netcore 图片缩略图 - chester·chen

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/// <param name="name"> 文件名 </param> /// <returns> 返回小写后缀，不带“.” </returns> public static string GetFileExt( string name) return name.Split( " . " ).Last().ToLower(); /// <summary> /// 是否为图片文件 /// </summary> /// <param name="fileExt"> 文件扩展名，不含“.” </param> public static bool IsImage( string fileExt) ArrayList al = new ArrayList { " bmp " , " jpeg " , " jpg " , " gif " , " png " , " ico " }; return al.Contains(fileExt); /// <summary> /// 检查是否允许文件 /// </summary> /// <param name="fileExt"> 文件后缀 </param> /// <param name="allowExt"> 允许文件数组 </param> public static bool CheckFileExt( string fileExt, string [] allowExt) return allowExt.Any(t => t == fileExt); /// <summary> /// 制作缩略图 /// </summary> /// <param name="original"> 图片对象 </param> /// <param name="newFileName"> 新图路径 </param> /// <param name="maxWidth"> 最大宽度 </param> /// <param name="maxHeight"> 最大高度 </param> public static void ThumbImg(Image original, string newFileName, int maxWidth, int maxHeight) Size newSize = ResizeImage(original.Width, original.Height, maxWidth, maxHeight); using (Image displayImage = new Bitmap(original, newSize)) displayImage.Save(newFileName, original.RawFormat); finally original.Dispose(); /// <summary> /// 制作缩略图 /// </summary> /// <param name="fileName"> 文件名 </param> /// <param name="newFileName"> 新图路径 </param> /// <param name="maxWidth"> 最大宽度 </param> /// <param name="maxHeight"> 最大高度 </param> public static void ThumbImg( string fileName, string newFileName, int maxWidth, int maxHeight) byte [] imageBytes = File.ReadAllBytes(fileName); Image img = Image.FromStream( new MemoryStream(imageBytes)); ThumbImg(img, newFileName, maxWidth, maxHeight); /// <summary> /// 计算新尺寸 /// </summary> /// <param name="width"> 原始宽度 </param> /// <param name="height"> 原始高度 </param> /// <param name="maxWidth"> 最大新宽度 </param> /// <param name="maxHeight"> 最大新高度 </param> /// <returns></returns> private static Size ResizeImage( int width, int height, int maxWidth, int maxHeight) if (maxWidth <= 0 ) maxWidth = width; if (maxHeight <= 0 ) maxHeight = height; decimal MAX_WIDTH = maxWidth; decimal MAX_HEIGHT = maxHeight; decimal ASPECT_RATIO = MAX_WIDTH / MAX_HEIGHT; int newWidth, newHeight; decimal originalWidth = width; decimal originalHeight = height; if (originalWidth > MAX_WIDTH || originalHeight > MAX_HEIGHT) decimal factor; if (originalWidth / originalHeight > ASPECT_RATIO) factor = originalWidth / MAX_WIDTH; newWidth = Convert.ToInt32(originalWidth / factor); newHeight = Convert.ToInt32(originalHeight / factor); factor = originalHeight / MAX_HEIGHT; newWidth = Convert.ToInt32(originalWidth / factor); newHeight = Convert.ToInt32(originalHeight / factor); newWidth = width; newHeight = height; return new Size(newWidth, newHeight); /// <summary> /// 得到图片格式 /// </summary> /// <param name="name"> 文件名称 </param> /// <returns></returns> public static ImageFormat GetFormat( string name) string ext = GetFileExt(name); switch (ext) case " ico " : return ImageFormat.Icon; case " bmp " : return ImageFormat.Bmp; case " png " : return ImageFormat.Png; case " gif " : return ImageFormat.Gif; default : return ImageFormat.Jpeg;

2019-05-09 10:27:01,330 线程ID:[80] 日志级别：ERROR 出错类：WebApp.HttpGlobalExceptionFilter property:[(null)] - 错误描述：System.TypeInitializationException: The type initializer for 'System.DrawingCore.GDIPlus' threw an exception. ---> System.DllNotFoundException: Unable to load shared library 'gdiplus' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: libgdiplus: cannot open shared object file: No such file or directory
   at System.DrawingCore.GDIPlus.GdiplusStartup(UInt64& token, GdiplusStartupInput& input, GdiplusStartupOutput& output)
   at System.DrawingCore.GDIPlus..cctor()
   --- End of inner exception stack trace ---
   at System.DrawingCore.GDIPlus.GdipGetGenericFontFamilySansSerif(IntPtr& fontFamily)
   at System.DrawingCore.FontFamily..ctor(GenericFontFamilies genericFamily)
   at System.DrawingCore.FontFamily.get_GenericSansSerif()
   at System.DrawingCore.Font.CreateFont(String familyName, Single emSize, FontStyle style, GraphicsUnit unit, Byte charSet, Boolean isVertical)
   at Common.VerifyCodeHelper.CreateByteByImgVerifyCode(String verifyCode, Int32 width, Int32 height) in F:\src\WebApp\Common\VerifyCodeHelper.cs:line 206
   at WebApp.Controllers.VerifyCodeController.NumberVerifyCode() in F:\src\WebApp\Controllers\VerifyCodeController.cs:line 27
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextExceptionFilterAsync()

Centos 7

yum install libgdiplus-devel