我有一个 WPF 应用程序..我在 Xaml 文件中有一个图像控件。
右键单击此图像我有一个上下文菜单。
我也想在“左键单击”上显示相同的内容。
如何以 MVVM 方式执行此操作？
这是一个仅限 XAML 的解决方案。 只需将此样式添加到您的按钮即可。 这将导致上下文菜单在左键单击和右键单击时打开。享受吧！
<Button Content="Open Context Menu">
<Button.Style>
<Style TargetType="{x:Type Button}">
<Style.Triggers>
<EventTrigger RoutedEvent="Click">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard>
<BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="ContextMenu.IsOpen">
<DiscreteBooleanKeyFrame KeyTime="0:0:0" Value="True"/>
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</Style.Triggers>
<Setter Property="ContextMenu">
<Setter.Value>
<ContextMenu>
<MenuItem />
<MenuItem />
</ContextMenu>
</Setter.Value>
</Setter>
</Style>
</Button.Style>
</Button>
你可以通过像这样使用图像的 MouseDown 事件来做到这一点
<Image ... MouseDown="Image_MouseDown">
<Image.ContextMenu>
<ContextMenu>
<MenuItem .../>
<MenuItem .../>
</ContextMenu>
</Image.ContextMenu>
</Image>
然后在后面的代码中显示 EventHandler 中的 ContextMenu
private void Image_MouseDown(object sender, MouseButtonEventArgs e)
{
if (e.ChangedButton == MouseButton.Left)
{
Image image = sender as Image;
ContextMenu contextMenu = image.ContextMenu;
contextMenu.PlacementTarget = image;
contextMenu.IsOpen = true;
e.Handled = true;
}
}
您可以发明自己的 DependencyProperty，它会在单击图像时打开上下文菜单，就像这样：
<Image Source="..." local:ClickOpensContextMenuBehavior.Enabled="True">
<Image.ContextMenu>...
</Image.ContextMenu>
</Image>
这是该属性的 C# 代码：
public class ClickOpensContextMenuBehavior
{
private static readonly DependencyProperty ClickOpensContextMenuProperty =
DependencyProperty.RegisterAttached(
"Enabled", typeof(bool), typeof(ClickOpensContextMenuBehavior),
new PropertyMetadata(new PropertyChangedCallback(HandlePropertyChanged))
);
public static bool GetEnabled(DependencyObject obj)
{
return (bool)obj.GetValue(ClickOpensContextMenuProperty);
}
public static void SetEnabled(DependencyObject obj, bool value)
{
obj.SetValue(ClickOpensContextMenuProperty, value);
}
private static void HandlePropertyChanged(
DependencyObject obj, DependencyPropertyChangedEventArgs args)
{
if (obj is Image) {
var image = obj as Image;
image.MouseLeftButtonDown -= ExecuteMouseDown;
image.MouseLeftButtonDown += ExecuteMouseDown;
}
if (obj is Hyperlink) {
var hyperlink = obj as Hyperlink;
hyperlink.Click -= ExecuteClick;
hyperlink.Click += ExecuteClick;
}
}
private static void ExecuteMouseDown(object sender, MouseEventArgs args)
{
DependencyObject obj = sender as DependencyObject;
bool enabled = (bool)obj.GetValue(ClickOpensContextMenuProperty);
if (enabled) {
if (sender is Image) {
var image = (Image)sender;
if (image.ContextMenu != null)
image.ContextMenu.IsOpen = true;
}
}
}
private static void ExecuteClick(object sender, RoutedEventArgs args)
{
DependencyObject obj = sender as DependencyObject;
bool enabled = (bool)obj.GetValue(ClickOpensContextMenuProperty);
if (enabled) {
if (sender is Hyperlink) {
var hyperlink = (Hyperlink)sender;
if(hyperlink.ContextMenu != null)
hyperlink.ContextMenu.IsOpen = true;
}
}
}
}
如果您想只在 Xaml 中执行此操作而不使用代码隐藏，您可以使用 Expression Blend 的触发器支持：
...
xmlns:i="schemas.microsoft.com/expression/2010/interactivity"
...
<Button x:Name="addButton">
<Button.ContextMenu>
<ContextMenu ItemsSource="{Binding Items}" />
<i:Interaction.Triggers>
<i:EventTrigger EventName="Click">
<ei:ChangePropertyAction TargetObject="{Binding ContextMenu, ElementName=addButton}" PropertyName="PlacementTarget" Value="{Binding ElementName=addButton, Mode=OneWay}"/>
<ei:ChangePropertyAction TargetObject="{Binding ContextMenu, ElementName=addButton}" PropertyName="IsOpen" Value="True"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</Button.ContextMenu>
</Button>
你只需要将代码添加到函数 Image_MouseDown
e.Handled = true;
那就不会消失了
嘿，我遇到了同样的问题，正在寻找我在这里找不到的解决方案。
我对 MVVM 一无所知，所以它可能不符合 MVVM 但它对我有用。
第 1 步：为上下文菜单命名。
<Button.ContextMenu>
<ContextMenu Name="cmTabs"/>
</Button.ContextMenu>
第2步：双击控件对象并插入此代码。订单很重要！
Private Sub Button_Click_1(sender As Object, e As Windows.RoutedEventArgs)
cmTabs.StaysOpen = True
cmTabs.IsOpen = True
End Sub
第三步：享受
这将对左键和右键单击做出反应。这是一个带有 ImageBrush 和 ControlTemplate 的按钮。
您可以将 contextMenu 的 Isopen 属性绑定到 viewModel 中的属性，例如“IsContextMenuOpen”。 但问题是您不能将上下文菜单直接绑定到您的 viewModel，因为它不是您的 userControl 层次结构的一部分。因此，要解决此问题，您应该将标签属性绑定到视图的 dataontext。
<Image Tag="{Binding DataContext, ElementName=YourUserControlName}">
<ContextMenu IsOpen="{Binding PlacementTarget.Tag.IsContextMenuOpen,Mode=OneWay}" >
.....
</ContextMenu>
<Image>
祝你好运。
Interactivity 是旧的，不再支持了。新的实施方法是：
xmlns:b="http://schemas.microsoft.com/xaml/behaviors"
<Button x:Name="ConvertVideoButton">
<Button.ContextMenu>
<ContextMenu VerticalContentAlignment="Top" >
<MenuItem Header="Convert 1" Command="{Binding ConvertMkvCommand}" />
<MenuItem Header="Convert 2" Command="{Binding ConvertMkvCommand}" />
</ContextMenu>
</Button.ContextMenu>
<b:Interaction.Triggers>
<b:EventTrigger EventName="Click">
<b:ChangePropertyAction TargetObject="{Binding ContextMenu, ElementName=ConvertVideoButton}" PropertyName="PlacementTarget" Value="{Binding ElementName=ConvertVideoButton, Mode=OneWay}"/>
<b:ChangePropertyAction TargetObject="{Binding ContextMenu, ElementName=ConvertVideoButton}" PropertyName="IsOpen" Value="True"/>
</b:EventTrigger>
</b:Interaction.Triggers>
</Button>
XAML
<Button x:Name="b" Content="button" Click="b_Click" >
<Button.ContextMenu >
<ContextMenu >
<MenuItem Header="Open" Command="{Binding OnOpen}" ></MenuItem>
<MenuItem Header="Close" Command="{Binding OnClose}"></MenuItem>
</ContextMenu>
</Button.ContextMenu>
</Button>
C#
private void be_Click(object sender, RoutedEventArgs e)
{
b.ContextMenu.DataContext = b.DataContext;
b.ContextMenu.IsOpen = true;
}