I can not drag a panel to an empty wxAuiNotebook from another wxAuiNotebook

[asmwarrior]

I'm using wxWidgets 3.2.4 and Windows 10 64bit, running the wxAui sample project.

If I have two wxAuiNotebook, and both of them are not empty, I can drag the panel between those wxAuiNotebooks if the style option: wxAUI_NB_TAB_EXTERNAL_MOVE is enabled.

See below image shot:

Now, if the target wxAuiNotebook get empty. I mean there is NO tabs in the target wxAuiNotebook, now I can not drag a panel to this empty wxAuiNotebook, is this by design?

See below image:

Any ideas? Thanks.

[asmwarrior]

Another question is that when the drag happens between two wxAuiNotebooks, how do I know where is the source of the wxAuiNotebook, and where is the destination of the target wxAuiNotebook? I mean currently, I don't see the wxAuiNotebookEvent class brings such information. Any ideas? Thanks.

I add three functions in the wxAui sample code

    EVT_AUINOTEBOOK_BEGIN_DRAG(wxID_ANY, MyFrame::OnNotebookBeginDrag)
    EVT_AUINOTEBOOK_END_DRAG(wxID_ANY, MyFrame::OnNotebookEndDrag)
    EVT_AUINOTEBOOK_DRAG_DONE(wxID_ANY, MyFrame::OnNotebookDragDone)

I can catch an event when the cross wxAuiNotebook drag done in the MyFrame::OnNotebookDragDone, but I see that

void MyFrame::OnNotebookDragDone(wxAuiNotebookEvent &event)
{
    wxAuiNotebook* dragSource = event.GetDragSource(); 

    int dropTarget = event.GetSelection(); 

    event.Skip();
}

The dragSource is always 0x0 in my test case.

BTW: I can not catch the other events(EVT_AUINOTEBOOK_BEGIN_DRAG and EVT_AUINOTEBOOK_END_DRAG) in my test case. I can only catch a EVT_AUINOTEBOOK_DRAG_DONE event.

[asmwarrior]

OK, I just debugged a while(I'm debugging with release version of wx from msys2, so when building the aui demo sample, I have to add the option -femit-class-debug-always), and I found that the wxAuiNotebookEvent event brings a pointer to the source wxAuiNotebook, see below image shot:

So, there is only source wxAuiNotebook pointer, I event can't figure out which panel is dragged from the source notbook to the target notebook.

[trogmaniac]

Did you check how the internal code does it?

wxWidgets/src/aui/auibook.cpp

Line 2737 in 6f62907

wxWindow* tab_ctrl = ::wxFindWindowAtPoint(mouse_screen_pt);

[asmwarrior]

Did you check how the internal code does it?

wxWidgets/src/aui/auibook.cpp

Line 2737 in 6f62907

wxWindow* tab_ctrl = ::wxFindWindowAtPoint(mouse_screen_pt);

Hi, thanks for the reply.

It looks like if there is NO tabs in the wxAuiNotebook control, the drag will do nothing?

wxWidgets/src/aui/auibook.cpp

Lines 2732 to 2748 in 6f62907

	m_curPage = src_tabs->GetActivePage();
	// check for an external move
	if (m_flags & wxAUI_NB_TAB_EXTERNAL_MOVE)
	{
	wxWindow* tab_ctrl = ::wxFindWindowAtPoint(mouse_screen_pt);
	while (tab_ctrl)
	{
	if (wxDynamicCast(tab_ctrl, wxAuiTabCtrl))
	break;
	tab_ctrl = tab_ctrl->GetParent();
	}
	if (tab_ctrl)
	{
	wxAuiNotebook* nb = (wxAuiNotebook*)tab_ctrl->GetParent();

Here, the tab_ctrl will be nullptr?

[trogmaniac]

Did you check how the internal code does it?

wxWidgets/src/aui/auibook.cpp

Line 2737 in 6f62907

wxWindow* tab_ctrl = ::wxFindWindowAtPoint(mouse_screen_pt);

Hi, thanks for the reply.

It looks like if there is NO tabs in the wxAuiNotebook control, the drag will do nothing?

wxWidgets/src/aui/auibook.cpp

Lines 2732 to 2748 in 6f62907

	m_curPage = src_tabs->GetActivePage();
	// check for an external move
	if (m_flags & wxAUI_NB_TAB_EXTERNAL_MOVE)
	{
	wxWindow* tab_ctrl = ::wxFindWindowAtPoint(mouse_screen_pt);
	while (tab_ctrl)
	{
	if (wxDynamicCast(tab_ctrl, wxAuiTabCtrl))
	break;
	tab_ctrl = tab_ctrl->GetParent();
	}
	if (tab_ctrl)
	{
	wxAuiNotebook* nb = (wxAuiNotebook*)tab_ctrl->GetParent();

Here, the tab_ctrl will be nullptr?

That pointer is for the whole tab control, if none is found at the mouse position, nothing will happen (as expected).

[asmwarrior]

The problem here is that I would like to drag an one panel from one notebook to another notebook. But the target notebook is empty, so I do not how how to do it. Maybe wx library should handle such situation?

[trogmaniac]

I would agree that this is supposed to work. If dragging into a non-empty notebook works, dragging into an empty one should work, too.

Technically the problem is that the wxTabFrame gets destroyed when the last panel is removed.

wxWidgets/src/aui/auibook.cpp

Line 3000 in 5ef4c10

void wxAuiNotebook::RemoveEmptyTabFrames()

I don't know why this is done, maybe you could just try to comment this out, and see what happens. Or the code that checks for a dropped notebook page has to create a new wxTabFrame when there is none.

[vadz]

This looks like something that just hasn't been implemented. OTOH it seems pretty weird to have an empty notebook in the first place, I think a better UI would be to avoid this somehow (e.g. by destroying it entirely -- and then providing some way to recreate it later if needed).