why CreateDIBSection() fails with certian BITMAPINFO?
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*开发者_如何学C7
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);
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();
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