Form_load事件处理程序的问题???? [英] Problem with Form_load event handler ????

问题描述

 

我写了以下代码：

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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Pen mypen = new Pen(Color.Black, 1);

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            g.Clip = new Region(new Rectangle(0, 0, 1280, 800));


            g.DrawLine(mypen, 0, 0, 1280, 800);
            
            
        }
    }
}

推荐答案

button.click事件是否连接到处理程序？

Is the button.click event connected to the handler?

最好在Paint事件中绘制：

Its better to draw in the Paint-event:

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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private bool _drawLine = false;

        public Form1()
        {
            InitializeComponent();

            this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);
            this.button1.Click += new System.EventHandler(this.button1_Click);
        }


        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            if(_drawLine)
                e.Graphics.DrawLine(Pens.Black, 0, 0, 1280, 800);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            _drawLine = true;
            this.Invalidate();
        }
    }
}

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