Fix clipping of scrolled windows under macOS Sonoma

We need to use a native clip view for things to behave correctly under
this OS version, otherwise scrollbars can be overdrawn by the window
contents.

Closes #24067.

Closes #24073.

include/wx/osx/cocoa/private.h

@@ -220,8 +220,13 @@ public :
     // from the same pimpl class.
     virtual void                controlTextDidChange();
 
+    virtual void                AdjustClippingView(wxScrollBar* horizontal, wxScrollBar* vertical) override;
+    virtual void                UseClippingView(bool clip) override;
+    virtual WXWidget            GetContainer() const override { return m_osxClipView ? m_osxClipView : m_osxView; }
+
 protected:
     WXWidget m_osxView;
+    WXWidget m_osxClipView;
 
     // begins processing of native key down event, storing the native event for later wx event generation
     void BeginNativeKeyDownEvent( NSEvent* event );

include/wx/osx/core/private.h

@@ -365,6 +365,14 @@ public :
 
     virtual bool        EnableTouchEvents(int eventsMask) = 0;
 
+    // scrolling views need a clip subview that acts as parent for native children
+    // (except for the scollbars) which are children of the view itself
+    virtual void        AdjustClippingView(wxScrollBar* horizontal, wxScrollBar* vertical);
+    virtual void        UseClippingView(bool clip);
+
+    // returns native view which acts as a parent for native children
+    virtual WXWidget    GetContainer() const;
+
     // Mechanism used to keep track of whether a change should send an event
     // Do SendEvents(false) when starting actions that would trigger programmatic events
     // and SendEvents(true) at the end of the block.

include/wx/osx/window.h

@@ -224,7 +224,7 @@ public:
     // returns true if children have to clipped to the content area
     // (e.g., scrolled windows)
     bool                MacClipChildren() const { return m_clipChildren ; }
-    void                MacSetClipChildren( bool clip ) { m_clipChildren = clip ; }
+    void                MacSetClipChildren( bool clip );
 
     // returns true if the grandchildren need to be clipped to the children's content area
     // (e.g., splitter windows)

src/osx/cocoa/window.mm

@@ -16,6 +16,7 @@
     #include "wx/textctrl.h"
     #include "wx/combobox.h"
     #include "wx/radiobut.h"
+    #include "wx/scrolbar.h"
 #endif
 
 #ifdef __WXMAC__
@@ -2562,6 +2563,7 @@ wxWidgetImpl( peer, flags )
 {
     Init();
     m_osxView = w;
+    m_osxClipView = nil;
 
     // check if the user wants to create the control initially hidden
     if ( !peer->IsShown() )
@@ -3215,6 +3217,21 @@ bool wxWidgetCocoaImpl::CanFocus() const
     return canFocus;
 }
 
+@interface wxNSClipView : NSClipView
+
+@end
+
+@implementation wxNSClipView
+
+#if wxOSX_USE_NATIVE_FLIPPED
+- (BOOL)isFlipped
+{
+    return YES;
+}
+#endif
+
+@end
+
 bool wxWidgetCocoaImpl::HasFocus() const
 {
     NSView* targetView = m_osxView;
@@ -3305,7 +3322,13 @@ void wxWidgetCocoaImpl::RemoveFromParent()
 
 void wxWidgetCocoaImpl::Embed( wxWidgetImpl *parent )
 {
-    NSView* container = parent->GetWXWidget() ;
+    NSView* container = nil;
+
+    if ( m_wxPeer->MacIsWindowScrollbar( parent->GetWXPeer()))
+        container = parent->GetWXWidget();
+    else
+        container = parent->GetContainer();
+
     wxASSERT_MSG( container != nullptr , wxT("No valid mac container control") ) ;
     [container addSubview:m_osxView];
     
@@ -4034,6 +4057,41 @@ void wxWidgetCocoaImpl::SetDrawingEnabled(bool enabled)
         [[m_osxView window] disableFlushWindow];
     }
 }
+
+void wxWidgetCocoaImpl::AdjustClippingView(wxScrollBar* horizontal, wxScrollBar* vertical)
+{
+    if( m_osxClipView )
+    {
+        NSRect bounds = m_osxView.bounds;
+        if( horizontal && horizontal->IsShown() )
+        {
+            int sz = horizontal->GetSize().y;
+            bounds.size.height -= sz;
+        }
+        if( vertical && vertical->IsShown() )
+        {
+            int sz = vertical->GetSize().x;
+            bounds.size.width -= sz;
+        }
+        m_osxClipView.frame = bounds;
+    }
+}
+
+void wxWidgetCocoaImpl::UseClippingView(bool clip)
+{
+   wxWindow* peer = m_wxPeer;
+
+    if ( peer && m_osxClipView == nil)
+    {
+        m_osxClipView = [[wxNSClipView alloc] initWithFrame: m_osxView.bounds];
+        [(NSClipView*)m_osxClipView setDrawsBackground: NO];
+        [m_osxView addSubview:m_osxClipView];
+
+        // TODO check for additional subwindows which might have to be moved to the clip view ?
+    }
+}
+
+
 //
 // Factory methods
 //

src/osx/window_osx.cpp

@@ -261,6 +261,13 @@ wxWindowMac::~wxWindowMac()
     delete GetPeer() ;
 }
 
+void wxWindowMac::MacSetClipChildren( bool clip )
+{
+    m_clipChildren = clip ;
+    if ( m_peer )
+        m_peer->UseClippingView(clip);
+}
+
 WXWidget wxWindowMac::GetHandle() const
 {
     if ( GetPeer() )
@@ -386,6 +393,8 @@ bool wxWindowMac::Create(wxWindowMac *parent,
     {
         SetPeer(wxWidgetImpl::CreateUserPane( this, parent, id, pos, size , style, GetExtraStyle() ));
         MacPostControlCreate(pos, size) ;
+        if ( m_clipChildren )
+            m_peer->UseClippingView(m_clipChildren);
     }
 
     wxWindowCreateEvent event((wxWindow*)this);
@@ -2139,6 +2148,7 @@ void wxWindowMac::MacRepositionScrollBars()
                 m_growBox->Hide();
         }
     }
+    m_peer->AdjustClippingView(m_hScrollBar, m_vScrollBar);
 #endif
 }
 
@@ -2700,3 +2710,16 @@ bool wxWidgetImpl::NeedsFrame() const
 void wxWidgetImpl::SetDrawingEnabled(bool WXUNUSED(enabled))
 {
 }
+
+void wxWidgetImpl::AdjustClippingView(wxScrollBar* WXUNUSED(horizontal), wxScrollBar* WXUNUSED(vertical))
+{
+}
+
+void wxWidgetImpl::UseClippingView(bool WXUNUSED(clip))
+{
+}
+
+WXWidget wxWidgetImpl::GetContainer() const
+{
+    return GetWXWidget();
+}