如何在C#中实现图片缩放

//下面给出三个简单的方法，后面两个方法是扩展，估计有时用得着

//************************************************************//

/// <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;

}

}



/// <summary>

/// 按比例缩小图片，自动计算高度

/// </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="intWidth">缩小至宽度</param>

public void SmallPic(string strOldPic, string strNewPic, int intWidth)

{



System.Drawing.Bitmap objPic,objNewPic;

try

{

objPic = new System.Drawing.Bitmap(strOldPic);

int intHeight=(intWidth / objPic.Width) * objPic.Height;

objNewPic=new System.Drawing.Bitmap(objPic,intWidth,intHeight);

objNewPic.Save(strNewPic);



}

catch(Exception exp){throw exp;}

finally

{

objPic=null;

objNewPic=null;

}

}





/// <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 SmallPic(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;

}

}

 摘自：http://www.alixixi.com/program/a/2008020624216.shtml