如何在WinForms C＃中使用LiveCharts库创建饼图

本文概述

• 1.安装LiveCharts
• 2.添加一个PieChart组件
• 3.在PieChart上显示数据
• 4.自定义PieChart

当你需要处理科学主题, 数据可视化(或最简单的为仪表盘创建图表)时, 饼图无疑是显示简单数据的最常用和最广为人知的方法之一。饼图用于显示某个值的总和的百分比, 因此所有切片(段)的总和必须为100％。如果你愿意在WinForms应用程序中显示此类图表, 建议你为此使用一个库, 而不是使用.NET的Drawing类进行绘制

在本文中, 我们将向你展示如何使用LiveCharts库在带有C＃的WinForms应用程序中显示饼图。

1.安装LiveCharts

要在Visual Studio中的项目上安装此软件包, 请转到解决方案资源管理器, 然后右键单击你的项目。从下拉列表中选择管理NuGet软件包选项：

在管理器中, 转到浏览选项卡并搜索LiveCharts包：

选择Beto Rodriguez的WinForms软件包并将其安装在你的项目中。安装完成后, 你将可以使用该库在代码上呈现图表。有关此库的更多信息, 请访问Github上的官方存储库。

2.添加一个PieChart组件

在项目中安装LiveCharts库后, Visual Studio会自动添加一组新控件, 使你可以将图表添加到WinForms布局中。打开表单设计器时, 可以在Visual Studio的左侧找到它。为了开始本文的示例, 我们将添加一个PieChart项, 因此只需将其拖放到表单中即可：

这将添加默认图像, 以让你知道该组件正在占用空间(数据没有意义)。默认情况下, 第一个项目在代码中将被命名为pieChart1, 但是你可以稍后更改组件的名称。在我们的示例中, 我们将保留第一个元素的相同名称。

3.在PieChart上显示数据

现在你的表单以图形方式显示了一个PieChart, 你需要设置一些将要绘制的数据。首先, 你需要定义一个包含PieSeries元素的数据集合, 这些元素可以在SeriesCollection对象中进行动态或静态定义。每个PieSeries对象至少需要定义Title, LabelPoint和Values选项才能正确显示。可以使用ChartValues类的新实例及其类型和原始值来定义每个项目的值。

可以根据需要在集合上添加数据, 也可以立即在SeriesCollection构造函数中对其进行定义：

// Include the required namespace of LiveCharts
using LiveCharts;
using LiveCharts.Wpf;

// It's important to run the code inside the load event of the form, so the component will be drawn after this correctly
private void Form1_Load(object sender, EventArgs e)
{
    // Define the label that will appear over the piece of the chart
    // in this case we'll show the given value and the percentage e.g 123 (8%)
    Func<ChartPoint, string> labelPoint = chartPoint => string.Format("{0} ({1:P})", chartPoint.Y, chartPoint.Participation);

    // Define a collection of items to display in the chart 
    SeriesCollection piechartData = new SeriesCollection
    {
        new PieSeries
        {
            Title = "First Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint
        }, new PieSeries
        {
            Title = "Second Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint
        }, new PieSeries
        {
            Title = "Third Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint
        }
    };

    // You can add a new item dinamically with the add method of the collection
    // Useful when you define the data dinamically and not statically
    piechartData.Add(
        new PieSeries{
            Title = "Fourth Item", Values = new ChartValues<double> { 25 }, DataLabels = true, LabelPoint = labelPoint, Fill = System.Windows.Media.Brushes.Gray
        }
    );

    // Define the collection of Values to display in the Pie Chart
    pieChart1.Series = piechartData;

    // Set the legend location to appear in the Right side of the chart
    pieChart1.LegendLocation = LegendLocation.Right;
}

如前所述, 代码需要在表单加载事件之后/期间执行。以下示例显示了文章开头显示的图形, 该图形显示了该国核弹头的数量和百分比：

using System;
using System.Windows.Forms;

// Include the required namespace of LiveCharts
using LiveCharts;
using LiveCharts.Wpf;

namespace Sandbox
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // Define the label that will appear over the piece of the chart
            // in this case we'll show the given value and the percentage e.g 123 (8%)
            Func<ChartPoint, string> labelPoint = chartPoint => string.Format("{0} ({1:P})", chartPoint.Y, chartPoint.Participation);

            // Define the collection of Values to display in the Pie Chart
            pieChart1.Series = new SeriesCollection
            {
                new PieSeries
                {
                    Title = "USA", Values = new ChartValues<double> {6450}, DataLabels = true, LabelPoint = labelPoint, }, new PieSeries
                {
                    Title = "Russia", Values = new ChartValues<double> {6850}, DataLabels = true, LabelPoint = labelPoint
                }, new PieSeries
                {
                    Title = "United Kingdom", Values = new ChartValues<double> {215}, DataLabels = true, LabelPoint = labelPoint
                }, new PieSeries
                {
                    Title = "France", Values = new ChartValues<double> {300}, DataLabels = true, LabelPoint = labelPoint
                }, new PieSeries
                {
                    Title = "China", Values = new ChartValues<double> {280}, DataLabels = true, LabelPoint = labelPoint
                }
            };

            // Set the legend location to appear in the bottom of the chart
            pieChart1.LegendLocation = LegendLocation.Bottom;
        }
    }
}

4.自定义PieChart

对于定制, 几乎每个人都需要的是基本功能。例如, 要更改颜色, 你需要定义System.Windows.Media.Brushes密封类的填充颜色：

new PieSeries
{
    Title = "Second Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint, // Define the piece with a green color
    Fill = System.Windows.Media.Brushes.Green
}

或者, 如果要突出显示饼图中的某段, 请使用PushOut选项：

new PieSeries
{
    Title = "Second Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint, // Highligh this piece of the chart
    PushOut = 15, }

如下代码：

// Define the label that will appear over the piece of the chart
// in this case we'll show the given value and the percentage e.g 123 (8%)
Func<ChartPoint, string> labelPoint = chartPoint => string.Format("{0} ({1:P})", chartPoint.Y, chartPoint.Participation);

SeriesCollection piechartData = new SeriesCollection
{
    new PieSeries
    {
        Title = "First Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint, // Define a custom Color 
        Fill = System.Windows.Media.Brushes.Black
    }, new PieSeries
    {
        Title = "Second Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint, Fill = System.Windows.Media.Brushes.Green, PushOut = 15
    }, new PieSeries
    {
        Title = "Third Item", Values = new ChartValues<double> {25}, DataLabels = true, LabelPoint = labelPoint, Fill = System.Windows.Media.Brushes.Pink
    }
};

// You can add a new item dinamically with the add method of the collection
piechartData.Add(
    new PieSeries{
        Title = "Fourth Item", Values = new ChartValues<double> { 25 }, DataLabels = true, LabelPoint = labelPoint, Fill = System.Windows.Media.Brushes.Gray
    }
);

// Define the collection of Values to display in the Pie Chart
pieChart1.Series = piechartData;

// Set the legend location to appear in the bottom of the chart
pieChart1.LegendLocation = LegendLocation.Right;

将生成以下图表：

编码愉快！