winfrom-OpenFileDialog选择图片并设定大小

using System;using System.Drawing;using System.Windows.Forms;namespace WindowsFormsapplication2{    public partial class selectimg : Form    {        public selectimg()        {            InitializeComponent();            this.pictureBox1.BorderStyle = BorderStyle.FixedSingle;            this.openFileDialog1.Filter = "图片|*.jpg;*.png";        }        PRivate void button1_Click(object sender, EventArgs e)        {            if (openFileDialog1.ShowDialog() == DialogResult.OK)            {                Image fromImage = Image.FromFile(this.openFileDialog1.FileName);                fromImage = fromImage.AdjImageToFitSize(pictureBox1.Width, pictureBox1.Height); //350                this.pictureBox1.Image = fromImage;            }        }        //...    }    internal static class ImgHelp    {        /// <summary>        /// 获取等比例缩放的图片（高宽不一致时获取最中间部分的图片）        /// </summary>        public static Image AdjImageToFitSize(this Image fromImage, int width, int height)        {            Bitmap bitmap = new Bitmap(width, height);            Graphics graphics = Graphics.FromImage(bitmap);            Point[] destPoints = new Point[] {                new Point(0, 0),                new Point(width, 0),                new Point(0, height)            };            Rectangle rect = GetImageRectangle(fromImage.Width, fromImage.Height);            graphics.DrawImage(fromImage, destPoints, rect, GraphicsUnit.Pixel);            Image image = Image.FromHbitmap(bitmap.GetHbitmap());            bitmap.Dispose();            graphics.Dispose();            return image;        }        /// <summary>        /// 居中位置获取        /// </summary>        private static Rectangle GetImageRectangle(int w, int h)        {            int x = 0;            int y = 0;            if (h > w)            {                h = w;                y = (h - w) / 2;            }            else            {                w = h;                x = (w - h) / 2;            }            return new Rectangle(x, y, w, h);        }    }}