模板绑定到几何是否可能

Question

我目前有一个自定义Button 控件，它通过ControlTemplate 类型的依赖属性在控件上显示DrawingImage 集。我一直试图将DrawingImage 移动到控制模板中并绑定到Geometry，但失败了。是否可以绑定到Geometry 对象？如果不是，为什么不，如果是，我错过了什么？

下面的截图显示了我在右侧的成功尝试和左侧的失败尝试。

绑定到 DrawingImage 的示例（有效） - generic.xaml：

<Style TargetType="{x:Type local:RoundButton3}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:RoundButton3}">
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="auto"/>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>

                    <Ellipse StrokeThickness="5" Stroke="Green"/>

                    <Viewbox Margin="10" Stretch="Uniform">
                        <ContentControl 
                            Template="{TemplateBinding ImageTemplate}" />
                    </Viewbox>

                    <TextBlock VerticalAlignment="Center" 
                               Grid.Column="1" 
                               Text="Round Button" Margin="5,0,0,0" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

与

public class RoundButton3 : Button
{
    static RoundButton3()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(RoundButton3), 
            new FrameworkPropertyMetadata(typeof(RoundButton3)));
    }

    public static readonly DependencyProperty ImageTemplateProperty =
        DependencyProperty.Register(
            "ImageTemplate", typeof (ControlTemplate), typeof (RoundButton3),
            new FrameworkPropertyMetadata(
                default(ControlTemplate),
                FrameworkPropertyMetadataOptions.AffectsRender |
                FrameworkPropertyMetadataOptions.AffectsMeasure));

    public ControlTemplate ImageTemplate
    {
        get { return (ControlTemplate)GetValue(ImageTemplateProperty); }
        set { SetValue(ImageTemplateProperty, value); }
    }
}

并像这样使用

    <Grid.Resources>
        <GeometryGroup x:Key="AddGeometry">
            <LineGeometry StartPoint="25,12" EndPoint="25,38" />
            <LineGeometry StartPoint="12,25" EndPoint="38,25" />
        </GeometryGroup>

        <ControlTemplate x:Key="RoundAddTemplate">
            <Image SnapsToDevicePixels="True">
                <Image.Source>
                    <DrawingImage>
                        <DrawingImage.Drawing>
                            <DrawingGroup>
                                <GeometryDrawing Pen="{StaticResource RoundButtonPen}" Geometry="{StaticResource AddGeometry}"/>
                            </DrawingGroup>
                        </DrawingImage.Drawing>
                    </DrawingImage>
                </Image.Source>
            </Image>
        </ControlTemplate>
    </Grid.Resources>

   <local:RoundButton3 
        Grid.Column="1"
        Content="RoundButton3" ImageTemplate="{StaticResource RoundAddTemplate}"/>

我尝试绑定到几何资源（不起作用） - generic.xaml：

<Style TargetType="{x:Type local:RoundButton2}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:RoundButton2}">
                    ...

                    <Viewbox Margin="10" Stretch="Uniform">
                        <Image>
                            <Image.Source>
                                <DrawingImage>
                                    <DrawingImage.Drawing>
                                        <DrawingGroup>
                                            <DrawingGroup.Children>
                                                <GeometryDrawing 
                                                  Pen="{StaticResource RoundButtonPen}" 
                                                  Geometry="{TemplateBinding Geometry}" />
                                            </DrawingGroup.Children>
                                        </DrawingGroup>
                                    </DrawingImage.Drawing>
                                </DrawingImage>
                            </Image.Source>
                        </Image>
                    </Viewbox>

                    ...
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

在哪里

public class RoundButton2 : Button
{
    static RoundButton2()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(RoundButton2), 
            new FrameworkPropertyMetadata(typeof(RoundButton2)));
    }

    #region Geometry

    public static readonly DependencyProperty GeometryProperty =
        DependencyProperty.Register(
            "Geometry", typeof (Geometry), typeof (RoundButton2),
            new FrameworkPropertyMetadata(
                default(Geometry),
                FrameworkPropertyMetadataOptions.AffectsRender | 
                FrameworkPropertyMetadataOptions.AffectsMeasure));

    public Geometry Geometry
    {
        get { return (Geometry)GetValue(GeometryProperty); }
        set { SetValue(GeometryProperty, value); }
    }

    #endregion
}

和使用一样

    <local:RoundButton2 
        Grid.Column="0"
        Geometry="{StaticResource AddGeometry}"
        Content="RoundButton2" />

使用前面定义的 AddGeometry 资源。

Answer 1

如果您替换，您的代码应该可以工作

<GeometryDrawing
    Geometry="{TemplateBinding Geometry}" />

通过

<GeometryDrawing
    Geometry="{Binding Geometry, RelativeSource={RelativeSource TemplatedParent}}" />

请参阅this question 了解说明。