[英]Get raw data back from instance of Image
我從資源獲取Image(實際上是Bitmap類的實例),並且(將它寫入rtf流) - 我需要它的原始數據。
此外,Image.Save方法不能使用,因為它似乎關閉流保存到,我需要附加到RTF文件。 我不想創建新流,將圖像保存到它,然后由於性能問題將其復制到RTF流。
創建一個過濾器流,該過濾器流將傳遞給您要附加到的流,但在它自身關閉時不會關閉該流:
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);
}
}
然后你就不再有關閉流的問題,因為它沒關系。
處理尋找新位置的位是因為某些圖像格式是以非順序方式寫入的。 如果底層流不支持它,它將無法工作,但無論如何這將無法工作。
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