C ++保存位圖文件

Question

我正在開發一個捕獲用戶屏幕並保存在位圖中的應用程序。 創建文件時遇到問題

HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
    CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);

我在文件名中遇到以下錯誤： 類型為“ LPCSTR”的參數與類型為“ LPCWSTR”的參數不兼容

下面是代碼：

    #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

您在項目中定義了UNICODE，這意味着您正在使用Windows API的寬字符版本。 LPC [W] STR是C [Wide]字符串的長指針。

您可以刪除UNICODE定義以使用8位ASCII接口，或者更好地，在整個應用程序中使用寬字符。

Answer 2

您必須使用ATL（活動模板庫）將file_name從LPCSTR轉換為LPCWSTR 。

因此，更換

HANDLE file = CreateFile(filename, GENERIC_WRITE, FILE_SHARE_READ, 0,
        CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);

同

HANDLE file = CreateFile(A2W(filename), GENERIC_WRITE, FILE_SHARE_READ, 0,
        CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);

A2W （ANSI到寬）在<atlbase.h>定義。

Answer 3

嘗試使用TCHAR或wchar_t類型。 在StackOverflow和MSDN.net上看到類似的問題