单击按钮时打开 WPF 弹出窗口

Posted 2023-02-22

【中文标题】单击按钮时打开 WPF 弹出窗口

【英文标题】：Opening a WPF popup on button click

【发布时间】：2018-12-18 01:47:50

【问题描述】：

我有一个 WPF 按钮，当单击按钮时，我试图在其上方或顶部显示一个 WPF 弹出窗口：

<StackPanel Grid.Column="3">
    <Button x:Name="btnPrint"
        FocusVisualStyle="x:Null" 
        Style="DynamicResource MyButtonStyle"  
        Margin="15 5 5 5" Height="29"
        IsEnabled="Binding BtnPrintEnabled" 
        Command="Binding btnPrintCommand" 
        IsTabStop="False">
        Print
    </Button>
    <Popup IsOpen="Binding IsPrintPopupOpen" StaysOpen="False"  >
        <Border Background="LightYellow">
            <TextBlock>Sending to print ...</TextBlock>
        </Border>
    </Popup>
</StackPanel>

Popup 绑定到视图模型中的属性，因此当单击按钮时，会执行按钮命令。命令在视图模型中执行以下方法：

private void ImprimirRemesa()

   IsPrintPopupOpen = true;

   // Do some things

   IsPrintPopupOpen = false;


private bool _isPrintPopupOpen = false;
public bool IsPrintPopupOpen

    get
    
        return _isPrintPopupOpen;
    

    set
    
        if (_isPrintPopupOpen = value) return;

        _isPrintPopupOpen = value;
        OnPropertyChanged("IsPrintPopupOpen");
    

但它不起作用。什么都没有发生。

【问题讨论】：

if(_isPrintPopupOpen == value) 你是缺少 '=' 还是只是一个错字

如何更改 IsPrintPopupOpen 的值？

没有调用ImprimirRemesa() 方法中的“没有任何反应”，或者没有显示弹出窗口中的“没有任何反应”？

@tabby 是的，你是对的。这就是问题所在。

@Babbillumpa 如代码所示，我做了一个赋值，IsPrintPopupOpen = true。

【参考方案1】：

创建一个新的 wpf 项目。

也添加一个 nuget 引用 https://www.nuget.org/packages/RelayCommand 以利用 RelayCommand。

MainWindow.xaml.cs

using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Documents.DocumentStructures;
using System.Windows.Input;
using ButtonPopup.View.ViewModel;

namespace ButtonPopup

    /// <summary>
    ///     Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    
        public MainWindow()
        
            InitializeComponent();

            DataContext = new DataContextObject();
        
    

    public class DataContextObject : INotifyPropertyChanged
    
        private bool _isPrintPopupOpen;

        public bool IsPrintPopupOpen
        
            get  return _isPrintPopupOpen; 

            set
            
                if (_isPrintPopupOpen == value)
                
                    return;
                

                _isPrintPopupOpen = value;
                OnPropertyChanged(nameof(IsPrintPopupOpen));
            
        

        public ICommand PrintCommand => new RelayCommand(InitiatePrint);

        private async void InitiatePrint(object obj)
        
            IsPrintPopupOpen = true;

            await Task.Delay(3000);

            IsPrintPopupOpen = false;
        

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        
    

MainWindow.xaml：

<Grid>
    <Button x:Name="btnPrint"
            Margin="15 5 5 5" Height="29"
            Command="Binding PrintCommand" 
            IsTabStop="False">
        Print
    </Button>
    <Popup IsOpen="Binding IsPrintPopupOpen" StaysOpen="False" PlacementTarget="Binding ElementName=btnPrint" >
        <Border Background="LightYellow">
            <TextBlock>Sending to print ...</TextBlock>
        </Border>
    </Popup>
</Grid>

视觉表现：

【讨论】：

非常好的例子！