Question

我有一个包含DependencyProperty（MyProperty）的WPF UserControl。

DependencyProperty绑定到DataContext中的Property。

现在在UserControl中我想更改bound属性的值。但是，如果我指定MyProperty = NewValue，则绑定将丢失并由NewValue替换。

我想要实现的是更改DependencyProperty绑定的DataContext属性。

如何实现这一目标而不是更改绑定？

澄清：使用像MyTextBox.Text = "0";这样的东西，我将释放绑定。我如何设置Text，保持绑定完整，因此绑定的属性也将改变。

Answer 1

您可以使用SetCurrentValue。

SetCurrentValue方法更改属性的有效值，但现有的触发器，数据绑定和样式将继续有效。

Answer 2

如果没有看到你的代码，我无法分辨你做错了什么。下面是一个简单的用户控件，允许用户选择颜色。

<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;
            }
        }
    }
}

Answer 3

这应该按原样工作，唯一的问题是当文本框失去焦点时，文本框绑定的绑定源将被更新。这是默认行为。您可以通过在绑定中指定UpdateSourceTrigger=PropertyChanged来更改它。像这样：

<TextBox Name="MyTextBox" Text="{Binding YourBindingPath, UpdateSourceTrigger=PropertyChanged}"/>

更改绑定值，而不是绑定自身

3 个答案: