Clipboard GetClipboard GlobalLock fail.

Question

The issue is that pGlobal returns nullptr and GetlastError is 6.

if (::OpenClipboard(hWndNewOnwer))
{
HANDLE hGlobal = ::GetClipboardData(CF_UNICODETEXT);

if (hGlobal)
{
BYTE* pGlobal = (BYTE*)GlobalLock(hGlobal);
if (pGlobal != nullptr)
{
Get Clipboard Text Memory....
}
}
}

The issue is that pGlobal returns nullptr and GetlastError is 6 (The handle is invalid.)

In general, it works fine, but GlobalLock on the handle fails only after the SetClipboardData API is called.

Step 1 : SetClipboardData(CF_UNICODETEXT, hMem) ;
Step 2 : OnClipboardUpdate
Step 3: GetClipboardData() -> GlobalLock Fail :GetLastError(6)

When calling SetClipboardData, it only fails when a handle is specified in the OpenClipboard() argument.

I want to know why GlobalLock fails.

SetClipboardData Example

if (::OpenClipboardEx(m_hViewer))
{
::EmptyClipboard();
::SetClipboardData(nFormat, hClipbd) != nullptr)
::CloseClipboard();
}

Answer 1

This test works for me in a C++/Win32 app :

TCHAR wsText[255] = TEXT("This is a test");
int nTextLength = (lstrlen(wsText) + 1) * sizeof(TCHAR);
HANDLE hClipboardData;
LPTSTR pClipboardData;
if (OpenClipboard(hWnd))
{
    hClipboardData = GlobalAlloc(GMEM_MOVEABLE | GMEM_DDESHARE, nTextLength);
    if (hClipboardData)
    {
        pClipboardData = (LPTSTR)GlobalLock(hClipboardData);
        CopyMemory(pClipboardData, wsText, nTextLength);
        GlobalUnlock(hClipboardData);                           
        EmptyClipboard();
        SetClipboardData(CF_UNICODETEXT, hClipboardData);
    }
    CloseClipboard();
}
if (OpenClipboard(hWnd))
{
    HANDLE hGlobal = GetClipboardData(CF_UNICODETEXT);
    LPTSTR pszData;
    TCHAR wsBuffer[255];
    if (hGlobal != NULL)
    {
        pszData = (LPTSTR)GlobalLock(hGlobal);
        if (NULL != pszData)
        {
            lstrcpy(wsBuffer, pszData);
            GlobalUnlock(hGlobal);
            // ...
        }
    }                       
    CloseClipboard();
}