chart.cs

网上书店系统

using System;
using System.IO;
using System.Data;
using System.Drawing;
using System.Drawing.Text;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

namespace eBookShop.BLL
{
    /// <summary>
    /// 一个通用的画饼图的类
    /// </summary>
    public class Chart
    {
        private const int SIDE_LENGTH = 400;
        private const int PIE_DIAMETER = 200;

        /// <summary>
        /// 画饼图方法
        /// </summary>
        /// <param name="title">饼图标题</param>
        /// <param name="subTitle">子标题</param>
        /// <param name="width">宽</param>
        /// <param name="height">高</param>
        /// <param name="dt">数据来源表</param>
        /// <param name="targetFile">生成的图形保存目标文件</param>
        /// <param name="descColumn">文字说明列</param>
        /// <param name="dataColumn">显示在统计图上的数据列名</param>
        public static void DrawPie(string title, string subTitle, int width, int height, DataTable dt, string targetFile, string descColumn, string dataColumn)
        {
            //创建一个位图对象
            Bitmap bm = new Bitmap(width, height);
            Graphics g = Graphics.FromImage(bm);

            //将图象"缩放"到指定面积
            g.ScaleTransform(Convert.ToSingle(width) / SIDE_LENGTH, Convert.ToSingle(height) / SIDE_LENGTH);

            //画饼图所在的线框
            g.Clear(Color.White);
            g.DrawRectangle(Pens.Black, 0, 0, SIDE_LENGTH - 1, SIDE_LENGTH - 1);

            //画标题title,副标题subTitle
            g.DrawString(title, new Font("宋体", 14), Brushes.Black, new PointF(5, 5));
            g.DrawString(subTitle, new Font("宋体", 12), Brushes.Black, new PointF(7, 35));

            //画饼图
            float curAngle = 0;		//当前所画到的角度
            float totalAngle = 0;		//总的角度
            float sumData = 0;		//计算所要统计的数据之和

            //计算所要统计的数据之和
            foreach (DataRow dr in dt.Rows)
            {
                if (dr[dataColumn] != DBNull.Value)
                    sumData += Convert.ToSingle(dr[dataColumn]);
            }

            //循环画出每一个扇形,以及其说明
            int colorIndex = 0;		//颜色
            float percent = 0;		//每一个种类的百分比
            g.DrawRectangle(Pens.Black, 100, 270, 300, 130);	//说明线框
            PointF boxOrigin = new PointF(110, 275);			//说明标签起始位置
            PointF textOrigin = new PointF(135, 275);			//说明文字起始位置

            //循环画出每一个扇形
            foreach (DataRow row in dt.Rows)
            {
                if (row[dataColumn] != System.DBNull.Value)
                {
                    colorIndex++;

                    //扇形
                    curAngle = Convert.ToSingle(row[dataColumn]) / sumData * 360;
                    g.FillPie(new SolidBrush(GetColor(colorIndex)), 100, 60, PIE_DIAMETER, PIE_DIAMETER, totalAngle, curAngle);
                    g.DrawPie(Pens.Black, 100, 60, PIE_DIAMETER, PIE_DIAMETER, totalAngle, curAngle);
                    totalAngle += curAngle;

                    //标签
                    g.FillRectangle(new SolidBrush(GetColor(colorIndex)), boxOrigin.X, boxOrigin.Y, 20, 10);
                    g.DrawRectangle(Pens.Black, boxOrigin.X, boxOrigin.Y, 20, 10);

                    //说明
                    percent = Convert.ToSingle(row[dataColumn]) / sumData * 100;
                    g.DrawString(
                        row[descColumn].ToString() + "（" + percent.ToString("0.0") + "%）",
                        new Font("宋体", 12), Brushes.Black, textOrigin
                        );

                    boxOrigin.Y += 20;
                    textOrigin.Y += 20;
                }
            }

            //将生成的图保存到target
            bm.Save(targetFile, ImageFormat.Gif);

            //释放资源
            bm.Dispose();
            g.Dispose();
        }

        /// <summary>
        /// 生成颜色的方法
        /// </summary>
        /// <param name="itemIndex"></param>
        /// <returns></returns>
        public static Color GetColor(int idx)
        {
            idx *= 60;
            int r = idx % 255;
            int g = ((255 / 3) + idx) % 255;
            int b = ((255 * 2 / 3) + idx) % 255;
            return Color.FromArgb(r, g, b);
        }
    }
}