.net使用gdi+绘半饼图

最新推荐文章于 2025-07-25 10:59:24 发布

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本文介绍了一种使用GDI+在Web项目中绘制半饼图的方法。通过解析XML数据确定各扇区的颜色和大小，并计算每个区域的角度。文章还提供了具体的代码实现，包括如何绘制文字坐标。

前两天web项目中遇到要绘一个半饼图，图表控件中没有这样的图，就用gdi+简单的绘了一个。

实现思路：

基于xml进行半饼图的数据提供，格式如下：

半饼图中每个区域可以分别指定颜色。每个区域的大小由提供数据的data属性值决定。每个区域的角度大小为：

iCurrAngle = Convert.ToInt32(当前区域数据 / 所有区域数据和 * 180);，因为是半饼图所以*180度。对于每个区域上绘制文字坐标，使用放大半径求圆弧所在点的位置的方式。

具体实现如下：

BaseDraw：绘图基类

PartPieDraw:绘半饼图实现类，主要是 RenerImage方法

using System;
using System.Collections;
using System.Drawing;
using System.Drawing.Drawing2D;

/// <summary>
/// BaseDraw 的摘要说明
/// </summary>
public class BaseDraw
{
    private int imageWidth = 0;
    private int imageHeight = 0;
    private string xmlData = "";

    public BaseDraw()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

    public int ImageWidth
    {
        get { return this.imageWidth; }
        set { this.imageWidth = value; }
    }

    public int ImageHeight
    {
        get { return this.imageHeight; }
        set { this.imageHeight = value; }
    }

    public string XmlData
    {
        get { return this.xmlData; }
        set { this.xmlData = value; }
    }

    public byte[] Draw()
    {
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(this.imageWidth,this.imageHeight);
        Graphics g = Graphics.FromImage(image);
        this.RenerImage(g);
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
        byte[] buffer = ms.ToArray();
        g.Dispose();
        image.Dispose();
        return buffer;
    }

    public virtual ArrayList ParseXmlData()
    {
        return null;
    }

    public virtual void RenerImage(Graphics g)
    {

    }
}

using System;
using System.Collections;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Xml;

/// <summary>
/// PartPieDraw 的摘要说明
/// </summary>
public class PartPieDraw:BaseDraw
{
    public PartPieDraw()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

    public override void RenerImage(System.Drawing.Graphics g)
    {
        ArrayList dataList = this.ParseXmlData();
        //开始计算总的数值
        double sumValue = 0.00;
        foreach (ImageData data in dataList)
        {
            sumValue += Convert.ToDouble(Math.Round(data.DrawData, 2));
        }
        sumValue = Convert.ToDouble(Math.Round(sumValue, 2));
        int iSumAngle = 180;    //总要绘的角度
        int iCurrAngle = 0;   //当前角度
        int iPosAngle = 180;   //当前角度的基值
        int iCurrSumAngle = 0;
        double dCurrBfb = 0;
        //定义半图所在的矩形区域大小,画缓的位置占整个图的2/3
        int iAreaX = Convert.ToInt32((this.ImageWidth - Convert.ToInt32(this.ImageWidth * 2 / 3)) / 2);
        int iAreaY = iAreaX;
        int iAreaWidth = Convert.ToInt32(this.ImageWidth * 2 / 3);    //长边
        int iAreaHeight = iAreaWidth;
        double r = iAreaWidth / 2;    //半径
        double rx = Convert.ToDouble(iAreaX) + r;    //圆心x
        double ry = Convert.ToDouble(iAreaY) + r;    //圆心y
        //重设置半径
        r += 20;
        g.Clear(Color.White); //清除背景
        g.SmoothingMode = SmoothingMode.AntiAlias; //消除绘的时候的锯齿
        g.DrawRectangle(new System.Drawing.Pen(Color.Black, 1), 0, 0, this.ImageWidth, this.ImageHeight);
        for (int i = 0; i < dataList.Count; i++)
        {
            ImageData imageData = (ImageData)dataList[i];
            dCurrBfb += imageData.DrawData / sumValue * 100;
            dCurrBfb = Convert.ToDouble(Math.Round(dCurrBfb, 2)); //格式化两位小数
            if (i < dataList.Count - 1)
            {
                iCurrAngle = Convert.ToInt32(imageData.DrawData / sumValue * iSumAngle);
            }
            else
            {
                iCurrAngle = 360 - iPosAngle;
            }
            g.SmoothingMode = SmoothingMode.AntiAlias; //消除绘的时候的锯齿
            g.FillPie(new SolidBrush(imageData.DrawColor), iAreaX, iAreaY, iAreaWidth, iAreaHeight, iPosAngle, iCurrAngle);
            g.DrawPie(new Pen(new SolidBrush(imageData.DrawColor)), iAreaX, iAreaY, iAreaWidth, iAreaHeight, iPosAngle, iCurrAngle);
            //计算绘数字
            //求圆弧所在点的位置,有偏差
            iCurrSumAngle += iCurrAngle;
            double pointX = Math.Cos(iCurrSumAngle * Math.PI / 180) * r; //对边,
            double pointY = Math.Sin(iCurrSumAngle * Math.PI / 180) * r; //邻边
            pointY = ry - pointY;

            pointX = rx - pointX;
            Font strFont=new Font("宋体", 12, FontStyle.Italic);
            //开始测试绘字符需要的位置
            SizeF sizeF = g.MeasureString(dCurrBfb.ToString(), strFont);

            pointX = pointX - sizeF.Width / 2;
            pointY = pointY + sizeF.Height / 2;

            g.DrawString(dCurrBfb.ToString(), strFont, new SolidBrush(Color.Red), Convert.ToInt32(pointX), Convert.ToInt32(pointY) - 20);

            iPosAngle += iCurrAngle;
            iCurrAngle = 0;

        }
    }

    public override ArrayList ParseXmlData()
    {
        //解析数据格式
        //<imagedraw>
        //   <imagedata data="100" color="#fff000">
        //</imagedraw>
        ArrayList dataList = new ArrayList();
        System.Xml.XmlDocument doc = new XmlDocument();
        doc.LoadXml(this.XmlData);
        System.Xml.XmlElement root = doc.DocumentElement;
        foreach (System.Xml.XmlNode node in root.ChildNodes)
        {
            string sData = node.Attributes["data"].Value;
            string sColor = node.Attributes["color"].Value;
            dataList.Add(new ImageData(sData, sColor));
        }
        return dataList;
    }

    public class ImageData
    {
        private double drawData = 0.00;
        private Color drawColor=Color.White;

        public ImageData(string data, string htmlColor)
        {
            this.drawData = Convert.ToDouble(data);
            drawColor = System.Drawing.ColorTranslator.FromHtml(htmlColor);
        }

        public double DrawData
        {
            get { return this.drawData; }
        }

        public Color DrawColor
        {
            get { return drawColor; }
        }

    }

}