在 WPF 中加载 XAML 后访问 UIElement

Question

我有一个 Canvas 从文件中的 XAML 加载填充，使用：

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);

边框包含许多子元素，包括一些用户控件。

XAML 文件的部分片段：

 <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>

当我想访问代码隐藏中的控件时，我无法实际重新挂钩到元素：

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

UI 元素在屏幕上显示良好，但我总是得到“Couldn找不到 Vis”消息。从到目前为止我读到的所有内容来看，只要我的元素是画布中某处的子元素，使用 FindName 就应该有效，对吧？我缺少什么？

谢谢

Answer 1

FindName 通常用于从模板中获取元素。在您的情况下，您可能最好使用 LogicalTreeHelper

LogicalTreeHelper.FindLogicalNode(SBWindowContainerCanvas,
                                   "Vis3DigitScoreControl");

Answer 2

尝试使用该方法：

 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;
                }
            }
        }
    }

它应该返回给您所需的所有对象。之后您将能够在 foreach 循环中选择一个。

Answer 3

尝试使用 x:Name 而不是 Name，并在该元素加载后进行检查。

Answer 4

LogicalTreeHelper.FindLogicalNode(...) 在这里起作用，因为它跨越 NameScope 边界。

而 FindName(...) 在相同的 NameScope 中工作。

动态添加控件需要很好地理解NameScopes。