c# wpf 实现窗口任意区域点击拖动

系列文章目录

第一章 Grid内控件拖动
第二章 Canvas内控件拖动
第三章 任意控件拖动
第四章 窗口拖动（本章）
第五章 附加属性实现任意拖动

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前言

点击窗口任意区域可移动功能，在一些业务场景中会使用到，比如工具条或者球形状的窗口等。在wpf要实现此功能简单形式还是比较容易的，但是有一些细节需要专门处理，比如与按钮的点击事件冲突问题，解决事件冲突问题后拖动的灵敏度，可复用性等。

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一、简单拖动

基础的拖动功能直接使用Window类的DragMove即可实现：
在Window的PreviewMouseLeftButtonDown中调用DragMove即可。
示例如下：

<Window PreviewMouseLeftButtonDown="Window_PreviewMouseLeftButtonDown" />

void Window_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    DragMove();
}

注：本文实现的是窗口任意区域拖动（比如按钮占满整个窗口），不适用于一般窗口拖动，一般窗口拖动请使用MouseLeftButtonDown事件

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二、事件冲突问题

根据上述方法实现窗口拖动后发现出现了事件冲突，即窗口内的控件无法相应鼠标点击事件了。因为DragMove的内部实现使用了SC_MOVE，使标题栏（win32窗口）捕获鼠标，原本窗口失去鼠标捕获。窗口内的控件无法响应鼠标消息，因此上述简单拖动在有控件的窗口中是不可行的（局部拖动是可行的，但本文讲的是任意区域拖动）。

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三、解决方法

解决方法是不在鼠标按下事件中触发拖动，而是在鼠标移动后触发拖动操作。具体步骤如下：
1、注册3个事件如下：

<Window PreviewMouseLeftButtonDown="Window_PreviewMouseLeftButtonDown"
        PreviewMouseMove="Window_PreviewMouseMove"
        PreviewMouseLeftButtonUp="Window_PreviewMouseLeftButtonUp"/>

2、定义2个变量记录信息。

Point _pressedPosition ;
bool _isDragMoved = false;

3.记录鼠标按下位置

void Window_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    _pressedPosition = e.GetPosition(this);
}

4.鼠标移动触发拖动

 void Window_PreviewMouseMove(object sender, System.Windows.Input.MouseEventArgs e)
 {
     if (Mouse.LeftButton==MouseButtonState.Pressed && _pressedPosition != e.GetPosition(this))
     {
         _isDragMoved = true;
         DragMove();
     }
 }

5.鼠标弹起屏蔽消息

 void Window_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 {
     if (_isDragMoved)
     {
         _isDragMoved = false;
         e.Handled = true;
     }
 }

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四、效果预览

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五、使用示例

由于评论区反馈上述方法存在bug，但是无奈笔者始终没有重现，怀疑是使用方法不正确，或者对本博文讲述功能理解上的差异导致的，在此根据上述方法原封不动的编写如下使用示例，以说明使用场景以及使用方法。

1、白板的工具条

（1）、MainWindow.xaml

<Window x:Class="WpfApp3.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp3"
        mc:Ignorable="d"
        Background="Transparent"
        AllowsTransparency="True"
        WindowStyle="None"
        Title="MainWindow" Height="60" Width="410" 
        PreviewMouseLeftButtonDown="Window_PreviewMouseLeftButtonDown"
        PreviewMouseMove="Window_PreviewMouseMove"
        PreviewMouseLeftButtonUp="Window_PreviewMouseLeftButtonUp">
    <Border Background="White"  CornerRadius="25" Margin="5">
        <Border.Effect>
            <DropShadowEffect ShadowDepth="0" BlurRadius="5" Opacity="0.8" Color="#AAAAAA"/>
        Border.Effect>
        <StackPanel Margin="20,0,0,0" Orientation="Horizontal">
            <RadioButton     Content="画笔"  Width="50" Height="50" Cursor="Hand">
                <RadioButton.Template>
                    <ControlTemplate TargetType="RadioButton"  >
                        <Border Background="Transparent">
                            <TextBlock x:Name="txt"  Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="txt" Property="Foreground" Value="red">Setter>
                            Trigger>
                        ControlTemplate.Triggers>
                    ControlTemplate>
                RadioButton.Template>
            RadioButton>
            <RadioButton     Content="矩形"  Width="50" Height="50" Cursor="Hand">
                <RadioButton.Template>
                    <ControlTemplate TargetType="RadioButton"  >
                        <Border Background="Transparent">
                            <TextBlock x:Name="txt"  Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="txt" Property="Foreground" Value="red">Setter>
                            Trigger>
                        ControlTemplate.Triggers>
                    ControlTemplate>
                RadioButton.Template>
            RadioButton>
            <RadioButton     Content="文本"  Width="50" Height="50" Cursor="Hand">
                <RadioButton.Template>
                    <ControlTemplate TargetType="RadioButton"  >
                        <Border Background="Transparent">
                            <TextBlock x:Name="txt"  Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="txt" Property="Foreground" Value="red">Setter>
                            Trigger>
                        ControlTemplate.Triggers>
                    ControlTemplate>
                RadioButton.Template>
            RadioButton>
            <RadioButton     Content="箭头"  Width="50" Height="50" Cursor="Hand">
                <RadioButton.Template>
                    <ControlTemplate TargetType="RadioButton"  >
                        <Border Background="Transparent">
                            <TextBlock x:Name="txt"  Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="txt" Property="Foreground" Value="red">Setter>
                            Trigger>
                        ControlTemplate.Triggers>
                    ControlTemplate>
                RadioButton.Template>
            RadioButton>
            <RadioButton     Content="图片"  Width="50" Height="50" Cursor="Hand">
                <RadioButton.Template>
                    <ControlTemplate TargetType="RadioButton"  >
                        <Border Background="Transparent">
                            <TextBlock x:Name="txt"  Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="true">
                                <Setter TargetName="txt" Property="Foreground" Value="red">Setter>
                            Trigger>
                        ControlTemplate.Triggers>
                    ControlTemplate>
                RadioButton.Template>
            RadioButton>
            <Border Margin="10,0,0,0" BorderThickness="1,0,0,0" BorderBrush="#999999">Border>
            <Button  Name="btn_upload" Margin="0,0,0,0"   Content="上传"  Width="50" Height="50" Cursor="Hand" Click="btn_upload_Click">
                <Button.Template>
                    <ControlTemplate TargetType="Button"  >
                        <Border Background="Transparent">
                            <TextBlock Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                    ControlTemplate>
                Button.Template>
            Button>
            <Button  Name="btn_close" Margin="0,0,0,0"   Content="关闭"  Width="50" Height="50"  Cursor="Hand"  Click="btn_close_Click">
                <Button.Template>
                    <ControlTemplate TargetType="Button"  >
                        <Border Background="Transparent">
                            <TextBlock Background="Transparent"  TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#666666" FontSize="18"
                         Text="{TemplateBinding Content}">TextBlock>
                        Border>
                    ControlTemplate>
                Button.Template>
            Button>
        StackPanel>
    Border>
Window>

（2）、MainWindow.xaml.cs

using System.Windows;
using System.Windows.Input;
namespace WpfApp3
{
    /// 

    /// MainWindow.xaml 的交互逻辑
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        Point _pressedPosition;
        bool _isDragMoved = false;
        void Window_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            _pressedPosition = e.GetPosition(this);
        }
        void Window_PreviewMouseMove(object sender, System.Windows.Input.MouseEventArgs e)
        {
            if (Mouse.LeftButton == MouseButtonState.Pressed && _pressedPosition != e.GetPosition(this))
            {
                _isDragMoved = true;
                DragMove();
            }
        }
        void Window_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            if (_isDragMoved)
            {
                _isDragMoved = false;
                e.Handled = true;
            }
        }
        private void btn_upload_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("上传成功");
        }
        private void btn_close_Click(object sender, RoutedEventArgs e)
        {
            Close();
        }   
    }
}

（3）、效果预览

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总结

本文介绍了在窗口任意区域点击拖动的方法。简单的拖动是不可行的，往深一步探究，发现了巧妙的解决方法：在鼠标移动时触发拖动。但这也不是一蹴而就的，这是笔者曾经做项目经过了一定的探究最终得以实现，而本文呈现的是优化后的精简版本，易于实现也很好理解，即是所谓的大道至简。