[英]WPF, cannot access a control inside a ControlTemplate
我有以下ControlTemplate:
<UserControl x:Class="WpfSinergoHMIControls.Controlli.ControlButton"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfSinergoHMIControls.Controlli"
mc:Ignorable="d">
<UserControl.Template>
<ControlTemplate TargetType="UserControl" x:Name="ControlButtonTemplate">
<Grid Background="Black" Name="ControlButtonGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="1*" />
<RowDefinition Height="2*" />
</Grid.RowDefinitions>
<Label Content="{TemplateBinding Content}" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" Background="White" Margin="1,1,1,1" Grid.Row="0"></Label>
<Viewbox Grid.Row="1" Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center">
<Ellipse Width="100" Height="100" Fill="White" Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" />
</Viewbox>
<Viewbox Grid.Row="1" Margin="5" HorizontalAlignment="Center" VerticalAlignment="Center">
<Ellipse Width="100" Height="100" Margin="0" Name="InnerEllipse" Fill="Black" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Viewbox>
</Grid>
</ControlTemplate>
</UserControl.Template>
我想以編程方式訪問名為'InnerEllipse'的對象。
我嘗試使用以下代碼行:
Ellipse InnerEllipse = (Ellipse) this.Template.FindName("InnerEllipse", this);
在“ControlButton”類中稱為“Color”的屬性內部調用:
public Color Color
{
set
{
Ellipse InnerEllipse = (Ellipse)this.Template.FindName("InnerEllipse", this);
}
}
當我使用'UserControl'時,屬性'Color'會被初始化
<Controlli:ControlButton Height="169" Width="119" Color="DarkGreen"/>
問題是函數“FindName”返回'null'。 我無法弄清楚遺漏了什么。 非常感謝你!
問題是在應用模板之前設置了Color
屬性。
Color
應該是依賴屬性。 然后,您可以指定一個默認值,並連接一個在更改時調用的PropertyChangedCallback
:
public partial class ControlButton : UserControl
{
public ControlButton()
{
InitializeComponent();
}
Ellipse InnerEllipse;
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
InnerEllipse = (Ellipse)this.Template.FindName("InnerEllipse", this);
}
public static readonly DependencyProperty ColorProperty =
DependencyProperty.Register("Color", typeof(Color),
typeof(ControlButton), new FrameworkPropertyMetadata(Colors.DarkGreen, new PropertyChangedCallback(OnColorChanged)));
public Color Color
{
get { return (Color)GetValue(ColorProperty); }
set { SetValue(ColorProperty, value); }
}
private static void OnColorChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ControlButton ctrl = d as ControlButton;
if (ctrl.InnerEllipse != null)
ctrl.InnerEllipse.Fill = new SolidColorBrush() { Color = ctrl.Color };
}
}
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