好吧,这是WPF的明确新手,显然需要不断学习MVVM,我的代码并没有专门设计,但是我确实指定了一个类作为GUI的接口和控制器,而模型代码驻留在另一组类中。一直在搜索网络上的例子,以及类似我的问题,其中有很多,但经过迷宫三天后,我正在寻求帮助。
我需要的是一个简单的下拉菜单,其中包含可以动态更新的项目(它是一个与USB设备通信的应用程序,因此有许多可用的设备应显示其设备ID和序列号),以及当前选中的项目应该显示在Button上(或者我最终得到的Dropdown菜单的任何实现)。在这个例子中,我只是创建一个静态列表,但稍后将在完整的应用程序中动态更新相同的列表。
到目前为止,我看到它在正确的轨道上:我得到当前选定的设备ID字符串以显示在按钮上,按下按钮,我得到所有可用设备的列表(它没有'打扰我当前选择的设备在列表中冗余显示。但是,当选择一个项目时,我无法挂钩任何事件,因此无法更新按钮中的项目,或者做任何其他事情。
我的XAML如下。请注意,这大致被黑客攻击,并且这里有一些没有意义的东西,例如来自示例的“IsChecked”属性的“IsActive”。最大的问题是,就我所知,ContextMenu.Resources中的Setter属性似乎都没有做任何事情......尝试更改fontsize无济于事。当然,真正重要的问题是“MyCommand”绑定无效,该方法永远不会被调用。
<Label Content="Device Selected:" HorizontalAlignment="Left" Margin="25,22,0,0" VerticalAlignment="Top" Width="124" FontWeight="Bold" FontSize="14" Height="25"/>
<Button x:Name="DeviceSelMenuButton" Content="{Binding DeviceID_and_SN, Mode=TwoWay}" HorizontalAlignment="Left" Height="28" Margin="25,52,0,0" VerticalAlignment="Top" Width="187" FontSize="14" Click="DeviceSelMenuButton_Click">
<Button.ContextMenu>
<ContextMenu ItemsSource="{Binding DeviceID_SN_Collection, Mode=TwoWay}">
<ContextMenu.Resources>
<Style x:Key="SelectDeviceStyle" TargetType="MenuItem">
<Setter Property="Command" Value="{Binding MyCommand}"/>
<Setter Property="CommandTarget" Value="{Binding RelativeSource Self}"/>
<Setter Property="IsChecked" Value="{Binding IsActive}"/>
<Setter Property="IsCheckable" Value="True"/>
<Setter Property="FontSize" Value="14"/>
</Style>
</ContextMenu.Resources>
</ContextMenu>
</Button.ContextMenu>
</Button>
来自MainWindow.xaml.cs的代码:
public partial class MainWindow : Window
{
CustomDeviceGUI _customDeviceGui = new CustomDeviceGUI();
public MainWindow()
{
InitializeComponent();
this.DataContext = _customDeviceGui;
}
private void DeviceSelMenuButton_Click(object sender, RoutedEventArgs e)
{
// " (sender as Button)" is PlacementTarget
(sender as Button).ContextMenu.IsEnabled = true;
(sender as Button).ContextMenu.PlacementTarget = (sender as Button);
(sender as Button).ContextMenu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
(sender as Button).ContextMenu.IsOpen = true;
}
private void SomeMethod(object sender, DataTransferEventArgs e)
{
// TODO Somehow get the index of the selected menu item (collection index, 0-based)
// int selIndex = (sender as Button).ContextMenu.Items.IndexOf ??
_customDeviceGui.UpdateDeviceID("RelayPro id updated");
}
}
GUI代码:
class CustomDeviceGUI : INotifyPropertyChanged
{
// Declare the event
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private string _deviceDisplayString;
private ICommand _updateMenu;
List<string> ControllerDeviceList = new List<string>();
private System.Collections.ObjectModel.ObservableCollection<string> _DeviceID_SN_Collection = new System.Collections.ObjectModel.ObservableCollection<string>();
// CTOR
public CustomDeviceGUI()
{
ControllerDeviceList.Add("CustomDevice Device 1");
ControllerDeviceList.Add("CustomDevice Device 2");
ControllerDeviceList.Add("CustomDevice Device 3");
ControllerDeviceList.Add("CustomDevice Device 6");
UpdateDeviceID(ControllerDeviceList[0]);
}
#region CustomDeviceGUI Properties
public System.Collections.ObjectModel.ObservableCollection<string> DeviceID_SN_Collection
{
get
{
_DeviceID_SN_Collection.Clear();
foreach (string str in ControllerDeviceList)
{
_DeviceID_SN_Collection.Add(str);
}
return _DeviceID_SN_Collection;
}
private set
{
_DeviceID_SN_Collection = value;
}
}
public string DeviceID_and_SN
{
get
{
return _deviceDisplayString;
}
private set
{
_deviceDisplayString = value;
}
}
public ICommand MyCommand
{
get
{
if (_updateMenu == null)
_updateMenu = new MyGuiCommand();
return _updateMenu;
}
}
#endregion
#region Public Methods
public void UpdateDeviceID(string deviceID)
{
this._deviceDisplayString = deviceID;
RaisePropertyChangeEvent("DeviceID_and_SN");
RaisePropertyChangeEvent("DeviceID_SN_Collection");
}
#endregion
protected void RaisePropertyChangeEvent(string name)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
try
{
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
catch (Exception e)
{
// ... TODO Remove this catchall or find specific exceptions
}
}
public class MyGuiCommand : ICommand
{
public void Execute(object parameter)
{
// Debug.WriteLine("Hello, world");
int hmm = 3;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged // was ;
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
}
} // class CustomDeviceGUI
答案 0 :(得分:0)
我必须做的所有更改都在XAML中。主要是使用祖先来获取正确的数据上下文。我也切换到ContextMenu.ItemContainer而不是ContextMenu.Resources。
<ContextMenu.ItemContainerStyle>
<Style TargetType="MenuItem">
<Setter Property="Command" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}, Path=DataContext.MyCommand}"/>
</Style>
</ContextMenu.ItemContainerStyle>
答案 1 :(得分:-1)
尽管我不确定我是否认为:
<Setter Property="Command" Value="{Binding MyCommand}"/>
绑定需要一个RoutedUICommand对象。
编辑: 我注意到的另一件事是你之前没有设置任何命令绑定。像这样:
<Window.CommandBindings>
<CommandBinding Command="MyCommand" Executed="Execute" />
</Window.CommandBindings>
只是一个示例,您可以将CommandBindings设置为许多其他控件。