画图的问题

Question

我这样怎么不显示图出来？
public Form1()
        {
            InitializeComponent();
            Pen pen = new Pen(Color.Red);
            pen.Width = 5;
            //Graphics gr = this.CreateGraphics();
            this.CreateGraphics().DrawEllipse(new Pen(Color.Red), 125 - 5, 130 - 5, 2 * 5, 2 * 5);
        }

Answer 1

下面两种方法可以任选一种试试看
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;namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            
            //方法1
            Bitmap img = new Bitmap(this.Width, this.Height);
            Graphics g = Graphics.FromImage(img);
            Pen pen = new Pen(Color.Red);
            pen.Width = 5;            
            g.DrawEllipse(new Pen(Color.Red), 125 - 5, 130 - 5, 2 * 5, 2 * 5);
            this.BackgroundImage = img;
        }        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            //方法2
            Pen pen = new Pen(Color.Red);
            pen.Width = 5;
            //Graphics gr = this.CreateGraphics(); 
            this.CreateGraphics().DrawEllipse(new Pen(Color.Red), 125 - 5, 130 - 5, 2 * 5, 2 * 5);         }
    }
}

Answer 2

下面的只有按钮可以画出来！·
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;namespace DeviceApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            aa();
        }        private void button1_Click(object sender, EventArgs e)
        {
            aa();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            aa();
        }
        void aa() {
            Pen pen = new Pen(Color.Red);
            pen.Width = 5;
            //Graphics gr = this.CreateGraphics();
            this.CreateGraphics().DrawEllipse(new Pen(Color.Red), 125 - 5, 130 - 5, 2 * 5, 2 * 5);
        }
    }
}

Answer 3

呵呵 方法1不错~~画BITMAP里~~ 然后显示到背景~~学习了:)

Answer 4

    private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Pen pen = new Pen(Color.Red);
            pen.Width = 5;
            //Graphics gr = this.CreateGraphics(); 
            this.CreateGraphics().DrawEllipse(new Pen(Color.Red), 125 - 5, 130 - 5, 2 * 5, 2 * 5);         }