CreateDIBSection and Access violation

[Ralf Schneider]

Hello,

I hope, some of the experts can help me.
I want to draw to a DIB created with CreateDIBSection, but I get an access violation.

	BITMAPINFO bmi;
	memset(&bmi,0,sizeof(BITMAPINFO));
	tBYTE*            lpBits;
	bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
     glTexSize=4096;
	bmi.bmiHeader.biWidth = glTexSize;
	bmi.bmiHeader.biHeight = glTexSize;
	bmi.bmiHeader.biPlanes = 1;                     /* must be 1 */
	bmi.bmiHeader.biBitCount = 24;
	bmi.bmiHeader.biCompression = BI_RGB;

	// Create DIB for rendering context
	tHANDLE dib =CreateDIBSection(dcMem.m_hDC,&bmi,DIB_RGB_COLORS,(void**)&lpBits, NULL, 0);
	tHANDLE old=::SelectObject(dcMem.m_hDC,dib);

     // Draw to dcMem with GDI
        .......

Draw to dcMem leads to an access violation.
What is wrong?
Do I need to allocate memory?

thx.

[MrViggy]

What is 'dcMem'? How is it being created?

Viggy

[Ralf Schneider]

What is 'dcMem'? How is it being created?

Viggy

CDC dcMem;
dcMem.CreateCompatibleDC(NULL);

[MikeAThon]

	// ... snip ...
	tBYTE*            lpBits;

	// ... snip ...
	tHANDLE dib =CreateDIBSection(dcMem.m_hDC,&bmi,DIB_RGB_COLORS,(void**)&lpBits, NULL, 0);

What's a "tBYTE"? The fact that you had to forcefully cast it, in order to get the CreateDIBSection call to compile, should have been a hint that you are using the wrong type.

Try this:

	// ... snip ...
	void*            lpBits;

	// ... snip ...
	tHANDLE dib =CreateDIBSection(dcMem.m_hDC,&bmi,DIB_RGB_COLORS, /* no cast needed (void**) */ &lpBits, NULL, 0);