從圖像實例獲取原始數據

Question

我從資源獲取圖像（實際上是位圖類的實例），並且（將其寫入rtf流） - 我需要原始數據。

此外，Image.Save方法不能使用，因爲它似乎關閉流保存到，我需要追加到RTF文件。我不想創建新的流，將圖像保存到它，然後將其複製到RTF流，因爲性能問題。

Answer 1

創建通過您要附加到流通過一個過濾器流，但不會關閉該流時，它本身是封閉的：

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); 
    } 
} 

那麼你已經不再有問題該流被關閉，因爲它並不重要。

處理尋找新位置的位是因爲某些圖像格式是以非順序方式寫入的。如果底層的流不支持它，它將不起作用，但是那樣不會起作用。