winfrom-OpenFileDialog选择图片并设定大小

￡神魔★判官ぃ 2022-07-12 02:41 238阅读 0赞

![SouthEast][]

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);
            }
        }
    }

![SouthEast 1][]

[SouthEast]: /images/20220711/2ac8b1b876ab47ad8cd301395ff0868c.png
[SouthEast 1]: /images/20220711/95099f9b5fa341e890f19ca28642ae26.png