保持清晰度的图片像素比例缩放方法

 /// <summary>
        /// 按比例进行图片缩放，不失真
        /// </summary>
        /// <param name="srcbitmap"></param>
        /// <param name="multiple"></param>
        /// <returns></returns>
        public static Bitmap Magnifier(Bitmap srcbitmap, double multiple)
        {
            Bitmap bitmap = new Bitmap((int)(srcbitmap.Size.Width * multiple), (int)(srcbitmap.Size.Height * multiple));
            BitmapData srcbitmapdata = srcbitmap.LockBits(new Rectangle(new Point(0, 0), srcbitmap.Size), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
            BitmapData bitmapdata = bitmap.LockBits(new Rectangle(new Point(0, 0), bitmap.Size), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
            unsafe
            {
                byte* srcbyte = (byte*)(srcbitmapdata.Scan0.ToPointer());
                byte* sourcebyte = (byte*)(bitmapdata.Scan0.ToPointer());
                for (int y = 0; y < bitmapdata.Height; y++)
                {
                    for (int x = 0; x < bitmapdata.Width; x++)
                    {
                        long index = ((int)(x / multiple)) * 4 + ((int)(y / multiple)) * srcbitmapdata.Stride;
                        sourcebyte[0] = srcbyte[index];
                        sourcebyte[1] = srcbyte[index + 1];
                        sourcebyte[2] = srcbyte[index + 2];
                        sourcebyte[3] = srcbyte[index + 3];
                        sourcebyte += 4;
                    }
                }
            }
            srcbitmap.UnlockBits(srcbitmapdata);
            bitmap.UnlockBits(bitmapdata);