C# 按比例变化图片尺寸

参数times为小数则图片为放大，如times=0.5,则图片放大两倍

/// <summary>
/// 按比例变化图片尺寸
/// </summary>
/// <param name="bm">原图</param>
/// <param name="times">变化倍数</param>
/// <returns></returns>
public static Bitmap ZoomPicture(Bitmap bm, double times)
{
    int nowWidth = (int)(bm.Width / times);
    int nowHeight = (int)(bm.Height / times);
    Bitmap newbm = new Bitmap(nowWidth, nowHeight);
    if (times >= 1 && times <= 1.1)
    {
        newbm = bm;
    }
    else
    {
        Graphics g = Graphics.FromImage(newbm);
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.SmoothingMode = SmoothingMode.HighQuality;
        g.CompositingQuality = CompositingQuality.HighQuality;
        g.DrawImage(bm, new Rectangle(0, 0, nowWidth, nowHeight), new Rectangle(0, 0, bm.Width, bm.Height), GraphicsUnit.Pixel);
        g.Dispose();
    }
    return newbm;
}