扩展UserControl WPF的自定义控件中的TextChanged或ContentChanged事件(TextChanged or ContentChanged event in a custo

扩展UserControl WPF的自定义控件中的TextChanged或ContentChanged事件(TextChanged or ContentChanged event in a custom control extending UserControl WPF)

我在开源应用程序中有一个我想要更改的自定义控件。

XAML看起来像这样：

<controls:Scratchpad Grid.Row="1" Grid.Column="2" Text="{Binding DataContext.KeyboardOutputService.Text, RelativeSource={RelativeSource AncestorType=controls:KeyboardHost}, Mode=OneWay}"/>

Scratchpad控件的代码隐藏如下所示：

public class Scratchpad : UserControl { public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof (string), typeof (Scratchpad), new PropertyMetadata(default(string))); public string Text { get { return (string) GetValue(TextProperty); } set { SetValue(TextProperty, value); } } }

我想在每次UserControl中的文本更改时触发事件处理程序。 但是，我没有可以在XAML中使用的TextChanged事件。

我的计划是做这样的事情：

<controls:Scratchpad Grid.Row="1" Grid.Column="2" Text="{Binding DataContext.KeyboardOutputService.Text, RelativeSource={RelativeSource AncestorType=controls:KeyboardHost}, Mode=OneWay}" textChanged="EventHandler"/>

但是，此自定义控件中不存在“textChanged”事件。

如您所见，ScratchPad扩展了UserControl。 UserControl还扩展了ContentControl，这就是为什么我认为可以将文本放在这个控件中，它们可能是我不知道的“ContentChanged”事件。

最好，彼得。

I have a custom control in an open source application that I want to change.

The XAML looks like this:

<controls:Scratchpad Grid.Row="1" Grid.Column="2" Text="{Binding DataContext.KeyboardOutputService.Text, RelativeSource={RelativeSource AncestorType=controls:KeyboardHost}, Mode=OneWay}"/>

The codebehind for the Scratchpad control looks like this:

public class Scratchpad : UserControl { public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof (string), typeof (Scratchpad), new PropertyMetadata(default(string))); public string Text { get { return (string) GetValue(TextProperty); } set { SetValue(TextProperty, value); } } }

I want to trigger an event handler each time the text changes in the UserControl. However there is no TextChanged event that I can use in the XAML.

My plan was to do something like this:

<controls:Scratchpad Grid.Row="1" Grid.Column="2" Text="{Binding DataContext.KeyboardOutputService.Text, RelativeSource={RelativeSource AncestorType=controls:KeyboardHost}, Mode=OneWay}" textChanged="EventHandler"/>

However the "textChanged" event does not exist in this custom control.

As you can see, ScratchPad extends UserControl. UserControl also extends ContentControl, and that's why I think it is possible to put text in this control, their might be a "ContentChanged" event that I don't know about.

Best, Peter.

最满意答案

两种选择：

（MVVM方式）如果更改是为了反映域模型中的某些内容，则此更改可能最适合在viewmodel中处理

（控制方式）您是否考虑过在DependencyProperty中添加更改的处理程序？

public static readonly DependencyProperty TextProperty = DependencyProperty.Register(nameof(Text), typeof(string), typeof(ScratchPad), new PropertyMetadata(null, OnTextChanged)); private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { // Handle change here }

Two options:

(MVVM way) If the change is to reflect something in the domain model, perhaps this change is best suited for handling in your viewmodel

(Control way) Have you considered putting a changed handler in your DependencyProperty?

public static readonly DependencyProperty TextProperty = DependencyProperty.Register(nameof(Text), typeof(string), typeof(ScratchPad), new PropertyMetadata(null, OnTextChanged)); private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { // Handle change here }