WPF用户控件-将DependencyProperty的默认值设置为Child [英] WPF Usercontrol - setting Default-Value of DependencyProperty to Child

问题描述

嗨社区，

我创建了一个用户控件"Splitter".

xaml看起来像这样:

Hi Community,

I''ve created an usercontrol ''Splitter''.

xaml looks like this:

<UserControl x:Class="DesktopApp.UserControls.Splitter"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <Border x:Name="oBorder">
            
            <Border.Effect>
                <DropShadowEffect x:Name="oShadow" />
            </Border.Effect>
            
        </Border>
</UserControl>

我想访问oBorder和oShadow-Childs的某些属性.

例如，我要像这样设置子级"oBorder"的颜色属性:

I want to access some Properties of the oBorder and oShadow-Childs.

For example i want to set the Color-Property of the Child "oBorder" like this:

<uc:Splitter x:Name="oSplitter" SplitterColor="Orange"></uc:Splitter>

uc定义如下:

where uc is defined as following:

xmlns:uc="clr-namespace:DesktopApp.UserControls"

因此，我已将名为"SplitterColor"的DP放​​入我的用户控件.

So I''ve put a DP called ''SplitterColor'' into my usercontrol.

public Brush SplitterColor
        {
            get { return (Brush)GetValue(SplitterColorProperty); }
            set { SetValue(SplitterColorProperty, value); }
        }

我已定义默认值"Brushes.White"

I''ve defined a default value ''Brushes.White''

public static readonly DependencyProperty SplitterColorProperty =
            DependencyProperty.Register("SplitterColor", typeof(Brush), typeof(Splitter), new PropertyMetadata(Brushes.White, OnSplitterColorChanged));

这段代码更改了oBorder Child的颜色属性.在此示例中，dNewBackgroundColor将是橙色画笔.

This code changes the Color-Property of by oBorder Child. In this example dNewBackgroundColor will be an Orange brush.

private static void OnSplitterColorChanged(DependencyObject sender, DependencyPropertyChangedEventArgs eventArgs)
        {
            Brush dNewBackgroundColor = eventArgs.NewValue as Brush;
            Splitter oThis;

            if (dNewBackgroundColor != null)
            {
                oThis = sender as Splitter;

                if (oThis != null)
                {
                    //Zuweisung
                    oThis.oBorder.Background = dNewBackgroundColor;
                }
            }
        }

效果很好！

但是，如果我将控件定义如下:

It works fine !

But if i define my control as the following:

<uc:Splitter x:Name="oSplitter" SplitterColor="White"></uc:Splitter>

或

or

<uc:Splitter x:Name="oSplitter"></uc:Splitter>

我的程序不会进入我的OnSplitterColorChanged-handler.所以我的颜色不会设置为我的oBorder Child.

将我的依赖项属性的默认值设置给孩子的默认方法是什么?

Jeff

my programm will not step into my OnSplitterColorChanged-handler. So my color will not be set to my oBorder Child.

What''s the default way to set the default value of my dependency-property to my child ?

Jeff

推荐答案

如果要为子控件设置依赖项属性的默认值，则可以在.

If you want to set the default value of a dependency-property to a child control, you can set it in the constructor of the UserControl.

但是，为什么不使用绑定?

But, why don''t you use binding?

您可以设置子级Border的Background属性，如下所示:

You can set the Background property of the child Border, like the following:

<UserControl x:Class="DesktopApp.UserControls.Splitter"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <Border x:Name="oBorder"

            Background="{Binding SplitterColor, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}">
        <Border.Effect>
            <DropShadowEffect x:Name="oShadow" />
        </Border.Effect>
    </Border>
</UserControl>

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