why CreateDIBSection() fails with certian BITMAPINFO? - c++

Question

I am trying to use CreateDIBSection.
Problem:
In Windows XP, I tried to call CreateDIBSection, it returns NULL and GetLastError = 0
When I try to change the screen resolution, for example to 2048 x 1536, it returns correct value.
I have tested this function has some relationship with nMemSize (not necessarily small number).
Question:
Is there any guarantee way to ensure CreateDIBSection returns correct value?
nScreenWidth = 1024;
nScreenHeight= 768;
= nScreenWidth*nScreenHeight*3*7
HDC hdc = ::GetDC(hWnd);
m_hBmpMapFile = ::CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, nMemSize, NULL);
BITMAPINFO bmpInfo = {0};
bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmpInfo.bmiHeader.biWidth = nScreenWidth;
bmpInfo.bmiHeader.biHeight = nScreenHeight;
bmpInfo.bmiHeader.biPlanes = 1;
bmpInfo.bmiHeader.biBitCount = 24;
bmpInfo.bmiHeader.biCompression = 0;
bmpInfo.bmiHeader.biSizeImage = nMemSize;
bmpInfo.bmiHeader.biXPelsPerMeter = 0;
bmpInfo.bmiHeader.biYPelsPerMeter = 0;
bmpInfo.bmiHeader.biClrUsed = 0;
bmpInfo.bmiHeader.biClrImportant = 0;
bmpInfo.bmiColors[0].rgbBlue = 204;
bmpInfo.bmiColors[0].rgbGreen = 204;
bmpInfo.bmiColors[0].rgbRed = 204;
bmpInfo.bmiColors[0].rgbReserved = 0;
PVOID pvBits;
m_hBmpAllWstDskWallpaper = ::CreateDIBSection(hdc, &bmpInfo, DIB_RGB_COLORS, &pvBits, m_hBmpMapFile, 0);

Answer 1

I suspect the problem might be contained in the section of code that you did not include (in the elipses ...). So I recommend:
Check your Device Context is valid
ZeroMemory
Add the structure size
And bitmap dimensions
Move the GetLastError calls to ensure that the Device Context is valid (perhaps an earlier API call fails)
The code below seems to work after I added the recommendations above, I hope it helps:
HDC hdc = ::GetDC(hWnd);
int nScreenWidth = 1024;
int nScreenHeight= 768;
int nMemSize = nScreenWidth*nScreenHeight*3*7;
HANDLE m_hBmpMapFile = ::CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, nMemSize, NULL);
BITMAPINFO bmpInfo;
//clear the memory
ZeroMemory(&bmpInfo.bmiHeader, sizeof(BITMAPINFOHEADER));
//struct size
bmpInfo.bmiHeader.biSize = sizeof (BITMAPINFOHEADER);
//dimensions
bmpInfo.bmiHeader.biWidth = nScreenWidth;
bmpInfo.bmiHeader.biHeight = nScreenHeight;
bmpInfo.bmiHeader.biPlanes = 1;
bmpInfo.bmiHeader.biBitCount = 32;
bmpInfo.bmiHeader.biSizeImage=nMemSize;
void *pvBits = NULL;
HANDLE m_hBmpAllWstDskWallpaper = ::CreateDIBSection(hdc, &bmpInfo, DIB_RGB_COLORS, &pvBits, m_hBmpMapFile, 0);
int nError = ::GetLastError();