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

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

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            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 };
            //画图初始化
            //在内存中创建一个位图
            Bitmap bMap = new Bitmap(500, 500);
            //根据内存中的位图，创建一个画布，采用这种方式创建的画布效果更好，图形更流畅
            Graphics gph = Graphics.FromImage(bMap);
            //使用白色清空画布，即用白色覆盖画布上的其它内容，以达到清空目的
            gph.Clear(Color.White);
            PointF cPt = new PointF(40, 420);//要绘制图形的中心点
            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轴三角形
            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轴三角形
            gph.DrawString("某工厂某产品月生产量图表", new Font("宋体", 14), Brushes.Black, new PointF(cPt.X + 60, cPt.X));//图表标题
            //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", 12), Brushes.Black, new PointF(cPt.Y + 10, cPt.Y + 10));
            //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", 12), Brushes.Black, new PointF(0, 7));
            //for语句用来绘制12个月的折线
            for (int i = 1; i <= 12; i++)
            {
                //画Y轴刻度
                if (i < 11)
                {
                    gph.DrawString((i * 10).ToString(), new Font("宋体", 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);
                }
                //画X轴项目
                gph.DrawString(month[i - 1].Substring(0, 1), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30 - 5, cPt.Y + 5));
                gph.DrawString(month[i - 1].Substring(1, 1), new Font("宋体", 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("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30 - 5, cPt.Y + 35));
                //画点
                gph.DrawEllipse(Pens.Black, cPt.X + i * 30 - 1.5F, cPt.Y - d[i - 1] * 3 - 1.5F, 3, 3);
                gph.FillEllipse(new SolidBrush(Color.Black), cPt.X + i * 30 - 1.5F, cPt.Y - d[i - 1] * 3 - 1.5F, 3, 3);
                //画数值
                gph.DrawString(d[i - 1].ToString(), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30, cPt.Y - d[i - 1] * 3));
                //画折线
                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;
        }
    }
}