C++ Save Bitmap file - c++

Question

I'm working on an application that captures the user's screen and saved in bitmap.
I'm having problems when creating the file
HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
I am getting the following error in filename:
argument of type "LPCSTR" is incompatible with parameter of type "LPCWSTR"
below is the code:
#include <olectl.h>
bool saveBitmap(LPCSTR filename, HBITMAP bmp, HPALETTE pal)
{
bool result = false;
PICTDESC pd;
pd.cbSizeofstruct = sizeof(PICTDESC);
pd.picType = PICTYPE_BITMAP;
pd.bmp.hbitmap = bmp;
pd.bmp.hpal = pal;
LPPICTURE picture;
HRESULT res = OleCreatePictureIndirect(&pd, IID_IPicture, false,
reinterpret_cast<void**>(&picture));
if (!SUCCEEDED(res))
return false;
LPSTREAM stream;
res = CreateStreamOnHGlobal(0, true, &stream);
if (!SUCCEEDED(res))
{
picture->Release();
return false;
}
LONG bytes_streamed;
res = picture->SaveAsFile(stream, true, &bytes_streamed);
HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
if (!SUCCEEDED(res) || !file)
{
stream->Release();
picture->Release();
return false;
}
HGLOBAL mem = 0;
GetHGlobalFromStream(stream, &mem);
LPVOID data = GlobalLock(mem);
DWORD bytes_written;
result = !!WriteFile(file, data, bytes_streamed, &bytes_written, 0);
result &= (bytes_written == static_cast<DWORD>(bytes_streamed));
GlobalUnlock(mem);
CloseHandle(file);
stream->Release();
picture->Release();
return result;
}
void CaptureScreen()
{
int nScreenWidth = GetSystemMetrics(SM_CXSCREEN);
int nScreenHeight = GetSystemMetrics(SM_CYSCREEN);
HWND hDesktopWnd = GetDesktopWindow();
HDC hDesktopDC = GetDC(hDesktopWnd);
HDC hCaptureDC = CreateCompatibleDC(hDesktopDC);
HBITMAP hCaptureBitmap = CreateCompatibleBitmap(hDesktopDC,
nScreenWidth, nScreenHeight);
SelectObject(hCaptureDC, hCaptureBitmap);
BitBlt(hCaptureDC, 0, 0, nScreenWidth, nScreenHeight,
hDesktopDC, 0, 0, SRCCOPY | CAPTUREBLT);
LPCSTR fname = "c:\\Users\\hom3r\\Downloads\\image.bmp";
HPALETTE hpal = NULL;
saveBitmap(fname, hCaptureBitmap, hpal);
ReleaseDC(hDesktopWnd, hDesktopDC);
DeleteDC(hCaptureDC);
DeleteObject(hCaptureBitmap);
}

Answer 1

You have UNICODE defined in your project, meaning that you are using the wide-character version of the Windows API. LPC[W]STR is Long Pointer to C [Wide] String.
You can either remove the UNICODE define to use the 8-bit ASCII interface, or better, use wide characters throughout your application.

Answer 2

You have to convert file_name from LPCSTR to LPCWSTR using ATL (Active Template Library).
Hence, replace
HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
with
HANDLE file = CreateFile(A2W(filename), GENERIC_WRITE, FILE_SHARE_READ, 0,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
A2W (ANSI to wide) is defined in <atlbase.h>.

Answer 3

Try to use TCHAR or wchar_t type. See similar questions at StackOverflow and MSDN.net