devxlogo

ImageFormatUtils class – Find the ImageFormat for a filename or MIME type

ImageFormatUtils class – Find the ImageFormat for a filename or MIME type

'/// '/// Provides static (Shared) methods to find the'/// ImageFormat for a filename or MIME type.'/// Public NotInheritable Class ImageFormatUtils    Private Shared codecs() As ImageCodecInfo    Private Shared formats As Hashtable        Shared Sub New()        '// Get a combined list of all codecs        Dim encoders() As ImageCodecInfo = ImageCodecInfo.GetImageEncoders()        If encoders Is Nothing Then ReDim encoders(0)        Dim decoders() As ImageCodecInfo = ImageCodecInfo.GetImageDecoders()        If decoders Is Nothing Then ReDim decoders(0)                Dim codec As ImageCodecInfo        Dim htCodecs As new Hashtable(encoders.Length + decoders.Length)        Dim i As Integer                For i = 0 To encoders.Length - 1            codec = encoders(i)            htCodecs.Add(codec.Clsid, codec)        Next        For i = 0 To decoders.Length - 1            codec = decoders(i)            If Not htCodecs.ContainsKey(codec.Clsid) Then                htCodecs.Add(codec.Clsid, codec)            End If        Next                ReDim codecs(htCodecs.Count - 1)        htCodecs.Values.CopyTo(codecs, 0)                '// Enumerate the pre-defined formats        Try            Dim tImageFormat As Type = GetType(ImageFormat)            Dim props() As PropertyInfo = tImageFormat.GetProperties _                (BindingFlags.Public Or BindingFlags.Static)            Dim prop As PropertyInfo            Dim format As ImageFormat                        formats = new Hashtable(props.Length)            For i = 0 To props.Length - 1                prop = props(i)                If prop.PropertyType Is tImageFormat Then                    format = DirectCast(prop.GetValue(Nothing, Nothing), _                        ImageFormat)                    formats.Add(format.Guid, format)                End If            Next        Catch        End Try    End Sub        '///     '/// Returns the ImageFormat instance for the    '/// specified format ID. Uses reflection to    '/// test the static instances of the class    '/// for the correct ID, before using the    '/// constructor.    '///     '///     '/// The Guid which contains the format ID.    '///     '///     '/// The corresponding ImageFormat object.    '///     Public Shared Function FromID(ByVal formatID As Guid) As ImageFormat        If formats Is Nothing OrElse Not formats.ContainsKey(formatID) Then            Return New ImageFormat(formatID)        Else            Return DirectCast(formats(formatID), ImageFormat)        End If    End Function        '///     '/// Returns the ImageCodecInfo which corresponds    '/// to the specified MIME type.    '///     '///     '/// The MIME type, e.g. "image/jpeg"    '///     '///     '/// The ImageCodecInfo for the MIME type.    '///     Public Shared Function CodecFromMime(ByVal mimeType As String) As _        ImageCodecInfo        If mimeType Is Nothing OrElse 0 = mimeType.Length Then            Throw New ArgumentNullException("mimeType")        End If                Dim i As Integer        For i = 0 To codecs.Length - 1            If 0 = String.Compare(codecs(i).MimeType, mimeType, true) Then                Return codecs(i)            End If        Next                Return Nothing    End Function        '///     '/// Returns the ImageFormat which corresponds    '/// to the specified MIME type.    '///     '///     '/// The MIME type, e.g. "image/jpeg"    '///     '///     '/// The ImageFormat for the MIME type.    '///     Public Shared Function FromMime(ByVal mimeType As String) As ImageFormat        If mimeType Is Nothing OrElse 0 = mimeType.Length Then            Throw New ArgumentNullException("mimeType")        End If                Dim info As ImageCodecInfo = CodecFromMime(mimeType)        If info Is Nothing Then            Return Nothing        Else            Return FromID(info.FormatID)        End If    End Function        '///     '/// Returns an ImageCodecInfo which corresponds    '/// to the extension of the supplied filename.    '///     '///     '/// The filename or extension of the image.    '///     '///     '/// The ImageCodecInfo for the filename.    '///     Public Shared Function CodecFromExtension(ByVal filename As String) As _        ImageCodecInfo        If filename Is Nothing OrElse 0 = filename.Length Then            Throw New ArgumentNullException("filename")        End If                Dim index As Integer = filename.LastIndexOf("."c)        If -1 = index Then Return Nothing                Dim ext As String = "*." & filename.Substring(index + 1)        Dim i As Integer        For i = 0 To codecs.Length - 1            Dim extensions() As String = codecs(i).FilenameExtension.Split(";"c)            Dim j As Integer            For j = 0 To extensions.Length - 1                If 0 = String.Compare(extensions(j), ext, true) Then                    Return codecs(i)                End If            Next        Next                Return Nothing    End Function        '///     '/// Returns an ImageFormat which corresponds    '/// to the extension of the supplied filename.    '///     '///     '/// The filename or extension of the image.    '///     '///     '/// The ImageFormat for the filename.    '///     Public Shared Function FromExtension(ByVal filename As String) As _        ImageFormat        If filename Is Nothing OrElse 0 = filename.Length Then            Throw New ArgumentNullException("filename")        End If                Dim info As ImageCodecInfo = CodecFromExtension(filename)        If info Is Nothing Then            Return Nothing        Else            Return FromID(info.FormatID)        End If    End Function        '///     '/// No need to create an instance of this class.    '///     Private Sub New()    End SubEnd Class' *******************' * SAMPLE USAGE' *******************Option ExplicitOption StrictImports SystemImports System.CollectionsImports System.ReflectionImports System.Drawing.ImagingClass App    Shared Sub Main()        Try            Dim file As String            Dim index As Integer            Dim codec As ImageCodecInfo                        do                Console.Write("Enter a file name or MIME type: ")                file = Console.ReadLine()                                If Not (file Is Nothing) AndAlso 0 < file.Length Then                    index = file.IndexOf("/"c)                    If -1 = index Then                        codec = ImageFormatUtils.CodecFromExtension(file)                    Else                        codec = ImageFormatUtils.CodecFromMime(file)                    End If                                        If codec Is Nothing Then                        Console.WriteLine("Unknown format.")                    Else                        WriteCodec(codec)                    End If                                        Console.WriteLine()                End If            Loop While Not(file Is Nothing) AndAlso 0 < file.Length                    Catch ex As Exception            Console.WriteLine(ex)        End Try    End Sub        Shared Sub WriteCodec(ByVal codec As ImageCodecInfo)        If codec Is Nothing Then Throw New ArgumentNullException("codec")                Console.WriteLine("Format: {0}", ImageFormatUtils.FromID(codec.FormatID) _            )        Console.WriteLine("Name: {0}", codec.CodecName)        Console.WriteLine("DLL: {0}", codec.DllName)        Console.WriteLine("Version: {0}", codec.Version)        Console.WriteLine("Extension: {0}", codec.FilenameExtension)        Console.WriteLine("MIME: {0}", codec.MimeType)    End SubEnd Class

See also  How HealthStream Learning Center Supports Healthcare Education and Compliance
devxblackblue

About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

About Our Journalist