本文实例主要展示了.Net实现上传图片按比例自动缩小或放大的方法，是非常实用的功能。分享给大家供大家参考之用。具体方法如下：
//// <summary> /// 按比例缩小图片，自动计算宽度 /// </summary> /// <param>源图文件名(包括路径)</param> /// <param>缩小后保存为文件名(包括路径)</param> /// <param>缩小至高度</param> public void SmallPicWidth(string strOldPic, string strNewPic, int intHeight) { System.Drawing.Bitmap objPic, objNewPic; try { objPic = new System.Drawing.Bitmap(strOldPic); int intWidth = (intHeight / objPic.Height) * objPic.Width; objNewPic = new System.Drawing.Bitmap(objPic, intWidth, intHeight); objNewPic.Save(strNewPic); } catch (Exception exp) { throw exp; } finally { objPic = null; objNewPic = null; } } /**//// <summary> /// 缩小图片 /// </summary> /// <param>源图文件名(包括路径)</param> /// <param>缩小后保存为文件名(包括路径)</param> /// <param>缩小至宽度</param> /// <param>缩小至高度</param> public void SmallPic(string strOldPic, string strNewPic, int intWidth, int intHeight) { System.Drawing.Bitmap objPic, objNewPic; try { objPic = new System.Drawing.Bitmap(strOldPic); objNewPic = new System.Drawing.Bitmap(objPic, intWidth, intHeight); objNewPic.Save(strNewPic); } catch (Exception exp) { throw exp; } finally { objPic = null; objNewPic = null; } }