C#中使用byte[]資料，產生Bitmap

/// <summary>

/// 使用byte[]資料，產生256色灰階　BMP 位元影像

/// </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);

//將該位元影像存入記憶體中

MemoryStream curImageStream = new MemoryStream();

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

curImageStream.Flush();

//由於位元影像資料需要DWORD對齊（4byte倍數），計算需要補位的個數

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

//最終產生的位元影像資料大小

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

//資料部分相對檔案開始位移，具體可以參考位元影像檔案格式

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

//改變調色盤，因為預設的調色盤是32位彩色的，需要修改為256色的調色盤

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);

}

//最終產生的位元影像資料，以及大小，高度沒有變，寬度需要調整

byte[] destImageData = new byte[bitmapDataSize];

int destWidth = originalWidth + curPadNum;

//產生最終的位元影像資料，注意的是，位元影像資料 從左至右，從下到上，所以需要顛倒

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

{

int destRowIndex = originalHeight - originalRowIndex - 1;

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

{

//同時還要注意，新的位元影像資料的寬度已經變化destWidth，否則會產生錯位

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

}

}

//將流的Position移到資料區段　　

curImageStream.Position = dataOffset;

//將新位元影像資料寫入記憶體中

curImageStream.Write(destImageData, 0, bitmapDataSize);

curImageStream.Flush();

//將記憶體中的位元影像寫入Bitmap對象

resultBitmap = new Bitmap(curImageStream);

return resultBitmap;

}

/// <summary>

/// 從記憶體流中指定位置，讀取資料

/// </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>

/// 向記憶體流中指定位置，寫入資料

/// </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);

}