本文中来源于网络，仅供参考
/// <summary>
/// 上传图片进行缩放
/// </summary>
/// <param name="fileName">图片绝对地址</param>
/// <param name="destWidth">指定宽度</param>
/// <param name="destHeight">指定高度</param>
/// <param name="type">1--固定缩放；2--按比例缩放；3--指定宽度,宽度大于指定宽度按指定宽度进行等比缩放，小于指定宽度按原图大小上传；4--原图直接上传</param>
public void ReducesPic(string fileName, int destWidth, int destHeight, int type)
{
if (!fileName.Equals(""))
{
//图片决定路径
string Allpath = fileName;
//生成原图
System.IO.Stream stream = System.IO.File.OpenRead(Allpath);
System.Drawing.Image oImage = System.Drawing.Image.FromStream(stream);
stream.Close();
stream.Dispose();
System.Drawing.Image.GetThumbnailImageAbort callb = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
string fileType = fileName.Substring(fileName.LastIndexOf(".") + 1);
int oWidth = oImage.Width;
int oHeight = oImage.Height;
int tWidth = destWidth; //设置缩略图初始宽度
int tHeight = destHeight; //设置缩略图初始高度
//按指定宽高缩放
if (type == 1)
{
tWidth = destWidth;
tHeight = destHeight;
}
//按比例计算出缩略图的宽度和高度
else if (type == 2)
{
if (oWidth > tWidth || oHeight > tHeight)
{
if (oWidth >= oHeight)
{
tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
}
else
{
tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
}
}
else
{
tWidth = oWidth; //原图宽度
tHeight = oHeight; //原图高度
}
}
//指定宽度,宽度大于指定宽度按指定宽度进行等比缩放，小于指定宽度按原图大小上传
else if (type == 3)
{
if (oWidth >= tWidth)
{
if (oWidth >= oHeight)
{
tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
}
else
{
tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
}
}
else
{
tWidth = oWidth; //原图宽度
tHeight = oHeight; //原图高度
}
}
else
{
tWidth = oWidth; //原图宽度
tHeight = oHeight; //原图高度
}
//生成缩略原图
oImage = oImage.GetThumbnailImage(tWidth, tHeight, callb, IntPtr.Zero);
oImage.Save(Allpath);
}
}
public static bool ThumbnailCallback() { return false; }
