更改绑定值，而不是本身的结合 [英] Change binding value, not binding itself

问题描述

我有含的DependencyProperty（myProperty的）。一个WPF用户控件

I've got a WPF UserControl containing a DependencyProperty (MyProperty).

将DependencyProperty绑定到DataContext的一个属性。

The DependencyProperty is bound to a Property in the DataContext.

现在在该用户我想改变绑定属性的值。但是，如果我给 = myProperty的的NewValue 绑定被丢失的NewValue和更换。

Now in the UserControl I want to change the value of the bound property. But if I assign MyProperty = NewValue the Binding is lost and replaced by NewValue.

我想实现的就是改变的DataContext属性将DependencyProperty势必。

What I want to achieve is change the DataContext-property the DependencyProperty is bound to.

我如何做到这一点，而不是改变约束力？

How do I achieve this instead of changing the binding?

要澄清：使用类似 MyTextBox.Text =0; 我要解除绑定。我将如何设置文本，保留完好的结合使该属性的文本，势必会改变了。

To clarify: using something like MyTextBox.Text = "0"; I'll release the binding. How would I set Text, leave the binding intact so the property Text is bound to will change, too.

推荐答案

我不能告诉你，没有看到你的code做错了什么。下面是一个简单的用户控件，它允许用户选择一种颜色。

I can't tell what you are doing wrong without seeing your code. Below is a simple usercontrol that allows users to pick a color.

<UserControl x:Class="ColorPickerTest.ColorPicker"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <StackPanel Orientation="Horizontal">
        <ToggleButton Name="redButton" Content="Red" Click="Button_Click" />
        <ToggleButton Name="yellowButton" Content="Yellow" Click="Button_Click" />
    </StackPanel>
</UserControl>

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace ColorPickerTest
{
    public partial class ColorPicker : UserControl
    {
        public ColorPicker()
        {
            InitializeComponent();
        }

        public Brush SelectedColor
        {
            get { return (Brush)GetValue(SelectedColorProperty); }
            set { SetValue(SelectedColorProperty, value); }
        }

        public static readonly DependencyProperty SelectedColorProperty =
            DependencyProperty.Register("SelectedColor", 
                                        typeof(Brush), 
                                        typeof(ColorPicker), 
                                        new UIPropertyMetadata(Brushes.Transparent, OnPropertyChanged));

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            if (!redButton.IsChecked.GetValueOrDefault() && !yellowButton.IsChecked.GetValueOrDefault())
            {
                SelectedColor = Brushes.Transparent;
            }
            else if (!redButton.IsChecked.GetValueOrDefault() && yellowButton.IsChecked.GetValueOrDefault())
            {
                SelectedColor = Brushes.Yellow;
            }
            else if (redButton.IsChecked.GetValueOrDefault() && !yellowButton.IsChecked.GetValueOrDefault())
            {
                SelectedColor = Brushes.Red;
            }
            else
            {
                // redButton.IsChecked.GetValueOrDefault() && yellowButton.IsChecked.GetValueOrDefault())

                SelectedColor = Brushes.Orange;
            }
        }

        private static void OnPropertyChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            ColorPicker colorPicker = sender as ColorPicker;
            colorPicker.redButton.IsChecked = colorPicker.SelectedColor == Brushes.Red ||
                                              colorPicker.SelectedColor == Brushes.Orange;
            colorPicker.yellowButton.IsChecked = colorPicker.SelectedColor == Brushes.Yellow ||
                                                 colorPicker.SelectedColor == Brushes.Orange;
        }
    }
}

<Window x:Class="ColorPickerTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:ColorPickerTest="clr-namespace:ColorPickerTest"
    Height="300" Width="300">
    <StackPanel>
        <ColorPickerTest:ColorPicker SelectedColor="{Binding Path=MyColor, Mode=TwoWay}" />
    </StackPanel>
</Window>

using System.Windows;
using System.Windows.Media;

namespace ColorPickerTest
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            MyColor = Brushes.Red;

            DataContext = this;
        }

        private Brush _myColor;
        public Brush MyColor
        {
            get { return _myColor; }
            set 
            {
                _myColor = value;
                Background = _myColor;
            }
        }
    }
}

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