C#压缩图片，可以指定图片模板高宽

今天要在web程序处理图片，指定图片的高宽大小。google了一把资料。觉得此方法挺不错的，大家可以借鉴一下，如果小弟写的有不对的地方请大家指点一下：以下代码在winform写的，在web下测试可以使用。

//生成缩略图函数

        //顺序参数：源图文件流、缩略图存放地址、模版宽、模版高

        //注：缩略图大小控制在模版区域内

        public static void MakeSmallImg(System.IO.Stream fromFileStream, string fileSaveUrl, System.Double templateWidth, System.Double templateHeight)

        {

            //从文件取得图片对象，并使用流中嵌入的颜色管理信息

            System.Drawing.Image myImage = System.Drawing.Image.FromStream(fromFileStream, true);

            //缩略图宽、高

            System.Double newWidth = myImage.Width, newHeight = myImage.Height;

            //宽大于模版的横图

            if (myImage.Width > myImage.Height || myImage.Width == myImage.Height)

            {

                if (myImage.Width > templateWidth)

                {

                    //宽按模版，高按比例缩放

                    newWidth = templateWidth;

                    newHeight = myImage.Height * (newWidth / myImage.Width);

                }

            }

            //高大于模版的竖图

            else

            {

                if (myImage.Height > templateHeight)

                {

                    //高按模版，宽按比例缩放

                    newHeight = templateHeight;

                    newWidth = myImage.Width * (newHeight / myImage.Height);

                }

            }

            //取得图片大小

            System.Drawing.Size mySize = new Size((int)newWidth, (int)newHeight);

            //新建一个bmp图片

            System.Drawing.Image bitmap = new System.Drawing.Bitmap(mySize.Width, mySize.Height);

            //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;

            //清空一下画布

            g.Clear(Color.White);

            //在指定位置画图

            g.DrawImage(myImage, new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height),

            new System.Drawing.Rectangle(0, 0, myImage.Width, myImage.Height),

            System.Drawing.GraphicsUnit.Pixel);

            ///文字水印

            //System.Drawing.Graphics G=System.Drawing.Graphics.FromImage(bitmap);

            //System.Drawing.Font f=new Font("宋体",10);

            //System.Drawing.Brush b=new SolidBrush(Color.Black);

            //G.DrawString("myohmine",f,b,10,10);

            //G.Dispose();

            ///图片水印

            //System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath("pic/1.gif"));

            //Graphics a = Graphics.FromImage(bitmap);

            //a.DrawImage(copyImage, new Rectangle(bitmap.Width-copyImage.Width,bitmap.Height-copyImage.Height,copyImage.Width, copyImage.Height),0,0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);

            //copyImage.Dispose();

            //a.Dispose();

            //copyImage.Dispose();

            //保存缩略图

            bitmap.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

            g.Dispose();

            myImage.Dispose();

            bitmap.Dispose();

        }

 

 private void button2_Click(object sender, EventArgs e)

        {

            OpenFileDialog fileDialog = new OpenFileDialog();

            fileDialog.Title = "选择图片文件";

           // fileDialog.Filter = "excel files (*.xls)|*.xls";

            fileDialog.FilterIndex = 1;

            if (fileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)

            {



                System.IO.FileStream file =System.IO.File.Open(fileDialog.FileName,System.IO.FileMode.Open);

                System.IO.Stream strea = file;

                file.Close();

                MakeSmallImg(strea, "缩略图.jpg", 150, 150);

              //  file.Close();

              

            }

        }