c# 柱状图（转载）

// c# 显示柱状图

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing.Imaging;
using System.Drawing;
/// <summary>
/// DrawingCurve 的摘要说明
/// </summary>
public class DrawingCurve
{

public int intXLong = 800;   //图片大小 长
public int intYLong = 600;   //图片大小 高
public int intXMultiple = 1;    //零刻度的值 X
public int intYMultiple = 0;    //零刻度的值 Y
public int intXMax = 12;    //最大刻度(点数) X
public int intYMax = 30;    //最大刻度(点数) Y

public int intLeft = 50;   //左边距
public int intRight = 120; //右边距
public int intTop = 30;    //上边距
public int intEnd = 50;    //下边距

public string strXText = "时间(单位:月)";    //单位 X
public string strYText = "数量(单位:个)";    //单位 Y
public string strTitle = "趋势线图";    //标题
public DataTable tbData;    //要统计的数据

private int intXScale = 30;    //一刻度长度 X
private int intYScale = 30;    //一刻度高度 Y
//private int intX = 0;   //0点 X坐标
//private int intY = 0;   //0点 Y坐标
public int intData = 0;    //记录数

public DrawingCurve()
{

intXScale = (intXLong - intLeft - intRight) / (intXMax + 1);//一刻度长度 X
intYScale = (intYLong - intTop - intEnd) / (intYMax + 1);//一刻度高度 Y

//intX = intXLong - intLeft;   //0点 X坐标
//intY = intYLong - intEnd;   //0点 Y坐标
}

public Bitmap DrawingImg()
{

Bitmap img = new Bitmap(intXLong, intYLong); //图片大小
Graphics g = Graphics.FromImage(img);
g.Clear(Color.Snow);
g.DrawString(strTitle, new Font("宋体", 14), Brushes.Black, new Point(5, 5));
g.DrawLine(new Pen(Color.Black, 2), intLeft, intYLong - intEnd, intXLong - intRight, intYLong - intEnd); //绘制横向
g.DrawLine(new Pen(Color.Black, 2), intLeft, intTop, intLeft, intYLong - intEnd);   //绘制纵向

//绘制纵坐标
g.DrawString(strYText, new Font("宋体", 12), Brushes.Black, new Point(intLeft, intTop));//Y 单位
Point p1 = new Point(intLeft - 10, intYLong - intEnd);
for (int j = 0; j <= intYMax; j++)
{
p1.Y = intYLong - intEnd - j * intYScale;
Point pt = new Point(p1.X + 10, p1.Y);
//绘制纵坐标的刻度和直线
g.DrawLine(Pens.Black, pt, new Point(p1.X + 15, p1.Y));
//绘制纵坐标的文字说明
g.DrawString(Convert.ToString(j + intYMultiple), new Font("宋体", 12), Brushes.Black, new Point(p1.X - 25, p1.Y - 8));
}

//绘制横坐标
g.DrawString(strXText, new Font("宋体", 12), Brushes.Black, new Point(intXLong - intRight, intYLong - intEnd));//X 单位
Point p = new Point(intLeft, intYLong - intEnd);
for (int i = 0; i < intXMax; i++)
{
p.X = intLeft + i * intXScale;
//绘制横坐标刻度和直线
g.DrawLine(Pens.Black, p, new Point(p.X, p.Y - 5));
//绘制横坐标的文字说明
g.DrawString(Convert.ToString(i + intXMultiple), new Font("宋体", 12), Brushes.Black, p);
}

intData = tbData.Rows.Count;
if (intData > 0)
{
//趋势线图
for (int i = 0; i < intData - 1; i++)
{
DataRow Row1 = tbData.Rows[i];
DataRow Row2 = tbData.Rows[i + 1];
//定义起点
Point rec = new Point(Convert.ToInt32(intLeft + ((TurnNumber(Row1[0].ToString()) - intXMultiple) * intXScale)), Convert.ToInt32(intYLong - intEnd - (TurnNumber(Row1[1].ToString()) - intYMultiple) * intYScale));
//定义终点
Point dec = new Point(Convert.ToInt32(intLeft + ((TurnNumber(Row2[0].ToString()) - intXMultiple) * intXScale)), Convert.ToInt32(intYLong - intEnd - (TurnNumber(Row2[1].ToString()) - intYMultiple) * intYScale));
//绘制趋势折线
g.DrawLine(new Pen(Color.Red), rec, dec);
}
}

return img;
}

//转换数字
private double TurnNumber(string str)
{
double dubReturn;
try
{
dubReturn = Convert.ToDouble(str);
}
catch
{
dubReturn = 0;
}
return dubReturn;

}

}

----------------------------------调用------------------------------------------------

protected void Page_Load(object sender, EventArgs e)
{
DataTable MyTable = new DataTable();

string constr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("App_Data/db.mdb");
string cmdstr = "SELECT 月份,销量 FROM Result";
OleDbConnection con = new OleDbConnection(constr);
con.Open();
//OleDbCommand cmd = new OleDbCommand(cmdstr, con);
OleDbDataAdapter da = new OleDbDataAdapter(cmdstr, con);
da.Fill(MyTable);

DrawingCurve MyDc = new DrawingCurve();
MyDc.tbData = MyTable;

Bitmap img = new Bitmap(100, 100);
img = MyDc.DrawingImg();
Graphics g = Graphics.FromImage(MyDc.DrawingImg());

//显示图形
img.Save(Response.OutputStream, ImageFormat.Jpeg);;
g.Dispose();
Response.Write("<br>" + MyDc.intData.ToString());
}