动态生成折线图

public class PrintTable : System.Web.UI.Page
    {
        private void Page_Load(object sender, System.EventArgs e)
        {
            if(Session["chuzulv"]!=null)
            {
                //数据源
                Table table=(Table)Session["Chuzulv"];

                //可修改属性
                int Height=300;                                //图像高度
                int Width=500;                                //图像宽度
                string TableName="物资出租率";                //表头
                Font TableHeaderFont=new Font("宋体",12);    //表头字体
                float High=100;                                //默认最大标尺
                float Low=0;                                //默认最小标尺
                Color BGColor=Color.Black;                    //背景色
                Color HLineColor=Color.DarkCyan;            //横向表格线颜色
                Color LineColor=Color.WhiteSmoke;            //曲线颜色

                //临时属性不可修改
                Bitmap bm = new Bitmap(Width,Height);        //图像对象
                Graphics g = Graphics.FromImage(bm);        //绘图对象
                StringFormat drawFormat = new StringFormat();//纵向文字输出格式
                drawFormat.FormatFlags = StringFormatFlags.DirectionVertical;

                SolidBrush br=new SolidBrush(Color.Red);    //Brush,红色
                Pen p =new Pen(Color.Red,1);                //Pen,红色，宽度1
                g.Clear(BGColor);                            //绘制背景色
                g.DrawString(TableName,TableHeaderFont,br,new Point(0,0)); //绘制表头
                int HStep = (Width - 30) / (table.Rows.Count - 1);                //横向步长(每日期)
                int VStep;                                    //纵向步长(每百分点)
                int index=0;                                //临时标示记录索引
                foreach(TableRow r in table.Rows)
                {
                    index++;
                    if (index == 1)                            //过滤数据源第一行Header
                        continue;
                    if (r.Cells[5].Text != "" && float.Parse(r.Cells[5].Text) > High)    //重新获取纵座标上下限
                        High = float.Parse(r.Cells[5].Text);
                    if (r.Cells[5].Text != "" && float.Parse(r.Cells[5].Text) < Low)
                        Low = float.Parse(r.Cells[5].Text);
                }
                High += (High % 10 == 0) ? 0 : 10 - High % 10;//上下限对齐
                Low -= (Low % 10 == 0) ? 0 : 10 + Low % 10;
                VStep = (Height - 50) / (int)(High - Low);    //获取纵向步长

                Point lineStartPoint;                        //曲线起始点
                Point lineEndPoint;                            //曲线终止点
                int BaseVHeight=0;                            //0点纵坐标
                int Vertical=30;                            //横向参考线最高点
                for(float HLine = High ; HLine >= Low ;HLine -= 10)        //绘制横向辅助线
                {
                    g.DrawLine(new Pen(Color.DarkCyan,1),new Point(20,Vertical),new Point(Width,Vertical));
                    g.DrawString(HLine.ToString()+"%",new Font("宋体",8),br,new Point(5,Vertical - VStep ));
                    if(HLine==0)                            
                        BaseVHeight=Vertical;
                    Vertical += VStep * 10;
                }
                Point startPoint=new Point(0,Height-50);
                startPoint.X += 10 ;
                
                lineStartPoint=new Point(startPoint.X  + HStep / 2,BaseVHeight);

                index = 0;
                float PerCent=0;
                foreach(TableRow r in table.Rows)
                {
                    index++;
                    g.DrawString(r.Cells[0].Text,new Font("宋体",8),br,startPoint,drawFormat);
                    if (index == 1)
                        startPoint.X += 20;
                    else
                        startPoint.X += HStep;
                    if (r.Cells[5].Text != "")
                        if (index == 1)
                            continue;
                        else 
                            PerCent = float.Parse(r.Cells[5].Text);
                    else
                        PerCent = 0;
                    if (index == 2)
                        lineStartPoint=new Point(startPoint.X - HStep ,BaseVHeight - (int)PerCent * VStep);
                        
                    lineEndPoint = new Point(startPoint.X - HStep,BaseVHeight - (int)PerCent * VStep);
                    g.DrawLine(new Pen(Color.WhiteSmoke,1),lineStartPoint,lineEndPoint);
                    
                    lineStartPoint = lineEndPoint;
                }
                //输出
                bm.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Gif);
                //清除对象
                ((Table)Session["chuzulv"]).Dispose();
                Session["chuzulv"]=null;
            }
        }

补充一下Session[]==null;无法清除Session对象
还要用Session.Remove(*)来清除

因为报表不需要交互，所以一直用Table，

前一个页统计出Table之后存入Session["chuzulv"]，然后置一Image控件，ImageUrl属性指向此页面

效果如图，上传时压缩了品质，动态生成的Gif效果很不错

转载于:https://www.cnblogs.com/pblee/archive/2005/11/15/276549.html