[PATCH] winex11.drv: Allow the children windows to accept WM_DROPFILES if they have WS_EX_ACCEPTFILES.

[John Found]

Wine-bug: https://bugs.winehq.org/show_bug.cgi?id=41606
Signed-off-by: John Found 
---
 dlls/winex11.drv/xdnd.c | 58 +++++++++++++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 8 deletions(-)

diff --git a/dlls/winex11.drv/xdnd.c b/dlls/winex11.drv/xdnd.c
index 2ab28e43bf..2ba98491e1 100644
--- a/dlls/winex11.drv/xdnd.c
+++ b/dlls/winex11.drv/xdnd.c
@@ -254,6 +254,31 @@ void X11DRV_XDND_EnterEvent( HWND hWnd, XClientMessageEvent *event )
         XFree(xdndtypes);
 }

+/* the recursive worker for window_from_point_dnd */
+HWND do_window_from_point_dnd(HWND hwnd, POINT* point)
+{
+    HWND w;
+    w = ChildWindowFromPointEx(hwnd, *point, CWP_SKIPDISABLED | CWP_SKIPINVISIBLE);
+    if (w && (w != hwnd))
+    {
+        ClientToScreen(hwnd, point);
+        ScreenToClient(w, point);
+        w = do_window_from_point_dnd(w, point);
+    }
+    return w;
+}
+
+
+/* Recursively search for the window on given coordinates in a drag&drop specific manner. */
+HWND window_from_point_dnd(HWND hwnd, POINT point)
+{
+    POINT p;
+    p.x = point.x;
+    p.y = point.y;
+    ScreenToClient(hwnd, &p);
+    return do_window_from_point_dnd(hwnd, &p);
+}
+
 /**************************************************************************
  * X11DRV_XDND_PositionEvent
  *
@@ -270,7 +295,7 @@ 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 +359,18 @@ 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. */
+
+        while (targetWindow && !(GetWindowLongW(targetWindow, GWL_EXSTYLE) & WS_EX_ACCEPTFILES))
+            targetWindow = GetParent(targetWindow);
+
+        if (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 +455,20 @@ 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())
+        POINT pt;
+        HWND hwnd_drop;
+
+        pt.x = XDNDxy.x;
+        pt.y = XDNDxy.y;
+
+        hwnd_drop = window_from_point_dnd(hWnd, pt);
+
+        while (hwnd_drop && !(GetWindowLongW(hwnd_drop, GWL_EXSTYLE) & WS_EX_ACCEPTFILES))
+            hwnd_drop = GetParent(hwnd_drop);
+
+        if (hwnd_drop)
         {
-            HRESULT hr = X11DRV_XDND_SendDropFiles( hWnd );
+            HRESULT hr = X11DRV_XDND_SendDropFiles(hwnd_drop);
             if (SUCCEEDED(hr))
             {
                 accept = 1;

[Alexandre Julliard]

John Found  writes:
> +HWND do_window_from_point_dnd(HWND hwnd, POINT* point)
> +{
> - HWND w;
> - w = ChildWindowFromPointEx(hwnd, *point, CWP_SKIPDISABLED | CWP_SKIPINVISIBLE);
> - if (w && (w != hwnd))
> - {
> -
>    ClientToScreen(hwnd, point);
> -
>    ScreenToClient(w, point);

MapWindowPoints() would be more efficient.
> -
>    w = do_window_from_point_dnd(w, point);
> - }
> - return w;
>
> +}
> -
> -
>
> +/* Recursively search for the window on given coordinates in a drag&drop specific manner. */
> +HWND window_from_point_dnd(HWND hwnd, POINT point)
> +{
> - POINT p;
> - p.x = point.x;
> - p.y = point.y;
> - ScreenToClient(hwnd, &p);
> - return do_window_from_point_dnd(hwnd, &p);
>
> +}

There's no need to make it recursive.
> @@ -423,10 +455,20 @@ 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())
> -
>    POINT pt;
> -
>    HWND hwnd_drop;
> -
> -
>    pt.x = XDNDxy.x;
> -
>    pt.y = XDNDxy.y;
> -
> -
>    hwnd_drop = window_from_point_dnd(hWnd, pt);
> -
> -
>    while (hwnd_drop && !(GetWindowLongW(hwnd_drop, GWL_EXSTYLE) & WS_EX_ACCEPTFILES))
> -
>        hwnd_drop = GetParent(hwnd_drop);
> -
> -
>    if (hwnd_drop)

You are losing the X11DRV_XDND_HasHDROP() check. If that's deliberate,
it should be a separate patch.

[John Found]

On Fri, 20 Jul 2018 16:43:02 +0200
Alexandre Julliard  wrote:
> John Found  writes:
> > +HWND do_window_from_point_dnd(HWND hwnd, POINT* point)
> > +{
> > - HWND w;
> > - w = ChildWindowFromPointEx(hwnd, *point, CWP_SKIPDISABLED | CWP_SKIPINVISIBLE);
> > - if (w && (w != hwnd))
> > - {
> > -
> >    ClientToScreen(hwnd, point);
> > -
> >    ScreenToClient(w, point);
>
> MapWindowPoints() would be more efficient.

Will use it. Thanks.
> > -
> >    w = do_window_from_point_dnd(w, point);
> > - }
> > - return w;
> >
> > +}
> > -
> > -
> >
> > +/* Recursively search for the window on given coordinates in a drag&drop specific manner. */
> > +HWND window_from_point_dnd(HWND hwnd, POINT point)
> > +{
> > - POINT p;
> > - p.x = point.x;
> > - p.y = point.y;
> > - ScreenToClient(hwnd, &p);
> > - return do_window_from_point_dnd(hwnd, &p);
> >
> > +}
>
> There's no need to make it recursive.

How about if the target is a window deep inside the parent-child tree? Actually the recursive search is the very essence of this patch. ChildWindowFromPointEx searches only immediate children of the window. Or I am missing something?
> > @@ -423,10 +455,20 @@ 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())
> > -
> >    POINT pt;
> > -
> >    HWND hwnd_drop;
> > -
> > -
> >    pt.x = XDNDxy.x;
> > -
> >    pt.y = XDNDxy.y;
> > -
> > -
> >    hwnd_drop = window_from_point_dnd(hWnd, pt);
> > -
> > -
> >    while (hwnd_drop && !(GetWindowLongW(hwnd_drop, GWL_EXSTYLE) & WS_EX_ACCEPTFILES))
> > -
> >        hwnd_drop = GetParent(hwnd_drop);
> > -
> > -
> >    if (hwnd_drop)
>
> You are losing the X11DRV_XDND_HasHDROP() check. If that's deliberate,
> it should be a separate patch.

It is my fault. Will fix it.
> -- 
> Alexandre Julliard
> [e-mail]