GDI+画图类Graphics的使用

一：基础定义

 #region 定义线尾、线头为箭头、字体和笔刷
                Pen p = new Pen(Color.Black, );//定义画笔 蓝色，宽度为1（坐标显示颜色）
                p.EndCap = LineCap.ArrowAnchor;//定义线尾的样式为箭头

                Pen pk = new Pen(Color.Black, );//定义画笔 黑色，宽度为1（坐标显示颜色）
                Pen pbl = new Pen(Color.Red,);
                pbl.EndCap = LineCap.ArrowAnchor;//定义线尾的样式为箭头

                StringFormat strF = new StringFormat(StringFormatFlags.DirectionVertical);//定义格式
                Font f = new System.Drawing.Font("宋体", );//定义字体
                SolidBrush bB = new SolidBrush(Color.Black);//定义单色画刷
                SolidBrush bl = new SolidBrush(Color.Red);//定义单色画刷
            #endregion

二：使用前准备，新建一个picturebox，实例化一个 Graphics类，关联它们

 Graphics gph;//绘画区域
 Bitmap bmp = new Bitmap(pic_Img.Width, pic_Img.Height);//600, 512
                gph = Graphics.FromImage(bmp);

三：实例

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;

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

            #region 定义线尾、线头为箭头、字体和笔刷
            Pen p = new Pen(Color.Blue, );//定义画笔 蓝色，宽度为1（坐标显示颜色）
            p.EndCap = LineCap.ArrowAnchor;//定义线尾的样式为箭头
            p.StartCap = LineCap.ArrowAnchor;//定义线首的样式为箭头

            Font f = new System.Drawing.Font("宋体", );//定义字体
            SolidBrush bB = new SolidBrush(Color.Black);//定义单色画刷
            //SolidBrush bB = new SolidBrush(Color.Blue);
            #endregion
            string[] month = new string[] { "一月", "二月", "三月", "四月", "五月", "六月",
"七月", "八月", "九月", "十月", "十一月", "十二月" };
            float[] d = new float[] { 20.5F, , 10.8F, 15.6F, , 70.9F, 50.3F, 30.7F, , 50.4F, 30.8F,  };
            //画图初始化
            Bitmap bMap = new Bitmap(, );
            Graphics gph = Graphics.FromImage(bMap);
            //gph.Clear(Color.White);
            PointF cPt = new PointF(, );//中心点
            PointF[] xPt = new PointF[]{new PointF(cPt.Y+,cPt.Y),
new PointF(cPt.Y,cPt.Y-),new PointF(cPt.Y,cPt.Y+)};//X轴三角形
            PointF[] yPt = new PointF[]{new PointF(cPt.X,cPt.X-),
new PointF(cPt.X-,cPt.X),new PointF(cPt.X+,cPt.X)};//Y轴三角形
            gph.DrawString("红马車公司月生产量图表", new Font("宋体", )
            , Brushes.Black, new PointF(cPt.X + , cPt.X));//图标标题
            //画X轴
            gph.DrawLine(Pens.Black, cPt.X, cPt.Y, cPt.Y, cPt.Y);
            gph.DrawPolygon(Pens.Black, xPt);
            gph.FillPolygon(new SolidBrush(Color.Black), xPt);
            gph.DrawString("月份", new Font("宋体", ), Brushes.Black, new PointF(cPt.Y + , cPt.Y + ));
            //画Y轴
            gph.DrawLine(Pens.Black, cPt.X, cPt.Y, cPt.X, cPt.X);
            gph.DrawPolygon(Pens.Black, yPt);
            gph.FillPolygon(new SolidBrush(Color.Black), yPt);
            gph.DrawString("单位(万)", new Font("宋体", ), Brushes.Black, new PointF(, ));
            for (int i = ; i <= ; i++)
            {
                //画Y轴刻度
                if (i < )
                {
                    gph.DrawString((i * ).ToString(), new Font("宋体", ), Brushes.Black, new PointF(cPt.X - , cPt.Y - i *  - ));
                    gph.DrawLine(Pens.Black, cPt.X - , cPt.Y - i * , cPt.X, cPt.Y - i * );
                }
                //画X轴项目
                gph.DrawString(month[i - ].Substring(, ), new Font("宋体", ), Brushes.Black,
                new PointF(cPt.X + i *  - , cPt.Y + ));
                gph.DrawString(month[i - ].Substring(, ), new Font("宋体", ), Brushes.Black,
                new PointF(cPt.X + i *  - , cPt.Y + ));
                if (month[i - ].Length > ) gph.DrawString(month[i - ].Substring(, ), new Font("宋体", ),
                Brushes.Black,
                new PointF(cPt.X + i *  - , cPt.Y + ));
                gph.DrawLine(Pens.Black, cPt.X + i * , cPt.Y, cPt.X + i * , cPt.Y + );
                //画点
                gph.DrawEllipse(Pens.Black, cPt.X + i * , cPt.Y - d[i - ] *  - 1.5F, , );
                gph.FillEllipse(new SolidBrush(Color.Black), cPt.X + i * , cPt.Y - d[i - ] *  - 1.5F,
                , );
                //画数值
                gph.DrawString(d[i - ].ToString(), new Font("宋体", ), Brushes.Black,
                new PointF(cPt.X + i * , cPt.Y - d[i - ] * ));
                //画折线
                if (i > )
                    gph.DrawLine(Pens.Red, cPt.X + (i - ) * , cPt.Y - d[i - ] * , cPt.X + i * , cPt.Y - d[i - ] * );
            }
            pictureBox1.Image = bMap;
        }

    }
}

四：注意事项

如何建立一个有比例关系的坐标系，主要是确定实际距离和像素的关系，一个像素代表多少米的距离

如何生成一个动态比例尺、动态刻度值的坐标系，这就需要确立一个参照点，将这个参照点作为零点，再计算刻度值，从零点的左右两边分别标刻度值。标点时，需要确立动态的像素和距离的关系来确定位置