C# 计算图片最大缩放宽高的函数

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/// <summary>         /// 计算同比缩放的值         /// </summary>         /// <param name="oW">原宽</param>         /// <param name="oH">原高</param>         /// <param name="w">目标宽</param>         /// <param name="h">目标高</param>         /// <param name="mode">HW(指定高宽缩放（可能变形）),W(指定宽，高按比例),H(指定高，宽按比例),MaxHW(最大宽高比例缩放，比如原100*50->50*30，则结果是50*25)</param>         /// <returns></returns>         public static WidthHeight TBScale(double oW,double oH,double w,double h,string mode= "W")         {             WidthHeight wh = new WidthHeight();             double ow = wh.width = oW;             double oh = wh.height = oH;               switch (mode)             {                 case "HW":  //指定高宽缩放（可能变形）                      wh.width = (int)w;                     wh.height = (int)h;                     break;                 case "W":   //指定宽，高按比例                                        wh.height = oH * w / oW;                     break;                 case "H":   //指定高，宽按比例                     wh.width = oW * h / oH;                     break;                 case "Cut": //指定高宽裁减（不变形）                                    if ((double)oW / (double)oH > (double)wh.width / (double)wh.height)                     {                         oh = oH;                         ow = oH * wh.width / wh.height;                     }                     else                     {                         ow = oW;                         oh = oW * h / wh.width;                     }                     break;                 case "MaxHW"://最大宽高比例缩放，比如原100*50->50*30，则结果是50*25                     var rmaxhw_d1w = oW * 1.0 / w;                     var rmaxhw_d2h = oH * 1.0 / h;                     if (rmaxhw_d1w > rmaxhw_d2h)                     {                         if (rmaxhw_d1w <= 1)                         {                             wh.width = oW; h = oH;                             goto case "HW";                         }                         wh.width = w;                         goto case "W";                     }                     if (rmaxhw_d2h <= 1)                     {                         wh.width = oW; h = oH;                         goto case "HW";                     }                     wh.height = h;                     goto case "H";                 default:                     break;             }             wh.width = (int)wh.width;             wh.height = (int)wh.height;             return wh;         }     }

　　

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/// <summary>     /// 宽高类     /// </summary>     public class WidthHeight     {         /// <summary>         /// 宽         /// </summary>         public double width { get; set; }         /// <summary>         /// 高         /// </summary>         public double height { get; set; }     }