.Net實現(xiàn)上傳圖片按比例自動縮小或放大的方法

//// summary>
/// 按比例縮小圖片，自動計算寬度
/// /summary>
/// param name="strOldPic">源圖文件名(包括路徑)/param>
/// param name="strNewPic">縮小后保存為文件名(包括路徑)/param>
/// param name="intHeight">縮小至高度/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>
/// 縮小圖片
/// /summary>
/// param name="strOldPic">源圖文件名(包括路徑)/param>
/// param name="strNewPic">縮小后保存為文件名(包括路徑)/param>
/// param name="intWidth">縮小至寬度/param>
/// param name="intHeight">縮小至高度/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;
  }
}