Question

我从资源获取Image（实际上是Bitmap类的实例），并且（将其写入rtf流） - 我需要它的原始数据。

另外，Image.Save方法不能使用，因为它似乎关闭了它保存到的流，我需要附加到RTF文件。我不想创建新的流，将图像保存到它，然后由于性能问题将其复制到RTF流。

Answer 1

创建一个过滤器流，该过滤器流将传递给您要附加到的流，但在它自身关闭时不会关闭该流：

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);
    }
}

然后你就不再有关闭流的问题，因为它没关系。

处理寻找新位置的位是因为某些图像格式是以非顺序方式写入的。如果底层流不支持它，它将无法工作，但那无论如何都无法工作。

从Image实例中获取原始数据

1 个答案: