Convert sample from platform SDK to Delphi

[ste_ett]

"this" is a pointer to the current instance of the class.

"(LPVOID)" turns the pointer from a pointer to a class into a normal pointer.

[Remko]

Not sure I understand what you mean. Can you show me the Delphi translation?

[ste_ett]

Delphi-Quellcode:

m_hwndHidden := CreateWindowEx(  ...,
                            ...,


                                Self);

[Remko]

Thanks Stefan, you confirm what I made of it. On to the next one

[Robert Marquardt]

The conversion of "(LPVOID) this" is "Pointer(Self)". _HiddenWindowProc receives a WM_CREATE message where the LParam points to a CREATESTRUCT structure. The lpCreateParams element of that structure is the value handed to CreateWindowEx. This allows to jump back into object land inside of _HiddenWindowProc function by casting the pointer back and then having access to the object again.

[Remko]

Thanks Robert, that makes it clear. (I understand now that I didn't take the most easy example to start with for a first conversion, but I'm learning not also the conversion itself but a lot more! But hey, I guess it's Luctor et Emergo!)

[Remko]

Just posting some progress (attached). I'm currently stuck at _HiddenWindowProc()

Code:

   CPropSheetHost *pThis = (CPropSheetHost*)((LONG_PTR)GetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET));

    switch (uMessage)
    {
    case WM_NCCREATE:
        {
            LPCREATESTRUCT lpcs = (LPCREATESTRUCT)lParam;
            pThis = (CPropSheetHost*)(lpcs->lpCreateParams);
            ::SetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET, (LONG)(LONG_PTR)pThis);

I'm going to stop for the moment, I was obviously too optimistic I'd be able to finish it today. Fröhliche Weihnachten und ein glückliches Neues Jahr to everyone here.

[Robert Marquardt]

Code:

   CPropSheetHost *pThis = (CPropSheetHost*)((LONG_PTR)GetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET));

This is a local variable which is immediately initialized. GetWindowLongPtr supersedes GetWindowLong. You can use GetWindowLong instead.
The value pulled is the this or Self value handed in as parameter to CreateWindowEx.

Code:

    switch (uMessage)
    {
    case WM_NCCREATE:
        {
            LPCREATESTRUCT lpcs = (LPCREATESTRUCT)lParam;
            pThis = (CPropSheetHost*)(lpcs->lpCreateParams);
            ::SetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET, (LONG)(LONG_PTR)pThis);

Now here the value is extracted from the CREATESTRUCT structure and stuffed into the extra data area of the window.
This works because WM_NCCREATE is about the first message received so the above variable initialization almost always pulls the value.
It just fails for WM_NCCREATE itself where it gets an uninitialized value, but in this case the variable is initialized from the CREATESTRUCT.
It is a bit overcoded and it contains a bug. The code is not 64 bit safe. (LONG)(LONG_PTR) is a double typecast which first casts the pointer to the type LONG_PTR. LONG_PTR can hold a 64 bit value. Unfortunately it is then casted to LONG which can hold only 32 bits. So the second typecast is actually a bug.

So this is just a trick to be always able to return to object land each time _HiddenWindowProc is called with a message.

Delphi-Quellcode:

var
  Form: TForm1; // or whatever type you have handed in to CreateWindowEx
begin
  Form := GetWindowLong(hWnd, VIEW_POINTER_OFFSET));
  case Msg of
    WM_NCCREATE:
      SetWindowLong(hWnd, VIEW_POINTER_OFFSET, LONG(LPCREATESTRUCT(lParam).lpCreateParams));

This is the trick in Delphi. You can of course drop all this and just access the global variable Form1 Delphi has created for you already.

[Remko]

OK, so:

Code:

LRESULT CALLBACK CPropSheetHost::_HiddenWindowProc( HWND hWnd,
                                                    UINT uMessage,
                                                    WPARAM wParam,
                                                    LPARAM lParam)
{
    CPropSheetHost *pThis = (CPropSheetHost*)((LONG_PTR)GetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET));

    switch (uMessage)
    {
    case WM_NCCREATE:
        {
            LPCREATESTRUCT lpcs = (LPCREATESTRUCT)lParam;
            pThis = (CPropSheetHost*)(lpcs->lpCreateParams);
            ::SetWindowLongPtr(hWnd, VIEW_POINTER_OFFSET, (LONG)(LONG_PTR)pThis);
        }
        break;

    case WM_CREATE:
        break;

    case WM_DESTROY:
        break;

    case WM_ADSPROP_NOTIFY_CHANGE:
        OutputDebugString(TEXT("WM_ADSPROP_NOTIFY_CHANGE\n"));
        break;

    case WM_DSA_SHEET_CREATE_NOTIFY:
        {
            PDSA_SEC_PAGE_INFO pSecPageInfo;
            
            // Extract the secondary sheet information from the wParam.
            if(S_OK == pThis->_ExtractSecPageInfo(wParam, &pSecPageInfo))
            {
                // Create a secondary property sheet.
                pThis->_CreateSecondaryPropertySheet(pSecPageInfo);
            }
            else
            {
                // Even if the extraction failed, the wParam needs to be freed.
                pSecPageInfo = (PDSA_SEC_PAGE_INFO)wParam;
            }

            /*
            The receiver of the  message must free the DSA_SEC_PAGE_INFO 
            structure when it is no longer needed.
            */
            LocalFree(pSecPageInfo);
        }
        return 0;

    case WM_DSA_SHEET_CLOSE_NOTIFY:
        if(PROP_SHEET_HOST_ID == wParam)
        {
            OutputDebugString(TEXT("PROP_SHEET_HOST_ID\n"));
        }
        return 0;

    default:
        break;
    }

    return DefWindowProc(hWnd, uMessage, wParam, lParam);
}

Delphi-Quellcode:

function TPropSheetHost._HiddenWindowProc(hWnd: HWnd; Msg: UINT; WParam: WPARAM; LParam: LPARAM): UINT; stdcall;
var lpcs: TCreateStruct;
  PropSheetHost: TPropSheetHost;
  pSecPageInfo: PDSA_SEC_PAGE_INFO;
  begin
  PropSheetHost := TPropSheetHost(GetWindowLong(hWnd, VIEW_POINTER_OFFSET));
  case Msg of
    WM_NCCREATE: SetWindowLong(hWnd, VIEW_POINTER_OFFSET, LONG(LPCREATESTRUCT(lParam).lpCreateParams));
    WM_CREATE:;
    WM_DESTROY:;
    WM_ADSPROP_NOTIFY_CHANGE: OutputDebugString('WM_ADSPROP_NOTIFY_CHANGE'#10#13);
    WM_DSA_SHEET_CREATE_NOTIFY:
    begin
      // Extract the secondary sheet information from the wParam.
      if _ExtractSecPageInfo(wParam, pSecPageInfo) = S_OK then
      begin
        // Create a secondary property sheet.
        _CreateSecondaryPropertySheet(pSecPageInfo);
      end
      else begin
        // Even if the extraction failed, the wParam needs to be freed.
        pSecPageInfo := PDSA_SEC_PAGE_INFO(wParam);
      end;
      {*
      The receiver of the  message must free the DSA_SEC_PAGE_INFO
      structure when it is no longer needed.
      *}
      LocalFree(Cardinal(pSecPageInfo));
      Result := 0;
      Exit;
    end;
    WM_DSA_SHEET_CLOSE_NOTIFY:
    begin
      if PROP_SHEET_HOST_ID = wParam then
      begin
        OutputDebugString('PROP_SHEET_HOST_ID'#10#13);
      end;
      Result := 0;
    end;
  end;
  Result := DefWindowProc(hWnd, Msg, wParam, lParam);
end;

[Remko]

Is this translation correct?

Code:

HRESULT CPropSheetHost::_AddPagesForObject(IADs *padsObject)
{
    HRESULT hr;
    
    // Get a copy of our IDataObject.
    CComPtr<IDataObject> spDataObject;
    hr = this->QueryInterface(IID_IDataObject, (LPVOID*)&spDataObject);
    if(FAILED(hr))
    {
        return hr;
    }
    < CUT >

Delphi-Quellcode:

function TPropSheetHost._AddPagesForObject(hPage: HPROPSHEETPAGE; lParam: LPARAM): HRESULT;
var hr: HResult;
 spDataObject: IDataObject;

begin
  // Get a copy of our IDataObject.
  spDataObject := CreateComObject(IID_IDataObject) as IDataObject;
  hr := QueryInterface(IID_IDataObject, spDataObject);
  if Failed(hr) then
  begin
    Result := hr;
    Exit;
  end;
    < CUT >

Some other questions:
How to cast a WideString to PAnsiChar? //Edit: PAnsiChar := PChar(String(WideString));

Code:

    // Fill out the PROPSHEETHEADER structure.
    psh.dwSize           = sizeof(PROPSHEETHEADER);
    psh.dwFlags          = PSH_DEFAULT;
    psh.hwndParent       = m_hwndParent;
    psh.hInstance        = NULL;
    psh.pszIcon          = NULL;
    psh.pszCaption       = W2T(sbstrTemp);
    psh.nPages           = (UINT)m_rgPageHandles.GetSize();
    psh.phpage           = m_rgPageHandles.GetData();
    psh.pfnCallback      = NULL;

GetSize returns number of elements in array? --> psh.nPages := Length(m_rgPageHandles.GetSize)?
Getdata stores all members in a pointer? How to do this in Delphi? psh.u3.phpage := @m_rgPageHandles;?

Edit: adding one more question, how to convert this:

Code:

            LPBYTE pDest = (LPBYTE)*ppSecPageInfo;
            LPBYTE pSource = (LPBYTE)wParam;

            // Copy the original memory to the new block.
            CopyMemory(pDest + dwOffset, pSource, sizeOldSize);

This part CopyMemory(pDest + dwOffset will not work in Delphi. // EDIT: CopyMemory(PChar(pDest) + dwOffset, pSource, sizeOldSize); ?

Added code so far as attachment