Re: [PATCH v2] winex11.drv: Search for the drop target in a correct manner.

[John Found]

Ah, yes - attached is the test application I am using for the tests. It is interesting
whether such behavior is only in Windows 10 (where I tested) or on older versions as well.

If someone has an access to older windows and want to try - check what is displayed in the 
indicator label on dropping files on the popup window.

Sorry for the strange sources of the test application. :)

On Tue, 23 Apr 2019 14:21:56 +0300
John Found  wrote:
> After some more tests with a real Windows it turned, 
> that using GetAncestor() instead of GetParent() is a mistake.
>
> In fact, the popup window, owned by a window with WS_EX_ACCEPTFILES also becomes a drop target and the 
> WM_DROPFILES is sent to the **owner** window. This way the proper solution is to use exactly GetParent 
> that returns the owner window (only for the popup windows) as well.
>
> So, patch v3 is to be released soon.
>
> On Sat, 20 Apr 2019 10:20:27 +0300
> "John Found"  wrote:
> > Signed-off-by: John Found
> >
> > dlls/winex11.drv/xdnd.c | 50 ++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 42 insertions(+), 8 deletions(-)
> >
> > diff --git a/dlls/winex11.drv/xdnd.c b/dlls/winex11.drv/xdnd.c
> > index 2ab28e43bf..ac2fc644dc 100644
> > --- a/dlls/winex11.drv/xdnd.c
> > +++ b/dlls/winex11.drv/xdnd.c
> > @@ -254,6 +254,34 @@ void X11DRV_XDND_EnterEvent( HWND hWnd, XClientMessageEvent *event )
> >          XFree(xdndtypes);
> >  }
> >
> > +/* Recursively searches for a window on given coordinates in a drag&drop specific manner.
> > -
> > -
> > -
> > - Don't use WindowFromPoint instead, because it omits the STATIC and transparent
> > -
> > - windows, but they can be a valid drop targets if have WS_EX_ACCEPTFILES set.
> > - */
> >
> > +static HWND window_from_point_dnd(HWND hwnd, POINT point)
> > +{
> > - HWND child;
> > - ScreenToClient(hwnd, &point);
> > - while ((child = ChildWindowFromPointEx(hwnd, point, CWP_SKIPDISABLED | CWP_SKIPINVISIBLE)) && child != hwnd)
> > - {
> > -
> >   MapWindowPoints(hwnd, child, &point, 1);
> > -
> >   hwnd = child;
> > - }
> > -
> > - return hwnd;
> >
> > +}
> > -
> >
> > +/* Returns the first window down the hierarchy that has WS_EX_ACCEPTFILES set or
> > -
> > - returns NULL, if such window does not exists.
> > - */
> >
> > +static HWND window_accepting_files(HWND hwnd)
> > +{
> > - while (hwnd && !(GetWindowLongW(hwnd, GWL_EXSTYLE) & WS_EX_ACCEPTFILES))
> > -
> >    hwnd = GetAncestor(hwnd, GA_PARENT);
> > - return hwnd;
> >
> > +}
> > -
> >
> > /**************************************************************************
> > - X11DRV_XDND_PositionEvent
> > -
> >
> > @@ -270,7 +298,7 @@ void X11DRV_XDND_PositionEvent( HWND hWnd, XClientMessageEvent *event )
> >      HRESULT hr;
> >  XDNDxy = root_to_virtual_screen( event->data.l[2] >> 16, event->data.l[2] & 0xFFFF );
> > - targetWindow = WindowFromPoint(XDNDxy);
> > -
> >
> > targetWindow = window_from_point_dnd(hWnd, XDNDxy);
> >
> > pointl.x = XDNDxy.x;
> > pointl.y = XDNDxy.y;
> >
> > @@ -334,11 +362,15 @@ void X11DRV_XDND_PositionEvent( HWND hWnd, XClientMessageEvent *event )
> >  if (XDNDAccepted)
> >      accept = 1;
> > - else if ((GetWindowLongW( hWnd, GWL_EXSTYLE ) & WS_EX_ACCEPTFILES) &&
> > -
> >        X11DRV_XDND_HasHDROP())
> > - else
> > {
> > -
> >    accept = 1;
> > -
> >    effect = DROPEFFECT_COPY;
> > -
> >    /* fallback search for window able to accept these files. */
> > -
> > -
> >    if (window_accepting_files(targetWindow) && X11DRV_XDND_HasHDROP())
> > -
> >    {
> > -
> >        accept = 1;
> > -
> >        effect = DROPEFFECT_COPY;
> > -
> >    }
> >
> > }
> >
> > TRACE("actionRequested(%ld) accept(%d) chosen(0x%x) at x(%d),y(%d)\n",
> >
> > @@ -423,10 +455,12 @@ void X11DRV_XDND_DropEvent( HWND hWnd, XClientMessageEvent *event )
> >      {
> >          /* Only send WM_DROPFILES if Drop didn't succeed or DROPEFFECT_NONE was set.
> >           * Doing both causes winamp to duplicate the dropped files (#29081) */
> > -
> >    if ((GetWindowLongW( hWnd, GWL_EXSTYLE ) & WS_EX_ACCEPTFILES) &&
> > -
> >            X11DRV_XDND_HasHDROP())
> > -
> > -
> >    HWND hwnd_drop = window_accepting_files(window_from_point_dnd(hWnd, XDNDxy));
> > -
> > -
> >    if (hwnd_drop && X11DRV_XDND_HasHDROP())
> >    {
> > -
> >        HRESULT hr = X11DRV_XDND_SendDropFiles( hWnd );
> > -
> >        HRESULT hr = X11DRV_XDND_SendDropFiles(hwnd_drop);
> >        if (SUCCEEDED(hr))
> >        {
> >            accept = 1;
> >
> > -- 
> > 2.21.0
>
> -- 
> John Found