Передаем в параметр (Bitmap, глубину цвета, серое или цветное)
| Код |
#region gdi32
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern bool DeleteObject(IntPtr hObject);
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern int InvalidateRect(IntPtr hwnd, IntPtr rect, int bErase);
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern IntPtr GetDC(IntPtr hwnd);
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern IntPtr CreateCompatibleDC(IntPtr hdc);
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern int ReleaseDC(IntPtr hwnd, IntPtr hdc);
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern int DeleteDC(IntPtr hdc);
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
public static extern int BitBlt(IntPtr hdcDst, int xDst, int yDst, int w, int h, IntPtr hdcSrc, int xSrc, int ySrc, int rop);
static int SRCCOPY = 0x00CC0020;
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
static extern IntPtr CreateDIBSection(IntPtr hdc, ref BITMAPINFO bmi, uint Usage, out IntPtr bits, IntPtr hSection, uint dwOffset);
static uint BI_RGB = 0;
static uint DIB_RGB_COLORS = 0;
[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct BITMAPINFO
{
public uint biSize;
public int biWidth, biHeight;
public short biPlanes, biBitCount;
public uint biCompression, biSizeImage;
public int biXPelsPerMeter, biYPelsPerMeter;
public uint biClrUsed, biClrImportant;
[System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst = 256)]
public uint[] cols;
}
static uint MAKERGB(int r, int g, int b)
{
return ((uint)(b & 255)) | ((uint)((r & 255) << 8)) | ((uint)((g & 255) << 16));
}
#endregion
public static Bitmap CopyToBpp(Bitmap b, int bpp, bool grayscale)
{
// (1) Convert our Bitmap into a GDI hbitmap (ie. copy unmanaged->managed)
// (2) Create a GDI monochrome hbitmap
// (3) Use GDI "BitBlt" function to copy from hbitmap into monochrome (as above)
// (4) Convert the monochrone hbitmap into a Bitmap (ie. copy unmanaged->managed)
if (bpp != 1 && bpp != 8) throw new System.ArgumentException("1 or 8", "bpp");
int w = b.Width, h = b.Height;
IntPtr hbm = b.GetHbitmap(); // this is step (1)
// Step (2): create the monochrome bitmap.
BITMAPINFO bmi = new BITMAPINFO();
bmi.biSize = 40; // the size of the BITMAPHEADERINFO struct
bmi.biWidth = w;
bmi.biHeight = h;
bmi.biPlanes = 1;
bmi.biBitCount = (short)bpp; // ie. 1bpp or 8bpp
bmi.biCompression = BI_RGB;
bmi.biSizeImage = (uint)(((w + 7) & 0xFFFFFFF8) * h / 8);
bmi.biXPelsPerMeter = 1000000; // not really important
bmi.biYPelsPerMeter = 1000000; // not really important
// Now for the colour table.
uint ncols = (uint)1 << bpp; // 2 colours for 1bpp; 256 colours for 8bpp
bmi.biClrUsed = ncols;
bmi.biClrImportant = ncols;
bmi.cols = new uint[256]; // The structure always has fixed size 256, even if we end up using fewer colours
if (bpp == 1) { bmi.cols[0] = MAKERGB(0, 0, 0); bmi.cols[1] = MAKERGB(255, 255, 255); }
else
{
if (grayscale)
{
for (int i = 0; i < ncols; i++) bmi.cols[i] = MAKERGB(i, i, i);
}
else
{
bmi.biClrUsed = 216;
bmi.biClrImportant = 216;
int[] colv = new int[6] { 0, 51, 102, 153, 204, 255 };
for (int i = 0; i < 216; i++) bmi.cols[i] = MAKERGB(colv[i / 36], colv[(i / 6) % 6], colv[i % 6]);
}
}
IntPtr bits0;
IntPtr hbm0 = CreateDIBSection(IntPtr.Zero, ref bmi, DIB_RGB_COLORS, out bits0, IntPtr.Zero, 0);
//
// Step (3): use GDI's BitBlt function to copy from original hbitmap into monocrhome bitmap
IntPtr sdc = GetDC(IntPtr.Zero);
IntPtr hdc = CreateCompatibleDC(sdc); SelectObject(hdc, hbm);
IntPtr hdc0 = CreateCompatibleDC(sdc); SelectObject(hdc0, hbm0);
BitBlt(hdc0, 0, 0, w, h, hdc, 0, 0, SRCCOPY);
// Step (4): convert this monochrome hbitmap back into a Bitmap:
System.Drawing.Bitmap b0 = System.Drawing.Bitmap.FromHbitmap(hbm0);
//
DeleteDC(hdc);
DeleteDC(hdc0);
ReleaseDC(IntPtr.Zero, sdc);
DeleteObject(hbm);
DeleteObject(hbm0);
//
return b0;
}
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