pictureBox画线

最新推荐文章于 2024-04-17 20:02:58 发布

redder_xu

最新推荐文章于 2024-04-17 20:02:58 发布

阅读量1.5k

点赞数

CC 4.0 BY-SA版权

分类专栏： winform 文章标签： object null exception button class

本文链接：https://blog.youkuaiyun.com/redder_xu/article/details/6729660

winform 专栏收录该内容

47 篇文章

订阅专栏

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 WindowsFormsApplication2
{
    public partial class Form4 : Form
    {
        Pen p = null;
        Graphics g = null;
        List<int> x = new List<int>();
        List<int> y = new List<int>();
        SolidBrush b = new SolidBrush(Color.Red);

        public Form4()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                OpenFileDialog openfileDialog = new OpenFileDialog();
                //openfileDialog.Filter = "GIF图片(*.gif)|*.gif|JPG图片(*.jpg)|*.jpg|BMP图片(*.bmp)|*.bmp|PNG图片(*.png)|*.png|所有图片文件(*.gif,*.jpg,*.bmp,*.png)|*.gif;*.jpg;*.bmp;*.png";
                if ((openfileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK))
                {
                    this.pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
                    this.pictureBox1.ImageLocation = openfileDialog.FileName;
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString(), "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);

}
}

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                g.FillRectangle(b, e.X, e.Y, 2, 2);
                if (x.Count > 0 || y.Count > 0)
                {
                    x.Clear();
                    y.Clear();
                }
                x.Add(e.X);
                y.Add(e.Y);
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                g.FillRectangle(b,e.X,e.Y,2,2);
                x.Add(e.X);
                y.Add(e.Y);
                if (x.Count > 1 || y.Count > 1)
                {
                    g.DrawLine(p,x[x.Count-2],y[y.Count-2],x[x.Count-1],y[y.Count-1]);
                }
            }
        }

        private void Form4_Load(object sender, EventArgs e)
        {
            if (p == null)
            {
                p = new Pen(Color.Red, 0.5f);
            }
            if(g==null)
            {
                g=this.pictureBox1.CreateGraphics();
            }

}
}
}