// 以下、ビットマップファイル作成まわりの関数
static WORD _DibNumColors(LPVOID pv)
{
	// With the BITMAPINFO format headers, the size of the palette is in biClrUsed, whereas in the BITMAPCORE - style headers,
	// it is dependent on the bits per pixel ( = 2 raised to the power of bits/pixel).
	LPBITMAPINFOHEADER lpbi = ((LPBITMAPINFOHEADER)pv);
	LPBITMAPCOREHEADER lpbc = ((LPBITMAPCOREHEADER)pv);
	int bits = 0;
	if (lpbi->biSize != sizeof(BITMAPCOREHEADER))
	{
		if (lpbi->biClrUsed != 0)
		{
			if (0.0 <= lpbi->biClrUsed && lpbi->biClrUsed <= 65535.0)
				return (WORD)lpbi->biClrUsed;
			else
				return(256);
		}
		bits = lpbi->biBitCount;
	}
	else
		bits = lpbc->bcBitCount;
	switch (bits)
	{
		case 1:	return 2;
		case 4:	return 16;
		case 8:	return 256;
		default: return 0;  // A 24 bitcount DIB has no color table
	}
}

static BOOL _CreateDIBPalette(BYTE* lpDibBmp, CPalette& pal)
{
	// BITMAPINFOへのポインタ取得
	LPBITMAPINFO lpbmi = NULL;
	if (!(lpbmi = (LPBITMAPINFO)lpDibBmp))
		return FALSE;

	// BITMAPCOREINFOへのポインタ取得
	LPBITMAPCOREINFO lpbmc = (LPBITMAPCOREINFO)lpDibBmp;

	// DIB 内の色数を取得
	BOOL bResult = FALSE;
	WORD wNumColors = _DibNumColors(lpbmi);
	if (wNumColors == 0)
		return bResult;

	// バージョンおよびパレットのエントリ数を設定
	LPLOGPALETTE lpPal = (LPLOGPALETTE)new char[sizeof(LOGPALETTE) + sizeof(PALETTEENTRY) * wNumColors];
	lpPal->palVersion = 0x300;
	lpPal->palNumEntries = (WORD)wNumColors;
	bool blWinStyleDIB = (*(LPDWORD)(lpDibBmp)) == sizeof(BITMAPINFOHEADER) ? true : false;
	for (int i = 0; i < (int)wNumColors; i++)
	{
		if (blWinStyleDIB)
		{
			lpPal->palPalEntry[i].peRed = lpbmi->bmiColors[i].rgbRed;
			lpPal->palPalEntry[i].peGreen = lpbmi->bmiColors[i].rgbGreen;
			lpPal->palPalEntry[i].peBlue = lpbmi->bmiColors[i].rgbBlue;
			lpPal->palPalEntry[i].peFlags = 0;
		}
		else
		{
			lpPal->palPalEntry[i].peRed = lpbmc->bmciColors[i].rgbtRed;
			lpPal->palPalEntry[i].peGreen = lpbmc->bmciColors[i].rgbtGreen;
			lpPal->palPalEntry[i].peBlue = lpbmc->bmciColors[i].rgbtBlue;
			lpPal->palPalEntry[i].peFlags = 0;
		}
	}
	// パレットを作成してハンドル取得
	bResult = pal.CreatePalette(lpPal);
	delete[] lpPal;
	return bResult;
}

static WORD _PaletteSize(LPBITMAPINFOHEADER lpbi)
{
	WORD NumColors;
	NumColors = _DibNumColors(lpbi);
	if (lpbi->biSize == sizeof(BITMAPCOREHEADER))
		return NumColors * sizeof(RGBTRIPLE);
	else
		return NumColors * sizeof(RGBQUAD);
}

static void _SaveImageFile(HBITMAP hBmp, LPCTSTR filename)
{
	// BITMAP情報を取得する
	BITMAP bmp = { 0 };
	GetObject(hBmp, sizeof(bmp), &bmp);
	HDC hdc = GetDC(0);
	HDC hdc_mem = CreateCompatibleDC(hdc);
	ReleaseDC(0, hdc);
	HBITMAP hBmpOld = (HBITMAP)SelectObject(hdc_mem, hBmp);

	// ファイルサイズ計算
	LONG imageSize = bmp.bmWidthBytes * bmp.bmHeight + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
	LONG bpp;  // 画素数
	switch (bmp.bmBitsPixel)
	{
		case 2:  bpp = 2;  break;
		case 4:  bpp = 16;  break;
		case 8:  bpp = 256;  break;
		default:  bpp = 0;
	}
	imageSize += (sizeof(RGBQUAD) * bpp);

	// BITMAPFILEHEADERヘッダー出力
	BITMAPFILEHEADER fh;
	ZeroMemory(&fh, sizeof(fh));
	memcpy(&fh.bfType, "BM", 2);
	fh.bfSize = imageSize;
	fh.bfReserved1 = 0;
	fh.bfReserved2 = 0;
	fh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * bpp;

	// BITMAPINFOHEADERヘッダー出力
	BITMAPINFO* pbi = new BITMAPINFO[sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * bpp];
	ZeroMemory(pbi, sizeof(BITMAPINFOHEADER));
	pbi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	pbi->bmiHeader.biWidth = bmp.bmWidth;
	pbi->bmiHeader.biHeight = bmp.bmHeight;
	pbi->bmiHeader.biPlanes = 1;
	pbi->bmiHeader.biBitCount = bmp.bmBitsPixel;
	pbi->bmiHeader.biCompression = BI_RGB;
	if (bpp != 0)
		GetDIBColorTable(hdc_mem, 0, bpp, pbi->bmiColors);

	// 画像データを得る
	LPBYTE bits = new BYTE[bmp.bmWidthBytes * bmp.bmHeight];
	GetDIBits(hdc_mem, hBmp, 0, bmp.bmHeight, bits, pbi, DIB_RGB_COLORS);

	// ファイルに書き込む
	HANDLE hFile = CreateFile(filename, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
	DWORD writeSize;  // 書き込んだサイズ
	WriteFile(hFile, &fh, sizeof(fh), &writeSize, NULL);
	WriteFile(hFile, pbi, sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * bpp, &writeSize, NULL);
	WriteFile(hFile, bits, bmp.bmWidthBytes * bmp.bmHeight, &writeSize, NULL);
	CloseHandle(hFile);

	// 開放
	delete[] pbi;
	delete[] bits;
	SelectObject(hdc_mem, hBmpOld);
	DeleteDC(hdc_mem);
}

static bool _WriteBitmap(CDC* pDC, BYTE* lpDibBmp, LPCTSTR pFile)
{
	LPBITMAPINFOHEADER lpbi = NULL;
	if (!(lpbi = (LPBITMAPINFOHEADER)lpDibBmp))
		return false;

	// パレットがある場合は、パレットを選択する
	CPalette pal;
	CPalette* pOldPal = NULL;
	if (_CreateDIBPalette(lpDibBmp, pal))
	{
		pOldPal = pDC->SelectPalette(&pal, FALSE);
		pDC->RealizePalette();
	}

	// DDB ビットマップのクリエイト
	HBITMAP hbm = CreateDIBitmap(pDC->m_hDC, (LPBITMAPINFOHEADER)lpbi, (LONG)CBM_INIT, (LPBYTE)lpbi + lpbi->biSize + _PaletteSize(lpbi),
		(LPBITMAPINFO)lpbi, DIB_RGB_COLORS);

	// パレットを元に戻す
	if (pOldPal)
		pDC->SelectPalette(pOldPal, FALSE);

	_SaveImageFile(hbm, pFile);
	::DeleteObject(hbm);

	return true;
}