asp.net 等比例 生成 高清图片

private System.Drawing.Image GetImage(string path) { if (path.StartsWith("http")) { System.Net.WebRequest request = System.Net.WebRequest.Create(path); request.Timeout = 10000; System.Net.HttpWebResponse httpresponse = (System.Net.HttpWebResponse)request.GetResponse(); Stream s = httpresponse.GetResponseStream(); return System.Drawing.Image.FromStream(s); } else { return System.Drawing.Image.FromFile(path); } } public void CreateImageOutput(int width, int height, string oPath, string tPath) {Image img = GetImage(oPath); Bitmap originalBmp = null;// new Bitmap(oPath); originalBmp = new Bitmap(img); img.Dispose(); // 源图像在新图像中的位置 int left, top; if (originalBmp.Width <= width && originalBmp.Height <= height) { // 原图像的宽度和高度都小于生成的图片大小 left = (int)Math.Round((decimal)(width - originalBmp.Width) / 2); top = (int)Math.Round((decimal)(height - originalBmp.Height) / 2); // 最终生成的图像 Bitmap bmpOut = new Bitmap(width, height); using (Graphics graphics = Graphics.FromImage(bmpOut)) { // 设置高质量插值法 graphics.InterpolationMode = InterpolationMode.HighQualityBicubic; // 清空画布并以白色背景色填充 graphics.Clear(Color.White); //加上边框 //Pen pen = new Pen(ColorTranslator.FromHtml("#cccccc")); // graphics.DrawRectangle(pen, 0, 0, width - 1, height - 1); // 把源图画到新的画布上 graphics.DrawImage(originalBmp, left, top); } bmpOut.Save(tPath);//保存为文件，tpath 为要保存的路径 //this.OutputImgToPage(bmpOut);//直接输出到页面 bmpOut.Dispose(); originalBmp.Dispose(); return; } // 新图片的宽度和高度，如400*200的图像，想要生成160*120的图且不变形， // 那么生成的图像应该是160*80，然后再把160*80的图像画到160*120的画布上 int newWidth, newHeight; if (width * originalBmp.Height < height * originalBmp.Width) { newWidth = width; newHeight = (int)Math.Round((decimal)originalBmp.Height * width / originalBmp.Width); // 缩放成宽度跟预定义的宽度相同的，即left=0，计算top left = 0; top = (int)Math.Round((decimal)(height - newHeight) / 2); } else { newWidth = (int)Math.Round((decimal)originalBmp.Width * height / originalBmp.Height); newHeight = height; // 缩放成高度跟预定义的高度相同的，即top=0，计算left left = (int)Math.Round((decimal)(width - newWidth) / 2); top = 0; } // 生成按比例缩放的图，如：160*80的图 Bitmap bmpOut2 = new Bitmap(newWidth, newHeight); using (Graphics graphics = Graphics.FromImage(bmpOut2)) { graphics.InterpolationMode = InterpolationMode.HighQualityBicubic; graphics.FillRectangle(Brushes.White, 0, 0, newWidth, newHeight); graphics.DrawImage(originalBmp, 0, 0, newWidth, newHeight); } // 再把该图画到预先定义的宽高的画布上，如160*120 Bitmap lastbmp = new Bitmap(width, height); using (Graphics graphics = Graphics.FromImage(lastbmp)) { // 设置高质量插值法 graphics.InterpolationMode = InterpolationMode.HighQualityBicubic; // 清空画布并以白色背景色填充 graphics.Clear(Color.White); //加上边框 //Pen pen = new Pen(ColorTranslator.FromHtml("#cccccc")); //graphics.DrawRectangle(pen, 0, 0, width - 1, height - 1); // 把源图画到新的画布上 graphics.DrawImage(bmpOut2, left, top); } lastbmp.Save(tPath);//保存为文件，tpath 为要保存的路径 //this.OutputImgToPage(lastbmp);//直接输出到页面 lastbmp.Dispose();originalBmp.Dispose(); } //private void OutputImgToPage(System.Drawing.Bitmap bmp) //{ // //输出到页面 // MemoryStream ms = new MemoryStream(); // bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); // Response.ClearContent(); //需要输出图象信息 要修改HTTP头 // byte[] buffer = ms.ToArray(); // Response.AddHeader("Content-type", "image/jpeg"); // Response.BinaryWrite(buffer); // bmp.Dispose(); //}

 

调用：

s.CreateImageOutput(660, 840, "http://xxx,jpg", Server.MapPath("~/Upload/byyh/Pimg/d/fdsafas.jpg"));