GDI+畫圖類Graphics的使用

一：基礎定義

 #region 定義線尾、線頭爲箭頭、字體和筆刷
                Pen p = new Pen(Color.Black, 1);//定義畫筆 藍色，寬度爲1（座標顯示顏色）
                p.EndCap = LineCap.ArrowAnchor;//定義線尾的樣式爲箭頭

                Pen pk = new Pen(Color.Black, 1);//定義畫筆 黑色，寬度爲1（座標顯示顏色）
                Pen pbl = new Pen(Color.Red,1);
                pbl.EndCap = LineCap.ArrowAnchor;//定義線尾的樣式爲箭頭

                StringFormat strF = new StringFormat(StringFormatFlags.DirectionVertical);//定義格式
                Font f = new System.Drawing.Font("宋體", 10);//定義字體
                SolidBrush bB = new SolidBrush(Color.Black);//定義單色畫刷
                SolidBrush bl = new SolidBrush(Color.Red);//定義單色畫刷
            #endregion

二：使用前準備，新建一個picturebox，實例化一個 Graphics類，關聯它們

 Graphics gph;//繪畫區域
 Bitmap bmp = new Bitmap(pic_Img.Width, pic_Img.Height);//600, 512
                gph = Graphics.FromImage(bmp);

三：實例

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 定義線尾、線頭爲箭頭、字體和筆刷
            Pen p = new Pen(Color.Blue, 1);//定義畫筆 藍色，寬度爲1（座標顯示顏色）
            p.EndCap = LineCap.ArrowAnchor;//定義線尾的樣式爲箭頭
            p.StartCap = LineCap.ArrowAnchor;//定義線首的樣式爲箭頭

            Font f = new System.Drawing.Font("宋體", 10);//定義字體
            SolidBrush bB = new SolidBrush(Color.Black);//定義單色畫刷
            //SolidBrush bB = new SolidBrush(Color.Blue);
            #endregion
            string[] month = new string[12] { "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[12] { 20.5F, 60, 10.8F, 15.6F, 30, 70.9F, 50.3F, 30.7F, 70, 50.4F, 30.8F, 20 };
            //畫圖初始化
            Bitmap bMap = new Bitmap(526, 500);
            Graphics gph = Graphics.FromImage(bMap);
            //gph.Clear(Color.White);
            PointF cPt = new PointF(40, 420);//中心點
            PointF[] xPt = new PointF[3]{new PointF(cPt.Y+15,cPt.Y),
new PointF(cPt.Y,cPt.Y-8),new PointF(cPt.Y,cPt.Y+8)};//X軸三角形
            PointF[] yPt = new PointF[3]{new PointF(cPt.X,cPt.X-15),
new PointF(cPt.X-8,cPt.X),new PointF(cPt.X+8,cPt.X)};//Y軸三角形
            gph.DrawString("紅馬車公司月生產量圖表", new Font("宋體", 14)
            , Brushes.Black, new PointF(cPt.X + 60, cPt.X));//圖標標題
            //畫X軸
            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("宋體", 12), Brushes.Black, new PointF(cPt.Y + 10, cPt.Y + 10));
            //畫Y軸
            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("單位(萬)", new Font("宋體", 12), Brushes.Black, new PointF(0, 7));
            for (int i = 1; i <= 12; i++)
            {
                //畫Y軸刻度
                if (i < 11)
                {
                    gph.DrawString((i * 10).ToString(), new Font("宋體", 11), Brushes.Black, new PointF(cPt.X - 30, cPt.Y - i * 30 - 6));
                    gph.DrawLine(Pens.Black, cPt.X - 3, cPt.Y - i * 30, cPt.X, cPt.Y - i * 30);
                }
                //畫X軸項目
                gph.DrawString(month[i - 1].Substring(0, 1), new Font("宋體", 11), Brushes.Black,
                new PointF(cPt.X + i * 30 - 5, cPt.Y + 5));
                gph.DrawString(month[i - 1].Substring(1, 1), new Font("宋體", 11), Brushes.Black,
                new PointF(cPt.X + i * 30 - 5, cPt.Y + 20));
                if (month[i - 1].Length > 2) gph.DrawString(month[i - 1].Substring(2, 1), new Font("宋體", 11),
                Brushes.Black,
                new PointF(cPt.X + i * 30 - 5, cPt.Y + 35));
                gph.DrawLine(Pens.Black, cPt.X + i * 30, cPt.Y, cPt.X + i * 30, cPt.Y + 3);
                //畫點
                gph.DrawEllipse(Pens.Black, cPt.X + i * 30, cPt.Y - d[i - 1] * 3 - 1.5F, 3, 3);
                gph.FillEllipse(new SolidBrush(Color.Black), cPt.X + i * 30, cPt.Y - d[i - 1] * 3 - 1.5F,
                3, 3);
                //畫數值
                gph.DrawString(d[i - 1].ToString(), new Font("宋體", 11), Brushes.Black,
                new PointF(cPt.X + i * 30, cPt.Y - d[i - 1] * 3));
                //畫折線
                if (i > 1)
                    gph.DrawLine(Pens.Red, cPt.X + (i - 1) * 30, cPt.Y - d[i - 2] * 3, cPt.X + i * 30, cPt.Y - d[i - 1] * 3);
            }
            pictureBox1.Image = bMap;
        }
       
    }
}

 四：注意事項

如何建立一個有比例關係的座標系，主要是確定實際距離和像素的關係，一個像素代表多少米的距離

如何生成一個動態比例尺、動態刻度值的座標系，這就需要確立一個參照點，將這個參照點作爲零點，再計算刻度值，從零點的左右兩邊分別標刻度值。標點時，需要確立動態的像素和距離的關係來確定位置