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Silverlight 拖动复制控件

作者: forgetu  来源: 博客园  发布时间: 2010-09-05 13:20  阅读: 2912 次  推荐: 0   原文链接   [收藏]  

  Silverlight 拖动复制控件,就是将控件从一个容器中向另一个容器中拖动时,不是移动控件而把该控件到另一个容器中。这种情形在程序中经常遇到,下面是我做的一个拖动复制控件的示例,仅供有这种需求的朋友们参考。

  新建一个 Silverlight 项目命名为 DragAndCopy ,在新建的项目中添加一个Silverlight 用户控件(Silverlight user control)命名为 DragObject。项目结构如下图所示:Silverlight项目结构

  其中 DragObject 就是要拖动的用户控件,DragObject 的 Xaml 代码如下:

<UserControl x:Class="DragAndCopy.DragObject"
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"
mc:Ignorable
="d"
d:DesignHeight
="300" d:DesignWidth="400">
<Image x:Name="icon" Width="128" Height="128" Stretch="Fill" />
</UserControl>

  这里只是演示拖动复制效果,只在 DragObject 中显示一个图标。DragObject 的后置代码如下:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Imaging;

namespace DragAndCopy
{
public partial class DragObject : UserControl
{
public DragObject()
{
InitializeComponent();

this.Loaded += new RoutedEventHandler(DragObject_Loaded);
}

/// <summary>
/// 唯一标识一个控件
/// </summary>
public string UUID
{
get;
set;
}

/// <summary>
/// 鼠标点击的位置
/// </summary>
public Point ClickPos
{
get;
set;
}

/// <summary>
/// 图标地址(相对)
/// </summary>
public string ImageUri
{
get;
set;
}

void DragObject_Loaded(object sender, RoutedEventArgs e)
{
if (!string.IsNullOrEmpty(ImageUri))
{
BitmapImage bitmap
= new BitmapImage(new Uri(ImageUri, UriKind.Relative));
icon.Source
= bitmap;
}
}
}
}
  DragObject 的 UUID 属性用来唯一标识一个 DragObject 实例,在鼠标点击 DragObject 时也是通过 UUID 来判断是进行移动还是复制。ClickPos 属性是鼠标点击 DragObject 的位置,ImageUri 属性是 DragObject 的图标的相对地址。

  接下来在 MainPage 中添加几个 DragObject 的实例,并添加一 Canvas 容器。

<UserControl x:Class="DragAndCopy.MainPage"
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:DragAndCopy"
mc:Ignorable
="d"
d:DesignHeight
="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<Grid.RowDefinitions>
<RowDefinition Height="160" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Border Grid.Row="0" CornerRadius="5,5,5,5" BorderBrush="Green" BorderThickness="1,1,1,1">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="5,10,5,10">
<local:DragObject ImageUri="icons/chrome.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
<local:DragObject ImageUri="icons/flock.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
<local:DragObject ImageUri="icons/galeon.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
<local:DragObject ImageUri="icons/ie7.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
<local:DragObject ImageUri="icons/konqueror.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
<local:DragObject ImageUri="icons/mfirefox.png"
Margin
="5,5,5,5"
MouseLeftButtonDown
="Handle_MouseLeftButtonDown"
MouseLeftButtonUp
="Handle_MouseLeftButtonUp" />
</StackPanel>
</Border>

<Canvas x:Name="rootCanvas" Grid.Row="1" Background="White">

</Canvas>
</Grid>
</UserControl>

  接着实现将 DragObject 从 StackPanel 容器中拖动到 Canvas 容器中时,复制一个 DragObject 到 Canvas 容器。拖动复制这个动作是在 StackPanel 中的 DragObject 上按下鼠标左键,然后将鼠标指针拖动到 Canvas 中后弹起鼠标左键,由此可知 StackPanel 中的 DragObject 需要响应鼠标左键的按下事件,Canvas 需要响应鼠标左键的弹起事件。

  先定义两个变:

private DragObject curDrag;
private bool isMouseCaptured;

  curDrag 是用来保存要复制的控件的中间变量,isMouseCaptured 用来判断是否按鼠标左键。

  事件处理代码如下:

void Handle_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)?
{
DragObject dragObj
= sender as DragObject;
if (dragObj != null) // 鼠标左键在 DragObject 上按下
{
if (string.IsNullOrEmpty(dragObj.UUID)) // 在控件栏中的 DragObject 上按下
{
// 复制要拖动的控件
curDrag = new DragObject();
curDrag.UUID
= Guid.NewGuid().ToString("N"); // 使用 Guid 标识复制的每个控件
curDrag.ImageUri = dragObj.ImageUri;
curDrag.ClickPos
= e.GetPosition(dragObj);
}
isMouseCaptured
= true;
}
}
void Handle_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
DragObject dragObj
= sender as DragObject;
if (sender is Canvas) // 鼠标左键在容器上弹起
{
if (isMouseCaptured)
{
isMouseCaptured
= false;
if (!rootCanvas.Children.Contains(curDrag)) // 复制控件
{
double x = e.GetPosition(rootCanvas).X;
double y = e.GetPosition(rootCanvas).Y;

rootCanvas.Children.Add(
new DragObject
{
ImageUri
= curDrag.ImageUri,
UUID
= curDrag.UUID,
ClickPos
= curDrag.ClickPos
});

// 添加控件的鼠标左键按下、弹起事件、设置控件的位置
DragObject obj = rootCanvas.Children.First(ue => (ue as DragObject).UUID == curDrag.UUID) as DragObject;
//obj.MouseMove += Handle_MouseMove;
obj.MouseLeftButtonDown += Handle_MouseLeftButtonDown;

obj.SetValue(Canvas.TopProperty, y
- obj.ClickPos.Y);
obj.SetValue(Canvas.LeftProperty, x
- obj.ClickPos.X);
}
}
}
}

  有了以上的代码就可以实现用户控件的复制了。接下实现 Canvas 容器中的控件的拖动事件,拖动控件的是在控件上按下鼠标左键,然后移动鼠标,因此控件需要处理鼠标左键按下和鼠标移动事件。处理代码如下:

void Handle_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DragObject dragObj
= sender as DragObject;
if (dragObj != null) // 鼠标左键在 DragObject 上按下
{
dragObj.MouseMove
-= Handle_MouseMove;
dragObj.MouseMove
+= Handle_MouseMove;

mouseVerticalPosition
= e.GetPosition(null).Y;
mouseHorizontalPosition
= e.GetPosition(null).X;
dragObj.CaptureMouse();
isMouseCaptured
= true;
}
}

  鼠标移动事件处理代码如下:

void Handle_MouseMove(object sender, MouseEventArgs e)
{
DragObject item
= sender as DragObject;

if (item != null && isMouseCaptured)
{
double deltaV = e.GetPosition(null).Y - mouseVerticalPosition;
double deltaH = e.GetPosition(null).X - mouseHorizontalPosition;
double newTop = deltaV + (double)item.GetValue(Canvas.TopProperty);
double newLeft = deltaH + (double)item.GetValue(Canvas.LeftProperty);

// 设置新位置
item.SetValue(Canvas.TopProperty, newTop);
item.SetValue(Canvas.LeftProperty, newLeft);

// 更新全局变量
mouseVerticalPosition = e.GetPosition(null).Y;
mouseHorizontalPosition
= e.GetPosition(null).X;
}
}

  通过以上代码我们实现的拖动复制及移动控件,但是上面的代码还有一些小 Bug, 完整的示例代码请到http://zdd.me/myfiles下载。

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标签:Silverlight

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