/// <summary>
/// Used to create a bitmap from provieded bytes
/// </summary>
/// <param name="rowColors">Contains bytes of bitmap</param>
/// <returns></returns>
private Bitmap CreateBM(ColorObject[][] rowColors)
{
int width = rowColors[0].Count();
int height = rowColors.Count();
//int width = rowColors.Values.Where(o => o == 0).Count();
Bitmap bitm = new Bitmap(width, height, PixelFormat.Format24bppRgb);
// new Bitmap(imgdat.GetUpperBound(1) + 1, imgdat.GetUpperBound(0) + 1, PixelFormat.Format24bppRgb);
BitmapData bitmapdat = bitm.LockBits(new Rectangle(0, 0, bitm.Width, bitm.Height), ImageLockMode.ReadWrite, bitm.PixelFormat);
int stride = bitmapdat.Stride;
byte[] bytes = new byte[stride * bitm.Height];
for (int r = 0; r < bitm.Height; r++)
{
for (int c = 0; c < bitm.Width; c++)
{
ColorObject color = rowColors[r][c];
bytes[(r * stride) + c * 3] = color.Blue;
bytes[(r * stride) + c * 3 + 1] = color.Green;
bytes[(r * stride) + c * 3 + 2] = color.Red;
}
}
System.IntPtr scan0 = bitmapdat.Scan0;
Marshal.Copy(bytes, 0, scan0, stride * bitm.Height);
bitm.UnlockBits(bitmapdat);
return(bitm);
}
/// <summary>
/// It opens the image using memory mapped view and read the needed
/// parts, then call CreateBM to create a partially bitmap
/// </summary>
/// <param name="bmpFilename">Path to the physical bitmap</param>
/// <returns></returns>
public Bitmap readPartOfImage(string bmpFilename)
{
var headers = ReadHeaders(bmpFilename);
var mmf = MemoryMappedFile.CreateFromFile(bmpFilename, FileMode.Open);
int rowSize = headers.Item2.RowSize; // number of byes in a row
// Dictionary<ColorObject, int> rowColors = new Dictionary<ColorObject, int>();
int colorSize = Marshal.SizeOf(typeof(MyColor));
int width = rowSize / colorSize;//(headers.Item1.DataOffset+ rowSize) / colorSize;
int height = 200;
ColorObject cObj;
MyColor outObj;
ColorObject[][] rowColors = new ColorObject[height][];
// Read the view image and save row by row pixel
for (int j = 0; j < height; j++)
{
rowColors[j] = new ColorObject[width];
using (var view = mmf.CreateViewAccessor(headers.Item1.DataOffset + rowSize * j, rowSize, MemoryMappedFileAccess.Read))
{
for (long i = 0; i < rowSize; i += colorSize)
{
view.Read(i, out outObj);
cObj = new ColorObject(outObj);
rowColors[j][i / colorSize] = cObj;
}
}
}
return(CreateBM(rowColors));
}