Trouble saving JPGs using Intel Library

[MacLeod72]

Hello All-

I am trying to save an image of the screen as a JPEG. Through testing I know that my code will grab a device-dependent bitmap of the screen and convert it into a device-independent bitmap. However, when I attempt to save the DIB as a JPG using the Intel JPEG library, I get a scrambled image saved and the ijlWrite() command returns -1, which is documented as "Exception Encountered". From what I understand, the code should be generating an upside-down full size image of the desktop. I would be grateful for any help.

Thanks!

--Rob


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	HWND hDesktop;
	HDC hDesktopDC, hCompatDC;
	HBITMAP hBmpScreen, hBmpA;
	LPBITMAPINFO lpbmiDIBInfo = (LPBITMAPINFO)(new char[sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD)]);
	int iScreenWidth, iScreenHeight;
	LPVOID lpvDIBBytes;
	JPEG_CORE_PROPERTIES *pjcpJPEG;


	iScreenWidth = GetSystemMetrics(SM_CXSCREEN);
	iScreenHeight = GetSystemMetrics(SM_CYSCREEN);
	hDesktop = ::GetDesktopWindow();
	hDesktopDC = ::GetDC(hDesktop);
	hCompatDC = CreateCompatibleDC(hDesktopDC);
	hBmpScreen = CreateCompatibleBitmap(hDesktopDC, iScreenWidth, iScreenHeight);
	hBmpA = (HBITMAP) SelectObject(hCompatDC, hBmpScreen);
	BitBlt(hCompatDC, 0, 0, iScreenWidth, iScreenHeight, hDesktopDC, 0,0,SRCCOPY);
	::ReleaseDC(hDesktop, hDesktopDC);

	memset(lpbmiDIBInfo, 0, sizeof(*lpbmiDIBInfo));
	pjcpJPEG = new JPEG_CORE_PROPERTIES;
	memset(pjcpJPEG, 0, sizeof(JPEG_CORE_PROPERTIES));
	lpbmiDIBInfo->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

// Deselect Bitmap for DIb conversion
	SelectObject(hCompatDC, hBmpA);

// Retrieve Header Info
	GetDIBits(hCompatDC, hBmpScreen, 0, iScreenHeight, NULL, lpbmiDIBInfo, DIB_RGB_COLORS);
	lpvDIBBytes = new BYTE[lpbmiDIBInfo->bmiHeader.biSizeImage];

// Create DIB in (void *)
	GetDIBits(hCompatDC, hBmpScreen, 0, iScreenHeight, lpvDIBBytes, lpbmiDIBInfo, DIB_RGB_COLORS);

// Clear Bitmap
	DeleteDC(hCompatDC);
	DeleteObject(hBmpScreen);

// Save JPG from DIB
	ijlInit(pjcpJPEG);

	pjcpJPEG->DIBWidth = lpbmiDIBInfo->bmiHeader.biWidth;
	pjcpJPEG->DIBHeight = lpbmiDIBInfo->bmiHeader.biHeight;
	pjcpJPEG->DIBChannels = 3;
	pjcpJPEG->DIBSubsampling = IJL_NONE;
	pjcpJPEG->DIBColor = IJL_BGR;
	pjcpJPEG->DIBBytes = (unsigned char *) lpvDIBBytes;
	pjcpJPEG->DIBPadBytes = IJL_DIB_PAD_BYTES(pjcpJPEG->DIBWidth,pjcpJPEG->DIBChannels);

	pjcpJPEG->JPGWidth = lpbmiDIBInfo->bmiHeader.biWidth;
	pjcpJPEG->JPGHeight = lpbmiDIBInfo->bmiHeader.biHeight;
	pjcpJPEG->JPGChannels = 3;
	pjcpJPEG->JPGSubsampling = IJL_411;
	pjcpJPEG->JPGColor = IJL_YCBCR;
	pjcpJPEG->JPGFile = "c:\\test.jpg";
	pjcpJPEG->jquality = 100;

	ijlWrite(pjcpJPEG, IJL_JFILE_WRITEWHOLEIMAGE);

	ijlFree(pjcpJPEG);

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[tchouch]

Test this code with 256 display colors - many converters do not work with more colors, and Your Functions use display settings.

 

[MacLeod72]

Thanks for the idea! However, the image still doesn't come out.

--Rob