Silverlight 2动态创建矩形对象(附完整源代码)

使用Silverlight 2的Canvas,写了一个动态创建Rectangle的示例,由于时间的原因所以难免有些不足之处,但程序功能都正常使用.用鼠标可以点击画布任何位置拖出一个矩形对象,松开鼠标即可完成一个矩形的创建!

程序运行效果:

XAML代码:

<UserControl x:Class="Sample.dragrect"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Width="780" Height="400">
    <StackPanel Background="Green" 
                Orientation="Horizontal">
        <Canvas x:Name="LayoutRoot"
                Background="GreenYellow"
                Width="650" Height="400"
                MouseMove="Canvas_MouseMove"
                MouseLeftButtonDown="Canvas_MouseLeftButtonDown" 
                MouseLeftButtonUp="Canvas_MouseLeftButtonUp"/>
        <StackPanel Background="Gold" Margin="10">
            <TextBlock Text="选择颜色："/>
            <Button x:Name="btnRed" 
                    Width="100" Height="50" 
                    FontSize="20" Content="Red" Margin="5" 
                    Click="btnRed_Click"/>
            <Button x:Name="btnBlue" 
                    Width="100" Height="50"
                    FontSize="20" Content="Blue" Margin="5" 
                    Click="btnBlue_Click"/>
            <Button x:Name="btnGreen" 
                    Width="100" Height="50"
                    FontSize="20" Content="Green" Margin="5"
                    Click="btnGreen_Click"/>
            <Button x:Name="btnClear" 
                    Width="100" Height="50"
                    FontSize="20" Content="Clear" Margin="5" 
                    Background="Red"
                    Click="btnClear_Click"/>
        </StackPanel>
    </StackPanel>
</UserControl>
C#代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Sample
{
    public partial class dragrect : UserControl
    {
        public dragrect()
        {
            InitializeComponent();
        }

        bool mouseMoveing = false;
        Point mousePoint;
        Color rectColor = Colors.Red;

        private void Canvas_MouseMove(object sender, MouseEventArgs e)
        {
            //如果鼠标没有拖动矩形则返回
            if (!mouseMoveing)
                return;
            //获取鼠标当前坐标
            Point curPos = e.GetPosition(null);
            //取得最小坐标值
            double posX = mousePoint.X;
            double posY = mousePoint.Y;
            //计算矩形的宽和高
            double rectWidth = Math.Abs(curPos.X - mousePoint.X);
            double rectHeight = Math.Abs(curPos.Y - mousePoint.Y);
            //创建一个矩形元素
            Rectangle rect = new Rectangle();
            //声明矩形的宽和高
            rect.Width = rectWidth;
            rect.Height = rectHeight;
            //填充颜色
            rect.Fill = new SolidColorBrush(rectColor);
            //声明矩形在Canvas中创建的位置
            Canvas.SetLeft(rect, posX);
            Canvas.SetTop(rect, posY);
            //添加矩形到Canvas中
            LayoutRoot.Children.Add(rect);
        }

        private void Canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            //获取当前的鼠标位置
            mousePoint = e.GetPosition(null);
            //开始创建矩形
            mouseMoveing = true;
        }

        private void Canvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            //矩形创建完成
            mouseMoveing = false;
        }

        private void btnRed_Click(object sender, RoutedEventArgs e)
        {
            //声明矩形颜色为Red
            rectColor = Colors.Red;
        }

        private void btnBlue_Click(object sender, RoutedEventArgs e)
        {
            //声明矩形颜色为Blue
            rectColor = Colors.Blue;
        }

        private void btnGreen_Click(object sender, RoutedEventArgs e)
        {
            //声明矩形颜色为Green
            rectColor = Colors.Green;
        }

        private void btnClear_Click(object sender, RoutedEventArgs e)
        {
            //清除所有Canvas内的矩形元素
            LayoutRoot.Children.Clear();
        }
    }
}