[转载]C#生成缩略图,加文字或图片水印 – 范涛 – 博客园.
最近做东西,客户要求上传商品大图,自动生成缩略图,要求等比缩放,正好能在指定的大小内显示,(即如果高超出的比宽超出的多,就把高缩到指定高度,宽也等比缩放,反之宽也如此)
从网上找了如下代码(出处不明),但发现他的生成缩略图的方式有四种,但都不是我想要的,于是在上面加了case “DB”://等比缩放(不变形,如果高大按高,宽大按宽缩放) 这种方式实现了我想要的功能
/**/ /// /// 生成缩略图 /// ///源图路径(物理路径) ///缩略图路径(物理路径) ///缩略图宽度 ///缩略图高度 ///生成缩略图的方式 public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode,string type) { System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath); int towidth = width; int toheight = height; int x = 0; int y = 0; int ow = originalImage.Width; int oh = originalImage.Height; switch (mode) { case "HW"://指定高宽缩放(可能变形) break; case "W"://指定宽,高按比例 toheight = originalImage.Height * width / originalImage.Width; break; case "H"://指定高,宽按比例 towidth = originalImage.Width * height / originalImage.Height; break; case "Cut"://指定高宽裁减(不变形) if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) { oh = originalImage.Height; ow = originalImage.Height * towidth / toheight; y = 0; x = (originalImage.Width - ow) / 2; } else { ow = originalImage.Width; oh = originalImage.Width * height / towidth; x = 0; y = (originalImage.Height - oh) / 2; } break; case "DB"://等比缩放(不变形,如果高大按高,宽大按宽缩放) if ((double)originalImage.Width / (double)towidth < (double)originalImage.Height / (double)toheight) { toheight = height; towidth = originalImage.Width * height / originalImage.Height; } else { towidth = width; toheight = originalImage.Height * width / originalImage.Width; } break; default: break; } //新建一个bmp图片 System.Drawing.Image bitmap = 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), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel); try { //保存缩略图 if (type=="JPG") { bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); } if (type=="BMP") { bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp); } if (type=="GIF") { bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif); } if (type=="PNG") { bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png); } } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } } /**/ /// /// 在图片上增加文字水印 /// ///原服务器图片路径 ///生成的带文字水印的图片路径 protected void AddShuiYinWord(string Path, string Path_sy) { string addText = "测试水印"; System.Drawing.Image image = System.Drawing.Image.FromFile(Path); System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image); g.DrawImage(image, 0, 0, image.Width, image.Height); System.Drawing.Font f = new System.Drawing.Font("Verdana", 16); System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue); g.DrawString(addText, f, b, 15, 15); g.Dispose(); image.Save(Path_sy); image.Dispose(); } /**/ /// /// 在图片上生成图片水印 /// ///原服务器图片路径 ///生成的带图片水印的图片路径 ///水印图片路径 protected void AddShuiYinPic(string Path, string Path_syp, string Path_sypf) { System.Drawing.Image image = System.Drawing.Image.FromFile(Path); System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Path_sypf); System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image); g.DrawImage(copyImage, new System.Drawing.Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, System.Drawing.GraphicsUnit.Pixel); g.Dispose(); image.Save(Path_syp); image.Dispose(); }