在 C# 中使用纵横比调整图像大小并裁剪中心图像，因此没有间隙

Question

I'm trying to resize user uploaded images to a landscape dimensions eg 450w and 250h while maintaining aspect ratio, but to avoid resized images like portrait images having gaps on the side I would like to crop the centre of the image to fill the resized dimensions.

I have found plenty of code to resize images while maintaining aspect ratio but not what I am looking for above, I'm hoping someone can help.

Answer 1

You should pass needToFill = true:

public static System.Drawing.Image FixedSize(Image image, int Width, int Height, bool needToFill)
{
    #region calculations
    int sourceWidth = image.Width;
    int sourceHeight = image.Height;
    int sourceX = 0;
    int sourceY = 0;
    double destX = 0;
    double destY = 0;

    double nScale = 0;
    double nScaleW = 0;
    double nScaleH = 0;

    nScaleW = ((double)Width / (double)sourceWidth);
    nScaleH = ((double)Height / (double)sourceHeight);
    if (!needToFill)
    {
        nScale = Math.Min(nScaleH, nScaleW);
    }
    else
    {
        nScale = Math.Max(nScaleH, nScaleW);
        destY = (Height - sourceHeight * nScale) / 2;
        destX = (Width - sourceWidth * nScale) / 2;
    }

    if (nScale > 1)
        nScale = 1;

    int destWidth = (int)Math.Round(sourceWidth * nScale);
    int destHeight = (int)Math.Round(sourceHeight * nScale);
    #endregion

    System.Drawing.Bitmap bmPhoto = null;
    try
    {
        bmPhoto = new System.Drawing.Bitmap(destWidth + (int)Math.Round(2 * destX), destHeight + (int)Math.Round(2 * destY));
    }
    catch (Exception ex)
    {
        throw new ApplicationException(string.Format("destWidth:{0}, destX:{1}, destHeight:{2}, desxtY:{3}, Width:{4}, Height:{5}",
            destWidth, destX, destHeight, destY, Width, Height), ex);
    }
    using (System.Drawing.Graphics grPhoto = System.Drawing.Graphics.FromImage(bmPhoto))
    {
        grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
        grPhoto.CompositingQuality = CompositingQuality.HighQuality;
        grPhoto.SmoothingMode = SmoothingMode.HighQuality;

        Rectangle to =  new System.Drawing.Rectangle((int)Math.Round(destX), (int)Math.Round(destY), destWidth, destHeight);
        Rectangle from = new System.Drawing.Rectangle(sourceX, sourceY, sourceWidth, sourceHeight);
        //Console.WriteLine("From: " + from.ToString());
        //Console.WriteLine("To: " + to.ToString());
        grPhoto.DrawImage(image, to, from, System.Drawing.GraphicsUnit.Pixel);

        return bmPhoto;
    }
}