimensions of the user control. In the preview I see my UserControl and directly on top of it the two other images. Granted Canvas doesn’t automatically size its children, but I have that resolved with some resize statements in the SizeChanged event of the page.

As it is, the box shows up at runtime in the bottom right corner of my window as it should, however the barcode appears positioned as if the UserControl doesn’t exist.

For an illustration of my issue please see http://www.wynright.com/temp/Problem.png

The following is my XAML code:

<Canvas x:Name="MainCanvas" Background="Silver">
    <Grid Name="LayoutRoot">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>
        <Grid Name="LayoutChild" Grid.Column="0">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="*" />
            </Grid.RowDefinitions>
            <LightPickDemo:Picker x:Name="PickZone" ZoneCleared="PickZone_ZoneCleared" HorizontalAlignment="Left" VerticalAlignment="Top" />
            <Image Name="BarCode" Source="/LightPickDemo;component/Images/BarcodeScan.png" HorizontalAlignment="Center" Stretch="None" VerticalAlignment="Center" Grid.Row="1" />
        </Grid>
        <Image Name="imgShippingBox" Source="/LightPickDemo;component/Images/Empty-Box.png" VerticalAlignment="Bottom" Stretch="None" Grid.Column="2" />
    </Grid>
</Canvas>

So I wonder what do I need to do to get the UserControl to offer its size for the layout engine. I can see in my designer the size of the control, so clearly the compiler knows that there is size to this control.

I would like the barcode to show centered below the UserControl.

Here is the XAML for the UserControl:

<Canvas>
    <Image Name="ImageBase" Source="/LightPickDemo;component/Images/BayShelves.png" />
    <LightPickDemo:ZoneLight x:Name="ZoneLight" Canvas.Left="345" Canvas.Top="0" ButtonPress="ZoneLight_ButtonPress" />
    <LightPickDemo:PickerModule x:Name="pickerCalculator" Canvas.Left="74" Canvas.Top="266" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerCalendar" Canvas.Left="207" Canvas.Top="266" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerPaperClip" Canvas.Left="521" Canvas.Top="266" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerRuler" Canvas.Left="649" Canvas.Top="266" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerScissor" Canvas.Left="75" Canvas.Top="532" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerStapler" Canvas.Left="250" Canvas.Top="532" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerStapleRemover" Canvas.Left="435" Canvas.Top="532" OnPicked="Picker_PickChanged" />
    <LightPickDemo:PickerModule x:Name="pickerTapeDispenser" Canvas.Left="635" Canvas.Top="532" OnPicked="Picker_PickChanged" />
</Canvas>

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    An answer to my question seems to be to put the following code in my UserControl, however, I can’t imagine this is the best answer and I know it doesn’t allow for screen scaling at all. So please, if anyone knows how to do this correctly, please let me know.

    Thanks to Wallstreet Programmer for leading me to this workaround.

    Protected Overrides Function MeasureOverride(ByVal availableSize As System.Windows.Size) As System.Windows.Size
    Dim bmp As BitmapImage
    bmp = BaseImage.Source
    Return New Size(bmp.PixelWidth, bmp.PixelHeight)
    'Return MyBase.MeasureOverride(availableSize)
End Function
    • 0