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 name="strOldPic">源图文件名(包括路径)</param>/// <param name="strNewPic">缩小后保存为文件名(包括路径)</param>/// <param name="intHeight">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 name="strOldPic">源图文件名(包括路径)</param>/// <param name="strNewPic">缩小后保存为文件名(包括路径)</param>/// <param name="intWidth">缩小至宽度</param>/// <param name="intHeight">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; }}

希望本文所述实例对大家的asp.net程序设计有一定的借鉴价值。