• c#生成缩略图(2)


    cut模式生成,会裁切图片

           /// <summary>
            /// 生成缩略图
            /// </summary>
            /// <param name="originalImagePath">源图路径(物理路径)</param>
            /// <param name="thumbnailPath">缩略图路径(物理路径)</param>
            /// <param name="width">缩略图宽度</param>
            /// <param name="height">缩略图高度</param>
            /// <param name="mode">生成缩略图的方式</param>    
            public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
            {
                Image originalImage = 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;                    
                    default :
                        break;
                }    
                
                //新建一个bmp图片
                Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
    
                //新建一个画板
                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(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 Rectangle(0, 0, towidth, toheight), 
                    new Rectangle(x, y, ow,oh),
                    GraphicsUnit.Pixel);
    
                try
                {            
                    //以jpg格式保存缩略图
                    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                }
                catch(System.Exception e)
                {
                    throw e;
                }
                finally
                {
                    originalImage.Dispose();
                    bitmap.Dispose();                        
                    g.Dispose();
                }
            }
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  • 原文地址:https://www.cnblogs.com/mengxingxinqing/p/3123954.html
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