.net缩略图 GDI+一般性错误解决方法。

public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)
{
Graphics draw = null;
string FileExt = "";

System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

int towidth = width;
int toheight = height;

int ow = originalImage.Width;
int oh = originalImage.Height;

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
g.Clear(System.Drawing.Color.Transparent);

//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight));

try
{
//以jpg格式保存缩略图
FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
draw = Graphics.FromImage(bitmap2);
draw.DrawImage(bitmap, 0, 0);

}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
}
}

直接拷贝方法既可用 因为如果只创建一个img对象进行图片的缩略保存会照成锁死。

所以这里申明了2个

System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);