C# wpf实现任意控件更多拖动功能
作者：CodeOfCC
这篇文章主要为大家详细介绍了C# wpf如何实现任意控件（包括窗口）更多拖动功能,文中的示例代码讲解详细,有兴趣的小伙伴可以跟随小编一起学习一下
前言
上一章我们已经实现了任意控件统一的拖动功能，以及能够方便的给任意控件添加拖动了。开发过程中发现还是有些功能可以继续拓展的，比如cs代码中移动控件、响应事件后触发拖动、限制拖动范围等功能。
一、添加的功能
在第五章基础上添加了如下功能。
1、任意控件MoveTo
这个功能相对简单，对不同类型的容器进行判断区分不同的移动逻辑即可。
代码示例如下：
/// <summary>
/// 任意控件移动到指定坐标点
/// </summary>
/// <param name="elememt">this</param>
/// <param name="parentPoint">父容器的坐标点，之所以采样容器的坐标是因为，采样自身坐标控件位置改变后就会无效，采样屏幕坐标则需要自己换算dpi（PointToScreen不会做dpi换算）</param>
public static void MoveTo(this FrameworkElement elememt, Point parentPoint)
{
var parent = VisualTreeHelper.GetParent(elememt);
if (parent is Canvas)
{
//Canvas移动逻辑
}
else if (elememt is Window)
{
//Window移动逻辑
}
else
{
//Grid或Transform移动逻辑，两种都能适用任意控件
}
}
在拓展一个获取位置的方法，方便MoveTo使用
/// <summary>
/// 获取控件坐标，基于父控件。Window则是桌面位置。
/// </summary>
/// <param name="elememt"></param>
public static Point GetPosition(this FrameworkElement elememt)
{
var parent = VisualTreeHelper.GetParent(elememt);
if (elememt is Window)
{
var window = elememt as Window;
return new Point(window!.Left, window.Top);
}
return elememt.TranslatePoint(new Point(0, 0), parent as UIElement);
}
2、任意控件DragMove
我们知道wpf的Window有DragMove功能，在鼠标左键按下事件中调用此方法就能实现拖动功能很方便。任意控件的DragMove也是可以实现的，我们需要使用第五章的DragMoveable对象结合手动触发事件来实现。
代码示例如下：
/// <summary>
/// 点击拖动
/// 与Window的DragMove类似，必须鼠标左键按下调用此方法。
/// await 可以等待拖动结束
/// </summary>
/// <param name="elememt">this</param>
/// <returns></returns>
/// <exception cref="InvalidOperationException"></exception>
public static Task DragMove(this FrameworkElement elememt)
{
if (Mouse.LeftButton != MouseButtonState.Pressed)
{
throw new InvalidOperationException("Left button down to call this method");
}
var tcs = new TaskCompletionSource();
//初始化DragMoveable对象
//手动触发elememt的鼠标左键按下事件
//拖动完成后tcs.SetResult();
return tcs.Task;
}
3、边界限制
添加一个IsMoveInBounds附加属性，表示拖动范围是否在父控件内。
代码示例如下：
public static bool GetIsMoveInBounds(DependencyObject obj)
{
return (bool)obj.GetValue(IsMoveInBoundsProperty);
}
public static void SetIsMoveInBounds(DependencyObject obj, bool value)
{
obj.SetValue(IsMoveInBoundsProperty, value);
}
/// <summary>
/// 是否在父容器区域内拖动，不会超出边界
/// </summary>
// Using a DependencyProperty as the backing store for IsMoveInBounds. This enables animation, styling, binding, etc...
public static readonly DependencyProperty IsMoveInBoundsProperty =
DependencyProperty.RegisterAttached("IsMoveInBounds", typeof(bool), typeof(Move), new PropertyMetadata(true));
在第五章 附加属性实现任意拖动的拖动逻辑中添加相应的限制功能，比如Canvas的示例如下:
var p = _parent as Canvas;
if (GetIsMoveInBounds(c))
//修正移动范围
{
if (left < 0) left = 0;
if (top < 0) top = 0;
if (left + c.ActualWidth > p.ActualWidth) left = p.ActualWidth - c.ActualWidth;
if (top + c.ActualHeight > p.ActualHeight) top = p.ActualHeight - c.ActualHeight;
}
4、窗口最大化拖动还原
Windows系统的窗口最大化拖动标题时会自动恢复为普通状态的窗口，实现无边框窗口后则失去了这个功能，需要自己实现，而且恢复普通状态的窗口的位置还有一定的逻辑。
代码示例如下：
if (window.WindowState == WindowState.Maximized)
//最大化时拖动逻辑
{
//恢复为普通窗口
window.WindowState = WindowState.Normal;
double width = SystemParameters.PrimaryScreenWidth;//得到屏幕整体宽度
double height = SystemParameters.PrimaryScreenHeight;//得到屏幕整体高度
//根据鼠标的位置调整窗口位置，基本逻辑是横向为鼠标为中点，纵向为鼠标顶部,超出屏幕范围则修正到靠近的那一边。
}
5、拖动事件
提供3个拖动事件，拖动结束、拖动变化、拖动结束。
代码示例如下：
/// <summary>
/// 拖动开始事件
/// </summary>
public static readonly RoutedEvent DragMoveStartedEvent = EventManager.RegisterRoutedEvent("DragMoveStarted", RoutingStrategy.Direct, typeof(EventHandler<DragMoveStartedEventArgs>), typeof(Move));
/// <summary>
/// 拖动变化事件
/// </summary>
public static readonly RoutedEvent DragMoveDeltaEvent = EventManager.RegisterRoutedEvent("DragMoveDelta", RoutingStrategy.Direct, typeof(EventHandler<DragMoveDeltaEventArgs>), typeof(Move));
/// <summary>
/// 拖动结束事件
/// </summary>
public static readonly RoutedEvent DragMoveCompletedEvent = EventManager.RegisterRoutedEvent("DragMoveCompleted", RoutingStrategy.Direct, typeof(EventHandler<DragMoveCompletedEventArgs>), typeof(Move));
二、使用示例
由于本章是第五章的拓展，基本功能可以参考第五章。
1、MoveTo
xaml
<Window x:Class="WpfMove.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:WpfMove"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
>
<Grid>
<Button Width="180" Height="30" Click="Button_Click">Gird中点击按钮右移10</Button>
<StackPanel>
<Button Width="180" Height="30" Click="Button_Click">StackPanel中点击按钮右移10</Button>
</StackPanel>
<Canvas>
<Button Width="180" Height="30" Click="Button_Click">Canvas中点击按钮右移10</Button>
</Canvas>
</Grid>
</Window>
因为是拓展方法，所以获取到控件对象直接调用moveTo即可。
cs
using AC;
using System.Windows;
using System.Windows.Media;
namespace WpfMove
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var fe = sender as FrameworkElement;
//获取控件的位置
var p = fe.GetPosition();
//右偏移10
p.Offset(10, 0);
fe.MoveTo(p);
}
}
}
效果预览
2、DragMove
xaml
<Window x:Class="WpfMove.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:WpfMove"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
>
<Grid>
<TextBlock Background="Aqua" TextAlignment="Center" Margin="0,80,0,0" Width="180" Height="30" MouseDown="TextBlock_MouseDown" >Gird中点击拖动</TextBlock>
<StackPanel>
<TextBlock Background="Aqua" TextAlignment="Center" Margin="0,80,0,0" Width="180" Height="30" MouseDown="TextBlock_MouseDown" >StackPanel中点击拖动</TextBlock>
</StackPanel>
<Canvas >
<TextBlock Background="Aqua" TextAlignment="Center" Margin="0,80,0,0" Width="180" Height="30" MouseDown="TextBlock_MouseDown" >Canvas中点击拖动</TextBlock>
</Canvas>
</Grid>
</Window>
此方法也是拓展方法，在鼠标按下事件中任意控件都可以调用此方法，可以通过await等待拖动完成。
cs
using AC;
using System;
using System.Windows;
namespace WpfMove
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private async void TextBlock_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
var fe = sender as FrameworkElement;
await fe.DragMove();
Console.WriteLine("拖动完成");
}
}
}
效果预览
3、边界限制
通过附加属性IsMoveInBounds设置是否限制边界，默认为false。
xaml
<Window x:Class="WpfMove.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:WpfMove"
xmlns:ac="clr-namespace:AC"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
>
<Grid>
<TextBlock HorizontalAlignment="Left" Background="Aqua" TextAlignment="Center" Margin="0,80,0,0" Width="180" Height="60" ac:Move.IsDragMoveable="True" ac:Move.IsMoveInBounds="True">拖动限制边界</TextBlock>
<TextBlock HorizontalAlignment="Right" Background="Aqua" TextAlignment="Center" Margin="0,80,0,0" Width="180" Height="60" ac:Move.IsDragMoveable="True" ac:Move.IsMoveInBounds="False">拖动不限制边界</TextBlock>
</Grid>
</Window>
效果预览
4、窗口最大化拖动还原
内部实现已支持最大化拖动还原，只需要设置窗口可拖动即可，使用场景是无边框窗口自定义标题栏。
xaml
<Window x:Class="WpfMove.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:WpfMove"
xmlns:ac="clr-namespace:AC"
mc:Ignorable="d"
WindowStyle="None"
ResizeMode="NoResize"
WindowState="Normal"
Title="MainWindow" Height="450" Width="800"
x:Name="window"
>
<Grid>
<Border VerticalAlignment="Top" Height="40" Background="#333333" ac:Move.DragMoveTarget="{Binding ElementName= window}" MouseLeftButtonDown="Border_MouseLeftButtonDown">
<TextBlock Margin="0,0,10,0" VerticalAlignment="Center" HorizontalAlignment="Right" Foreground="White" Text="标题栏拖动窗口"></TextBlock>
</Border>
</Grid>
</Window>
cs
using System.Windows;
namespace WpfMove
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Border_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if (e.ClickCount == 2) WindowState = WindowState != WindowState.Maximized ? WindowState = WindowState.Maximized : WindowState = WindowState.Normal;
}
}
}
效果预览
5、拖动事件
xaml
<Window x:Class="WpfMove.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:WpfMove"
xmlns:ac="clr-namespace:AC"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
>
<StackPanel>
<TextBlock Background="Aqua"
TextAlignment="Center"
Margin="0,80,0,0" Width="180" Height="30"
ac:Move.IsDragMoveable="True"
ac:Move.DragMoveStarted="window_DragMoveStarted"
ac:Move.DragMoveCompleted="window_DragMoveCompleted"
ac:Move.DragMoveDelta="window_DragMoveDelta">StackPanel中点击拖动</TextBlock>
</StackPanel>
</Window>
cs
using AC;
using System;
using System.Windows;
namespace WpfMove
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void window_DragMoveStarted(object sender, DragMoveStartedEventArgs e)
{
Console.WriteLine("拖动开始");
}
private void window_DragMoveCompleted(object sender, DragMoveCompletedEventArgs e)
{
Console.WriteLine("拖动完成");
}
private void window_DragMoveDelta(object sender, DragMoveDeltaEventArgs e)
{
Console.WriteLine("横向偏移："+e.HorizontalOffset + "," +"纵向偏移："+ e.VerticalOffset);
}
}
}效果预览
总结
拓展更多的拖动功能后使用变得更加方便了，灵活度也提高了。使用xmal或cs代码都能实现拖动，实现自定义标题栏也变得很简单，有了拖动事件也可以做一些撤销重做的功能。总的来说，本文的拖动功能一定程度可以作为通用的模块在项目中使用了。
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