Accessing UIElement after XAML Load in WPF

Question

I have a Canvas being populated from a XAML load from a file using:

SBWindowContainerCanvas.Children.Clear();          
StreamReader stringreader = new StreamReader("C:\\xaml\\xmltest.xaml");
XmlReader xmlreader = XmlReader.Create(stringreader);

var mainborder = XamlReader.Load(xmlreader);                     
SBWindowContainerCanvas.Children.Add((Blacklight.Controls.ClippingBorder)mainborder);

The border contains many child elements including some user controls.

partial snippet of XAML file:

 <av:ContentControl Name="VisScoreCC" Width="417" Height="228" IsHitTestVisible="True" av:Canvas.Left="855" av:Canvas.Top="8" av:Selector.IsSelected="False">
  <fsp:Scores3DigitControl Name="Vis3DigitScoreControl" VisitorControl="True" OperatorControl="True" NumericValue="4" UseGradientMainBG="False" UseGradientNumberBG="False" UseGradientLogoBG="False" UseGradientTeamNameBG="False" UseRadialMainBG="False" UseRadialNumberBG="False" UseRadialLogoBG="False" UseRadialTeamNameBG="False" UseImageStringMainBG="False|none|False|Tile|Top Left|1" SolidColorMainBG="#FFD4D2D2" SolidColorNumberBG="#FF000000" SolidColorBannerBG="#FF000000" FGColorNumbers="#FFFF0000" FGColorTeamName="#FFFFFFFF" FGColorBanner="#FFFFA500" SolidColorImageLogoBG="#FF000000" SolidColorTeamNameBG="#FF000000" GradientMainBG="#FF000000|#FF808080|#FFFFFFFF" GradientNumberBG="#FF000000|#FF808080|#FFFFFFFF" GradientLogoBG="#FF000000|#FF808080|#FFFFFFFF" GradientTeamNameBG="#FF000000|#FF808080|#FFFFFFFF" GradientOffsetsMainBG="0|0.5|1" GradientOffsetsNumbersBG="0|0.5|1" GradientOffsetsLogoBG="0|0.5|1" GradientOffsetsTeamNameBG="0|0.5|1" LinearAngleMainBG="180" LinearAngleNumberBG="180" LinearAngleLogoBG="180" LinearAngleTeamNameBG="180" OffSegmentOpacity="0.1" RoundRadiusNumbers="0" RoundRadiusLogo="0" RoundRadiusTeamName="0" PosSizeStringNumbers="180|8|200|150" PosSizeStringLogo="20|10|150|150" PosSizeStringTeamName="25|165|360|60" TeamNameFontString="Arial|40|True" UseRightSideBanner="True" Style="{av:DynamicResource Scores3DigitControlTemplate}" Height="Auto" Margin="0,0,0,0" IsHitTestVisible="True" />
</av:ContentControl>
<av:ContentControl Name="HomeScoreCC" Width="417" Height="228" IsHitTestVisible="True" av:Canvas.Left="11" av:Canvas.Top="8" av:Selector.IsSelected="False">
  <fsp:Scores3DigitControl Name="Home3DigitScoreControl" VisitorControl="False" OperatorControl="True" NumericValue="4" UseGradientMainBG="False" UseGradientNumberBG="False" UseGradientLogoBG="False" UseGradientTeamNameBG="False" UseRadialMainBG="False" UseRadialNumberBG="False" UseRadialLogoBG="False" UseRadialTeamNameBG="False" UseImageStringMainBG="False|none|False|Tile|Top Left|1" TargetElementIndex="0" SolidColorMainBG="#FFD4D2D2" SolidColorNumberBG="#FF000000" SolidColorBannerBG="#FF000000" FGColorNumbers="#FFFF0000" FGColorTeamName="#FFFFFFFF" FGColorBanner="#FFFFA500" SolidColorImageLogoBG="#FF000000" SolidColorTeamNameBG="#FF000000" GradientMainBG="#FF000000|#FF808080|#FFFFFFFF" GradientNumberBG="#FF000000|#FF808080|#FFFFFFFF" GradientLogoBG="#FF000000|#FF808080|#FFFFFFFF" GradientTeamNameBG="#FF000000|#FF808080|#FFFFFFFF" GradientOffsetsMainBG="0|0.5|1" GradientOffsetsNumbersBG="0|0.5|1" GradientOffsetsLogoBG="0|0.5|1" GradientOffsetsTeamNameBG="0|0.5|1" LinearAngleMainBG="180" LinearAngleNumberBG="180" LinearAngleLogoBG="180" LinearAngleTeamNameBG="180" OffSegmentOpacity="0.1" RoundRadiusNumbers="0" RoundRadiusLogo="0" RoundRadiusTeamName="0" PosSizeStringNumbers="35|8|200|150" PosSizeStringLogo="250|10|150|150" PosSizeStringTeamName="25|165|360|60" TeamNameFontString="Arial|40|True" UseRightSideBanner="False" Style="{av:DynamicResource Scores3DigitControlTemplate}" OverridesDefaultStyle="False" Name="Home3DigitScoreControl" Height="Auto" IsHitTestVisible="True" />
</av:ContentControl>

When I want to get access to my controls in code-behind, I am not able to actually re-hook to the elements using:

Scores3DigitControl Vis3DigitScoreControlC = (Scores3DigitControl)SBWindowContainerCanvas.FindName("Vis3DigitScoreControl");
if (Vis3DigitScoreControlC == null)
{
    MessageBox.Show("Couldn't Find Vis");
}
else
{
    Vis3DigitScoreControlC.Visibility = Visibility.Hidden;
}

The UI Elements show up fine on the screen but I always get a "Couldn't Find Vis" message. From everything I read so far, using the FindName should work as long as my element is a child somewhere in the canvas, right? What am I missing?

Thank you

@evanb: Actually, i just tried to add some, it ain't pretty either... — H.B., May 26 '11 at 00:02

Simon Fox · Accepted Answer · 2011-05-26T00:28:09.120

4

FindName is generally used for getting elements from a template. In your case your probably best to use the LogicalTreeHelper

LogicalTreeHelper.FindLogicalNode(SBWindowContainerCanvas,
                                   "Vis3DigitScoreControl");

edited May 26 '11 at 00:28

answered May 26 '11 at 00:14

Simon Fox

10,409
7
60
81

Brilliant! That was the answer! I added a little to scope it to my UC: Scores3DigitControl x = LogicalTreeHelper.FindLogicalNode(SBWindowContainerCanvas, "Vis3DigitScoreControl") as Scores3DigitControl; and it works perfectly. Thank You! – sunriser May 26 '11 at 00:29
Still learning formatting on here. Hopefully this looks better: `Scores3DigitControl x = LogicalTreeHelper.FindLogicalNode(SBWindowContainerCanvas, "Vis3DigitScoreControl") as Scores3DigitControl;` – sunriser May 26 '11 at 00:36

score 1 · Answer 2 · answered Jan 31 '17 at 19:27

Try to use that method:

 public IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
    {
        if (depObj != null)
        {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
            {
                DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
                if (child != null && child is T)
                {
                    yield return (T)child;
                }

                foreach (T childOfChild in FindVisualChildren<T>(child))
                {
                    yield return childOfChild;
                }
            }
        }
    }

It should return to you all object which you need. And after you will be able choose one in foreach loop.

score 0 · Answer 3 · answered Sep 18 '16 at 18:22

0

LogicalTreeHelper.FindLogicalNode(...) works here, because it goes across NameScope boundries.

Whereas FindName(...) works in same NameScope.

Dynamically adding controls require good understanding of NameScopes.

answered Sep 18 '16 at 18:22

AnjumSKhan

9,647
1
26
38

score 0 · Answer 4 · answered May 25 '11 at 23:55

0

Try using x:Name instead of Name and checking after that element has loaded.

answered May 25 '11 at 23:55

evanb

3,061
20
32

Accessing UIElement after XAML Load in WPF

4 Answers4