我在Button内托管了UserControl我想在视图中保留属性的数值时更改Background和Foreground属性UserControl更改的模型。
我的视图模型显示如下（为简洁起见，删除了属性和方法）。我正在使用Prism的DelegateCommand<T>作为我的命令。
public class PianoKeyViewModel : BindingTarget, IPianoKey
{
private byte afterTouch;
private DelegateCommand<AfterTouchEventArgs> afterTouchChangedCommand;
public byte AfterTouch
{
get
{
return afterTouch;
}
set
{
//Calls a method on BindingTarget to assign to afterTouch and call RaisePropertyChanged.
SetProperty(ref afterTouch, value);
}
}
public DelegateCommand<AfterTouchEventArgs> AfterTouchChangedCommand
{
get
{
return afterTouchChangedCommand;
}
set
{
//Calls a method on BindingTarget to assign to afterTouchChangedCommand and call RaisePropertyChanged.
SetProperty(ref afterTouchChangedCommand, value);
}
}
protected override void RaisePropertyChanged([CallerMemberName]string propertyName = null)
{
base.RaisePropertyChanged(propertyName);
switch (propertyName)
{
case nameof(AfterTouch):
AfterTouchEventArgs afterTouchEventArgs = new AfterTouchEventArgs(AfterTouch);
if (AfterTouchChangedCommand != null && AfterTouchChangedCommand.CanExecute(afterTouchEventArgs))
//Executes the AfterTouchChangedCommand since the AfterTouchProperty has just changed and the command exists and can execute.
AfterTouchChangedCommand.Execute(afterTouchEventArgs);
break;
}
}
}
UserControl的XAML大幅缩减版本如下。请注意我的TODO注释下面的行 - AfterTouchChanged不存在，需要替换为绑定到AfterTouchChangedCommand，当调用Execute时触发触发器。此外，此DataContext的{{1}}将是上面显示的视图模型，这是通过使用Prism的模块实现的。
UserControl我需要更换<UserControl x:Class="MyNamespace.PianoKey.View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:converters="clr-namespace:MyNamespace.PianoKey.View.Converters"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
<converters:AfterTouchToBackgroundColorConverter x:Key="afterTouchToBackgroundColorConverter"/>
<converters:AfterTouchToForegroundColorConverter x:Key="afterTouchToForegroundColorConverter"/>
</UserControl.Resources>
<UserControl.Template>
<Button>
<Button.Triggers>
<!--TODO: Find out what trigger is needed here to respond to AfterTouchChangedCommand.Execute.-->
<EventTrigger RoutedEvent="AfterTouchChanged">
<Setter Property="Background" Value="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=AfterTouch, Converter={StaticResource afterTouchToBackgroundColorConverter}}"/>
<Setter Property="Foreground" Value="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=AfterTouch, Converter={StaticResource afterTouchToForegroundColorConverter}}"/>
</EventTrigger>
</Button.Triggers>
</Button>
</UserControl.Template>
</UserControl>
以获取更新EventTrigger的{{1}}和Background颜色？ Foreground看起来很有希望，但据我所知，这只能响应绑定源上属性的单个值。