Silverlight撤消重做功能的实现。

想实现类似画图工具那样，重做撤消可以恢复或擦除最后一次的绘图。

不知道通用的方法是什么，自己琢磨了这样的方法，请高手指教。

<UserControl x:Class="SilverlightUndo.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" 
    mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">
  <Grid x:Name="LayoutRoot">
        <Grid.RowDefinitions>
            <RowDefinition Height="50"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="50"></ColumnDefinition>
            <ColumnDefinition Width="50"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Button Grid.Row="0" Grid.Column="0" Content="重做" Name="btnRedo" Click="btnRedo_Click"></Button>
        <Button Grid.Row="0" Grid.Column="1" Content="撤消" Name="btnUndo" Click="btnUndo_Click"></Button>
        <Canvas Name="Board" MouseLeftButtonDown="Canvas_MouseLeftButtonDown" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" Background="Black"></Canvas>
    </Grid>
</UserControl>

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 SilverlightUndo
{
    public partial class MainPage : UserControl
    {
        private bool IsStart = true;//是否是起点。
        private double pX1 = 0, pY1 = 0;//起点坐标
        Line[] arrLine = new Line[100];//silverlight不支持ArrayList之类。
        int iCount = 0;//计数器

        public MainPage()
        {
            InitializeComponent();
        }

        private void Canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            Point p = e.GetPosition(sender as FrameworkElement);//取得鼠标点下的位置
            Canvas pnl = sender as Canvas;
            if (IsStart)
            {
                pX1 = p.X;//设置起点坐标
                pY1 = p.Y;
            }
            if (IsStart)//如果是起点，则画起点。
            {
                DrawPoint(pnl, p.X, p.Y);
            }
            else
            {
                DrawOneLine(pnl, pX1, pY1, p.X, p.Y);
            }
            IsStart = !IsStart;
        }
        //画点
        private void DrawPoint(Canvas pnl, double pX1, double pY1)
        {
            Ellipse ellipse = new Ellipse();//画点
            ellipse.Stroke = new SolidColorBrush(Color.FromArgb(255, 255, 255, 255));//动态设置Stroke属性的方法。
            ellipse.StrokeThickness = 2;
            ellipse.Width = 4;
            ellipse.Height = 4;
            Canvas.SetLeft(ellipse, pX1);//动态设置Ellipse的Canvas.Top与Canvas.Left
            Canvas.SetTop(ellipse, pY1);

            pnl.Children.Add(ellipse);
        }
        //画直线
        private void DrawOneLine(Canvas pnl, double pX1, double pY1, double pX2, double pY2)
        {
            Line line = new Line();
            line.X1 = pX1;
            line.Y1 = pY1;
            line.X2 = pX2;
            line.Y2 = pY2;

            line.Stroke = new SolidColorBrush(Color.FromArgb(255, 255, 255, 255));
            line.StrokeThickness = 4;

            pnl.Children.Add(line);

            //计数器
            arrLine[iCount] = line;
            iCount += 1;
        }

        private void btnRedo_Click(object sender, RoutedEventArgs e)
        {
            if (arrLine[iCount] != null)
            {
                Board.Children.Add(arrLine[iCount]);
                iCount += 1;
            }
        }

        private void btnUndo_Click(object sender, RoutedEventArgs e)
        {
            if (iCount == 0) return;
            if (arrLine[iCount - 1] != null)
            {
                Board.Children.Remove(arrLine[iCount - 1]);
                iCount -= 1;
            }
        }
    }
}

 

源码：https://files.cnblogs.com/greatverve/SilverlightUndo.rar