C#打开、保存图像

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

        //文件名
        private string curFileName;
        //图像对象
        private System.Drawing.Bitmap curBitmap;


        //打开图像文件
        private void 打开图像ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog opnDlg = new OpenFileDialog();
            opnDlg.Filter = "所有图像文件 | *.bmp; *.pcx; *.png; *.jpg; *.gif;" +
                "*.tif; *.ico; *.dxf; *.cgm; *.cdr; *.wmf; *.eps; *.emf|" +
                "位图( *.bmp; *.jpg; *.png;...) | *.bmp; *.pcx; *.png; *.jpg; *.gif; *.tif; *.ico|" +
                "矢量图( *.wmf; *.eps; *.emf;...) | *.dxf; *.cgm; *.cdr; *.wmf; *.eps; *.emf";
            opnDlg.Title = "打开图像文件";
            opnDlg.ShowHelp = true;
            if (opnDlg.ShowDialog() == DialogResult.OK)
            {
                curFileName = opnDlg.FileName;
                try
                {
                    curBitmap = (Bitmap)Image.FromFile(curFileName);
                }
                catch (Exception exp)
                {
                    MessageBox.Show(exp.Message);
                }
            }
            //对窗体进行重新绘制，这将强制执行paint事件处理程序
            Invalidate();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            //使用窗体的Paint事件的PaintEventArgs属性来获取一个与窗体相关联的Graphic对象。
            Graphics g = e.Graphics;
            if (curBitmap != null)
            {
                //使用DrawImage的方法绘制图像
                //160,20 :显示在主窗体内，图像左上角的坐标
                //curBitmap.Width, curBitmap.Height图像的宽度和高度
                g.DrawImage(curBitmap, 160, 20, curBitmap.Width, curBitmap.Height);
            }
        }

        private void 保存图像ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (curBitmap == null)
            {
                return;
            }
            SaveFileDialog saveDlg = new SaveFileDialog();
            saveDlg.Title = "保存为";
            saveDlg.OverwritePrompt = true;
            saveDlg.Filter =
                "BMP文件 (*.bmp) | *.bmp|" +
                "Gif文件 (*.gif) | *.gif|" +
                "JPEG文件 (*.jpg) | *.jpg|" +
                "PNG文件 (*.png) | *.png";
            saveDlg.ShowHelp = true;
            if (saveDlg.ShowDialog() == DialogResult.OK)
            {
                string fileName = saveDlg.FileName;
                string strFilExtn = fileName.Remove(0, fileName.Length - 3);
                switch (strFilExtn)
                {
                    case "bmp":
                        curBitmap.Save(fileName, System.Drawing.Imaging.ImageFormat.Bmp);
                        break;
                    case "jpg":
                        curBitmap.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);
                        break;
                    case "gif":
                        curBitmap.Save(fileName, System.Drawing.Imaging.ImageFormat.Gif);
                        break;
                    case "tif":
                        curBitmap.Save(fileName, System.Drawing.Imaging.ImageFormat.Tiff);
                        break;
                    case "png":
                        curBitmap.Save(fileName, System.Drawing.Imaging.ImageFormat.Png);
                        break;
                    default:
                        break;
                }
            }
        }

        private void 关闭ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}