在工作中经常会遇到需要将一组数据绘制成曲线图的情况，最简单的方法是将数据导入Excel，然后使用绘图功能手动生成曲线图。但是如果基础数据频繁更改，则手动创建图形可能会变得枯燥乏味。本篇将利用DynamicDataDisplay 在WPF 中动态模拟CPU 使用率图表，实现动态生成曲线图。

新建项目将DynamicDataDisplay.dll 加载到References 中，打开MainWindow.xaml 添加命名空间xmlns:d3="http://research.microsoft.com/DynamicDataDisplay/1.0"。通过<d3:ChartPlotter> 创建一个图表框架，在其中添加两条整型坐标轴，X轴：<d3:HorizontalIntegerAxis>，Y轴：<d3:VerticalIntegerAxis>。<d3:Header> 用来设置图表名称，<d3:VerticalAxisTitle> 用来设置Y轴名称。

<Window x:Class="WpfPerformance.MainWindow"        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        xmlns:d3="http://research.microsoft.com/DynamicDataDisplay/1.0"        Title="CPU Performance" Loaded="Window_Loaded" Height="350" Width="525">    <Grid>        <Grid.RowDefinitions>            <RowDefinition Height="Auto"/>            <RowDefinition Height="*"/>        </Grid.RowDefinitions>        <StackPanel Orientation="Horizontal">            <TextBlock Text="CPU Usage" Margin="20,10,0,0"                       FontSize="15" FontWeight="Bold"/>            <TextBlock x:Name="cpuUsageText" Margin="10,10,0,0"                       FontSize="15"/>        </StackPanel>        <d3:ChartPlotter x:Name="plotter" Margin="10,10,20,10" Grid.Row="1">            <d3:ChartPlotter.VerticalAxis>                <d3:VerticalIntegerAxis />            </d3:ChartPlotter.VerticalAxis>            <d3:ChartPlotter.HorizontalAxis>                <d3:HorizontalIntegerAxis />            </d3:ChartPlotter.HorizontalAxis>            <d3:Header Content="CPU Performance History"/>            <d3:VerticalAxisTitle Content="Percentage"/>        </d3:ChartPlotter>    </Grid></Window>

XAML

　　接下来工作需要通过C#每秒获取一次CPU使用率，并将这些数据生成坐标点（Point）绘制在图表中。以下是MainWindow.xaml.cs 部分的代码内容。

using System;using System.Diagnostics;using System.Windows;using System.Windows.Media;using System.Windows.Threading;using Microsoft.Research.DynamicDataDisplay;using Microsoft.Research.DynamicDataDisplay.DataSources;namespace WpfPerformance{    public partial class MainWindow : Window    {        private ObservableDataSource<Point> dataSource = new ObservableDataSource<Point>();        private PerformanceCounter cpuPerformance = new PerformanceCounter();        private DispatcherTimer timer = new DispatcherTimer();        private int i = 0;        public MainWindow()        {            InitializeComponent();        }        private void AnimatedPlot(object sender, EventArgs e)        {            cpuPerformance.CategoryName = "Processor";            cpuPerformance.CounterName = "% Processor Time";            cpuPerformance.InstanceName = "_Total";            double x = i;            double y = cpuPerformance.NextValue();            Point point = new Point(x, y);            dataSource.AppendAsync(base.Dispatcher, point);            cpuUsageText.Text = String.Format("{0:0}%", y);            i++;        }        private void Window_Loaded(object sender, RoutedEventArgs e)        {            plotter.AddLineGraph(dataSource, Colors.Green, 2, "Percentage");            timer.Interval = TimeSpan.FromSeconds(1);            timer.Tick += new EventHandler(AnimatedPlot);            timer.IsEnabled = true;            plotter.Viewport.FitToView();        }    }}

通过ObservableDataSource<Point> 动态存储图表坐标点，PerformanceCounter 获取CPU使用率数值，DispatcherTimer 计时器在规定间隔进行取数操作，整型i 作为CPU使用率坐标点的X轴数值。

private ObservableDataSource<Point> dataSource = new ObservableDataSource<Point>();private PerformanceCounter cpuPerformance = new PerformanceCounter();private DispatcherTimer timer = new DispatcherTimer();private int i = 0;

AnimatedPlot 事件用于构造坐标点，通过设置cpuPerformance 相关参数，并使用NextValue() 方法获取当前CPU使用率数据作为Y值，整型i 作为X值。将X、Y值构造为坐标点（Point），并通过异步方式存储在dataSource 中。

private void AnimatedPlot(object sender, EventArgs e){    cpuPerformance.CategoryName = "Processor";    cpuPerformance.CounterName = "% Processor Time";    cpuPerformance.InstanceName = "_Total";    double x = i;    double y = cpuPerformance.NextValue();    Point point = new Point(x, y);    dataSource.AppendAsync(base.Dispatcher, point);    cpuUsageText.Text = String.Format("{0:0}%", y);    i++;}

最后通过Window_Loaded 将事件加载到<Window> 中，AddLineGraph 方法将dataSource 中的坐标点绘制到图表中，曲线颜色定义为绿色，粗细设置为2，曲线名称为"Percentage"。设置计时器间隔为1秒，连续执行AnimatedPlot 事件实时绘制新坐标点。

private void Window_Loaded(object sender, RoutedEventArgs e){    plotter.AddLineGraph(dataSource, Colors.Green, 2, "Percentage");    timer.Interval = TimeSpan.FromSeconds(1);    timer.Tick += new EventHandler(AnimatedPlot);    timer.IsEnabled = true;    plotter.Viewport.FitToView();}

CPU