XmlReader.ReadElementContentAsBinHex(Byte[], Int32, Int32) Method

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlReader.cs

Reads the element and decodes the BinHex content.

public:
 virtual int ReadElementContentAsBinHex(cli::array <System::Byte> ^ buffer, int index, int count);

public virtual int ReadElementContentAsBinHex (byte[] buffer, int index, int count);

abstract member ReadElementContentAsBinHex : byte[] * int * int -> int
override this.ReadElementContentAsBinHex : byte[] * int * int -> int

Public Overridable Function ReadElementContentAsBinHex (buffer As Byte(), index As Integer, count As Integer) As Integer

Parameters

buffer

Byte[]

The buffer into which to copy the resulting text. This value cannot be null.

index

Int32

The offset into the buffer where to start copying the result.

count

Int32

The maximum number of bytes to copy into the buffer. The actual number of bytes copied is returned from this method.

Returns

Int32

The number of bytes written to the buffer.

Exceptions

ArgumentNullException

The buffer value is null.

InvalidOperationException

The current node is not an element node.

-or-

An XmlReader method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message "An asynchronous operation is already in progress."

ArgumentOutOfRangeException

The index into the buffer or index + count is larger than the allocated buffer size.

NotSupportedException

The XmlReader implementation does not support this method.

XmlException

The element contains mixed-content.

FormatException

The content cannot be converted to the requested type.

Examples

The following example reads an inline BinHex encoded image. The BinHex data is embedded within the <image> element. A BinaryWriter is used to create a new binary data file.

public static void BinHexDecodeImageFile() {

  byte[] buffer = new byte[1000];
  int readBytes = 0;

  using (XmlReader reader = XmlReader.Create("output.xml")) {
                    
        FileStream outputFile = new FileStream(@"C:\artFiles\data\newImage.jpg", FileMode.OpenOrCreate,
                                                                      FileAccess.Write, FileShare.Write);
        // Read to the image element.
        reader.ReadToFollowing("image");
        // Read the BinHex data.
        Console.WriteLine("\r\nReading BinHex...");
        BinaryWriter bw = new BinaryWriter(outputFile);
        while ((readBytes = reader.ReadElementContentAsBinHex(buffer, 0, 50))>0) {
            bw.Write(buffer, 0, readBytes);
        }
        outputFile.Close();
  }
}

Public Shared Sub BinHexDecodeImageFile() 
    
    Dim buffer(999) As Byte
    Dim readBytes As Integer = 0
    
    Using reader As XmlReader = XmlReader.Create("output.xml")
            
            Dim outputFile As New FileStream("C:\artFiles\data\newImage.jpg", FileMode.OpenOrCreate, FileAccess.Write, FileShare.Write)
            ' Read to the image element.
            reader.ReadToFollowing("image")
            ' Read the BinHex data.
            Console.WriteLine(vbCr + vbLf + "Reading BinHex...")
            Dim bw As New BinaryWriter(outputFile)
            readBytes = reader.ReadElementContentAsBinHex(buffer, 0, 50)
            While (readBytes > 0)
                bw.Write(buffer, 0, readBytes)
                readBytes = reader.ReadElementContentAsBinHex(buffer, 0, 50)
            End While
            outputFile.Close()
        
    End Using

End Sub

Remarks

This method reads the element content, decodes it using BinHex encoding, and returns the decoded binary bytes (for example, an inline BinHex-encoded GIF image) into the buffer.

This method can only read simple-content elements. The element can contain text, white space, significant white space, CDATA sections, comments and processing instructions. It can also contain entity references, which are automatically expanded. The element cannot have child elements.

This method is very similar to the ReadContentAsBinHex method except that it can only be called on element node types.

If the count value is higher than the number of bytes in the document, or if it is equal to the number of bytes in the document, the XmlReader reads all the remaining bytes in the document and returns the number of bytes read. The next XmlReader method call returns a zero and moves the reader to the node following the EndElement.

If you call Read before all of the element content is consumed, the reader may behave as if the first content was consumed and then the Read method was called. This means that the reader will read all the text until the end element is encountered. It will then read the end tag node, read the next node, and then position itself on the next subsequent node.

For the asynchronous version of this method, see ReadElementContentAsBinHexAsync.

See also

• ReadContentAsBinHex(Byte[], Int32, Int32)