Get raw data from an Image instance

Question

I get Image (actually an instance of the Bitmap class) from resources and (to write it to the rtf stream) - I need its raw data.

In addition, the Image.Save method cannot be used because it closes the stream that it saves, and I need to add the RTF file. I do not want to create a new stream, save the image to it, and then copy it to the RTF stream due to performance problems.

Answer 1

Create a filter stream, which will be passed to the stream to which you want to add, but does not close this stream when it is closed:

public class AppendingStream : Stream { private readonly long _startPos; private readonly Stream _sink; public AppendingStream(Stream sink) { if(sink == null) throw new ArgumentNullException(); if(!sink.CanWrite) throw new ArgumentException(); _sink = sink; try { _startPos = sink.Position; } catch(NotSupportedException) { _startPos = -1; } } public override bool CanRead { get { return false; } } public override bool CanSeek { get { return _sink.CanSeek && _startPos != -1; } } public override bool CanTimeout { get { return _sink.CanTimeout; } } public override bool CanWrite { get { return true; } } public override long Length { get { if(_startPos == -1) throw new NotSupportedException(); return _sink.Length - _startPos; } } public override long Position { get { return _sink.Position - _startPos; } set { _sink.Position = value + _startPos; } } public override void Flush() { _sink.Flush(); } public override int Read(byte[] buffer, int offset, int count) { throw new NotSupportedException(); } public override int ReadByte() { throw new NotSupportedException(); } public override long Seek(long offset, SeekOrigin origin) { if(origin == SeekOrigin.Begin) return _sink.Seek(offset + _startPos, SeekOrigin.Begin) - _startPos; else return _sink.Seek(offset, origin); } public override void SetLength(long value) { if(_startPos == -1) throw new NotSupportedException(); _sink.SetLength(value + _startPos); } public override void Write(byte[] buffer, int offset, int count) { _sink.Write(buffer, offset, count); } public override void WriteByte(byte value) { _sink.WriteByte(value); } } 

Then you no longer have a problem closing the stream, as that doesn't matter.

Bits for finding new positions is that some image formats are not recorded sequentially. It will not work if the underlying thread does not support it, but then it will not work.