开发学院软件开发C语言 C#中使用byte[]数据,生成Bitmap 阅读

C#中使用byte[]数据,生成Bitmap

 2009-04-21 08:25:55 来源:WEB开发网   
核心提示:/// <summary>/// 使用byte[]数据,生成256色灰度BMP 位图/// </summary>/// <param name="originalImageData"></param>/// <param name="o

  /// <summary>

  /// 使用byte[]数据,生成256色灰度 BMP 位图

  /// </summary>

  /// <param name="originalImageData"></param>

  /// <param name="originalWidth"></param>

  /// <param name="originalHeight"></param>

  /// <returns></returns>

   public static Bitmap CreateBitmap(byte[] originalImageData, int originalWidth, int originalHeight)

  {

  //指定8位格式,即256色

   Bitmap resultBitmap = new Bitmap(originalWidth, originalHeight, System.Drawing.Imaging.PixelFormat.Format8bppIndexed);

  //将该位图存入内存中

   MemoryStream curImageStream = new MemoryStream();

  resultBitmap.Save(curImageStream, System.Drawing.Imaging.ImageFormat.Bmp);

  curImageStream.Flush();

  //由于位图数据需要DWORD对齐(4byte倍数),计算需要补位的个数

   int curPadNum = ((originalWidth * 8 + 31) / 32 * 4) - originalWidth;

  //最终生成的位图数据大小

   int bitmapDataSize = ((originalWidth * 8 + 31) / 32 * 4) * originalHeight;

  //数据部分相对文件开始偏移,具体可以参考位图文件格式

   int dataOffset = ReadData(curImageStream, 10, 4);

  //改变调色板,因为默认的调色板是32位彩色的,需要修改为256色的调色板

   int paletteStart = 54;

  int paletteEnd = dataOffset;

  int color = 0;

  for (int i = paletteStart; i < paletteEnd; i += 4)

  {

  byte[] tempColor = new byte[4];

  tempColor[0] = (byte)color;

  tempColor[1] = (byte)color;

  tempColor[2] = (byte)color;

  tempColor[3] = (byte)0;

  color++;

  curImageStream.Position = i;

  curImageStream.Write(tempColor, 0, 4);

  }

  //最终生成的位图数据,以及大小,高度没有变,宽度需要调整

   byte[] destImageData = new byte[bitmapDataSize];

  int destWidth = originalWidth + curPadNum;

  //生成最终的位图数据,注意的是,位图数据 从左到右,从下到上,所以需要颠倒

   for (int originalRowIndex = originalHeight - 1; originalRowIndex >= 0; originalRowIndex--)

  {

  int destRowIndex = originalHeight - originalRowIndex - 1;

  for (int dataIndex = 0; dataIndex < originalWidth; dataIndex++)

  {

  //同时还要注意,新的位图数据的宽度已经变化destWidth,否则会产生错位

   destImageData[destRowIndex * destWidth + dataIndex] = originalImageData[originalRowIndex * originalWidth + dataIndex];

  }

  }

  //将流的Position移到数据段  

   curImageStream.Position = dataOffset;

  //将新位图数据写入内存中

   curImageStream.Write(destImageData, 0, bitmapDataSize);

  curImageStream.Flush();

  //将内存中的位图写入Bitmap对象

   resultBitmap = new Bitmap(curImageStream);

  return resultBitmap;

  }

  /// <summary>

  /// 从内存流中指定位置,读取数据

  /// </summary>

  /// <param name="curStream"></param>

  /// <param name="startPosition"></param>

  /// <param name="length"></param>

  /// <returns></returns>

   public static int ReadData(MemoryStream curStream, int startPosition, int length)

  {

  int result = -1;

  byte[] tempData = new byte[length];

  curStream.Position = startPosition;

  curStream.Read(tempData, 0, length);

  result = BitConverter.ToInt32(tempData, 0);

  return result;

  }

  /// <summary>

  /// 向内存流中指定位置,写入数据

  /// </summary>

  /// <param name="curStream"></param>

  /// <param name="startPosition"></param>

  /// <param name="length"></param>

  /// <param name="value"></param>

   public static void WriteData(MemoryStream curStream, int startPosition, int length, int value)

  {

  curStream.Position = startPosition;

  curStream.Write(BitConverter.GetBytes(value), 0, length);

  }

Tags:使用 byte 数据

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