[C#]ImageResize

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace ImageSize
{   
    public partial class Form1 : Form
    {
        Bitmap bitmapOri = null;
 
        public Form1()
        {
            InitializeComponent();
 
            this.label1.Text = this.trackBar1.Value + "%";
            this.pictureBox1.Image = bitmapOri = Properties.Resources._9996A8335B53615E1E;
        }
 
        private void trackBar1_Scroll(object sender, EventArgs e)
        {
            this.label1.Text = this.trackBar1.Value + "%";
            this.pictureBox1.Image = ResizeImage();
        }
 
        private Bitmap ResizeImage()
        {
            int width  = (bitmapOri.Width  * this.trackBar1.Value) / 100;
            int height = (bitmapOri.Height * this.trackBar1.Value) / 100;
 
            Rectangle rect = new Rectangle(0, 0, width, height);
 
            Bitmap bitmap = new Bitmap(width, height);
            bitmap.SetResolution(bitmapOri.HorizontalResolution, bitmap.VerticalResolution);
 
            using (var g = Graphics.FromImage(bitmap))
            {
                g.CompositingMode = CompositingMode.SourceCopy;
                g.CompositingQuality = CompositingQuality.HighQuality;
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.PixelOffsetMode = PixelOffsetMode.HighQuality;
 
                using (var wrapmode = new ImageAttributes())
                {
                    wrapmode.SetWrapMode(WrapMode.TileFlipXY);
                    g.DrawImage(bitmapOri, rect, 0, 0, bitmapOri.Width, bitmapOri.Height, GraphicsUnit.Pixel, wrapmode);
                }
            }
 
            return bitmap;
        }
    }
}
 

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