Don't destroy the native window in wxNativeWindow itself by default

Leave ownership of the native window to the user code as it may want to reuse
it for some other purpose and provide an explicit Disown() function that can
be called if the user really wants wxWidgets to take ownership of the native
window.

In particular, this avoids problems when using ARC under OS X which resulted
in a double "release" before.
This commit is contained in:
Vadim Zeitlin 2015-11-10 16:09:21 +01:00
parent 359f4e21be
commit cb26668204
6 changed files with 120 additions and 10 deletions

View File

@ -69,7 +69,10 @@ class WXDLLIMPEXP_CORE wxNativeWindow : public wxWindow
{
public:
// Default ctor, Create() must be called later to really create the window.
wxNativeWindow() { }
wxNativeWindow()
{
Init();
}
// Create a window from an existing native window handle.
//
@ -80,13 +83,46 @@ public:
// 0 if the handle was invalid.
wxNativeWindow(wxWindow* parent, wxWindowID winid, wxNativeWindowHandle handle)
{
Init();
Create(parent, winid, handle);
}
// Same as non-default ctor, but with a return code.
bool Create(wxWindow* parent, wxWindowID winid, wxNativeWindowHandle handle);
// By default the native window with which this wxWindow is associated is
// owned by the user code and needs to be destroyed by it in a platform
// specific way, however this function can be called to let wxNativeWindow
// dtor take care of destroying the native window instead of having to do
// it from the user code.
void Disown()
{
wxCHECK_RET( m_ownedByUser, wxS("Can't disown more than once") );
m_ownedByUser = false;
DoDisown();
}
#ifdef __WXMSW__
// Prevent the native window, not owned by us, from being destroyed by the
// base class dtor, unless Disown() had been called.
virtual ~wxNativeWindow();
#endif // __WXMSW__
private:
void Init()
{
m_ownedByUser = true;
}
// This is implemented in platform-specific code.
void DoDisown();
// If the native widget owned by the user code.
bool m_ownedByUser;
wxDECLARE_NO_COPY_CLASS(wxNativeWindow);
};

View File

@ -15,8 +15,8 @@
This class can be used as a bridge between wxWidgets and native GUI
toolkit, i.e. standard Windows controls under MSW, GTK+ widgets or Cocoa
views. Using it involves writing code specific to each platform, at the
very least for creating the native window, but possibly also to handle its
events, but this class takes care of all the generic parts.
very least for creating and destroying the native window, but possibly also
to handle its events, but this class takes care of all the generic parts.
@note Check whether @c wxHAS_NATIVE_WINDOW is defined before using this
class as it is not available under all platforms.
@ -26,14 +26,24 @@
@code
#include <wx/nativewin.h>
wxNativeWindow* switch = new wxNativeWindow(parent, wxID_ANY, gtk_switch_new());
GtkWidget* w = gtk_switch_new();
wxNativeWindow* switch = new wxNativeWindow(parent, wxID_ANY, w);
g_object_unref(w);
@endcode
and then use @c switch as usual, e.g. add it to a sizer to layout it
correctly. Of course, you will still have to use the native GTK+ functions
to handle its events and change or retrieve its state.
See the "native" page of the widgets sample for another example of using
it.
Notice that the native window still remains owned by the caller, to allow
reusing it later independently of wxWidgets. If you want wxWidgets to
delete the native window when the wxNativeWindow itself is destroyed, you
need to explicitly call Disown(). Otherwise you need to perform the
necessary cleanup in your own code by calling the appropriate
platform-specific function: under MSW, this is @c ::DestroyWindow(), under
GTK @c g_object_unref() and under Cocoa -- @c -release:.
See the "native" page of the widgets sample for the examples of using
this class under all major platforms.
@since 3.1.0
@ -76,4 +86,12 @@ public:
typically because the supplied parameters are invalid.
*/
bool Create(wxWindow* parent, wxWindowID winid, wxNativeWindowHandle handle);
/**
Indicate that the user code yields ownership of the native window.
This method can be called at most once and after calling it, the native
window will be destroyed when this wxNativeWindow object is.
*/
void Disown();
};

View File

@ -95,6 +95,16 @@ public:
(void)Create(parent, wxID_ANY, hwnd);
}
virtual ~NativeWindow()
{
// If you don't call this, you need to call DestroyWindow() later.
//
// Also notice that a HWND can't continue to exist under MSW if its
// parent its destroyed, so you may also want to reparent it under some
// other window if the parent of this window is also getting destroyed.
Disown();
}
protected:
// This code requires NMBCDROPDOWN to work, we don't really want to
// reproduce its definition here for very old compilers not having it.
@ -146,9 +156,22 @@ public:
);
#endif // GTK+ 3.6/earlier
g_object_ref_sink(widget);
(void)Create(parent, wxID_ANY, widget);
}
virtual ~NativeWindow()
{
// If you don't call this, you need to call g_object_unref() on the
// widget yourself. The advantage of this is that you don't necessarily
// have to do it right now and could keep using the native widget and
// destroy it later. But if you don't need it any longer, as is the
// case here, it's simpler to just call Disown() to let it be destroyed
// immediately.
Disown();
}
private:
wxMenu m_menu;
};
@ -185,6 +208,15 @@ public:
(void)Create(parent, wxID_ANY, v);
}
virtual ~NativeWindow()
{
// If you don't call this, you need to call -release: on the button
// manually (see the comment in wxGTK version above) if using manual
// reference counting. If you build with ARC, you must *not* call
// Disown() to let the native view be destroyed automatically.
Disown();
}
};
#else // some other platform

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@ -54,11 +54,9 @@ wxNativeWindow::Create(wxWindow* parent,
if ( !CreateBase(parent, winid) )
return false;
// Add a reference to the widget to match g_object_unref() in wxWindow dtor
// (and by using the "_sink" version we avoid memory leaks when we're
// passed a newly allocated widget, as is typically the case).
// Add a reference to the widget to match g_object_unref() in wxWindow dtor.
m_widget = widget;
g_object_ref_sink(m_widget);
g_object_ref(m_widget);
parent->DoAddChild(this);
@ -73,6 +71,11 @@ wxNativeWindow::Create(wxWindow* parent,
return true;
}
void wxNativeWindow::DoDisown()
{
g_object_unref(m_widget);
}
// ----------------------------------------------------------------------------
// wxNativeContainerWindow
// ----------------------------------------------------------------------------

View File

@ -79,6 +79,19 @@ wxNativeWindow::Create(wxWindow* parent,
return true;
}
void wxNativeWindow::DoDisown()
{
// We don't do anything here, clearing m_ownedByUser flag is enough.
}
wxNativeWindow::~wxNativeWindow()
{
// Restore the original window proc and reset HWND to 0 to prevent it from
// being destroyed in the base class dtor if it's owned by user code.
if ( m_ownedByUser )
UnsubclassWin();
}
// ----------------------------------------------------------------------------
// wxNativeContainerWindow
// ----------------------------------------------------------------------------

View File

@ -59,6 +59,9 @@ wxNativeWindow::Create(wxWindow* parent,
else if ( [view respondsToSelector:@selector(stringValue)] )
m_label = wxCFStringRef::AsString([(id)view stringValue]);
// As wxWidgets will release the view when this object is destroyed, retain
// it here to avoid destroying the view owned by the user code.
[view retain];
SetPeer(new wxWidgetCocoaImpl(this, view));
// It doesn't seem necessary to use MacPostControlCreate() here as we never
@ -66,3 +69,8 @@ wxNativeWindow::Create(wxWindow* parent,
return true;
}
void wxNativeWindow::DoDisown()
{
[GetPeer()->GetWXWidget() release];
}