Add wxWindow::WXNotifyDPIChange() for wxOSX and wxGTK

This refactors the already existing code in wxOSX to make it available
in the common class and allow reusing it in wxGTK.

No changes yet.

include/wx/osx/window.h

@@ -151,7 +151,6 @@ public:
     // --------------
 
     void OnMouseEvent( wxMouseEvent &event );
-    void OnDPIChanged( wxDPIChangedEvent& event );
 
     void MacOnScroll( wxScrollEvent&event );
 

include/wx/window.h

@@ -1675,6 +1675,10 @@ public:
 #ifdef wxHAS_DPI_INDEPENDENT_PIXELS
     // Return the DPI corresponding to the given scale factor.
     static wxSize MakeDPIFromScaleFactor(double scaleFactor);
+
+    // Notify all non-top-level children of the given (typically top-level
+    // itself) window about the DPI change.
+    void WXNotifyDPIChange(double oldScaleFactor, double newScaleFactor);
 #endif // wxHAS_DPI_INDEPENDENT_PIXELS
 
 protected:

src/common/wincmn.cpp

@@ -2835,6 +2835,34 @@ wxSize wxWindowBase::MakeDPIFromScaleFactor(double scaleFactor)
     return wxDisplay::GetStdPPI()*scaleFactor;
 }
 
+namespace
+{
+
+// Send the DPI change event to all children recursively.
+void NotifyAboutDPIChange(wxWindow* win, wxDPIChangedEvent& event)
+{
+    for ( const auto child : win->GetChildren() )
+    {
+        // Top level windows will get their own WXNotifyDPIChange().
+        if ( child->IsTopLevel() )
+            continue;
+
+        NotifyAboutDPIChange(child, event);
+    }
+
+    event.SetEventObject(win);
+    win->HandleWindowEvent(event);
+}
+
+} // anonymous namespace
+void wxWindowBase::WXNotifyDPIChange(double oldScaleFactor, double newScaleFactor)
+{
+    wxDPIChangedEvent event(MakeDPIFromScaleFactor(oldScaleFactor),
+                            MakeDPIFromScaleFactor(newScaleFactor));
+
+    NotifyAboutDPIChange(static_cast<wxWindow*>(this), event);
+}
+
 // In this case logical pixels are DIPs, so we don't need to define conversion
 // to/from them (or, rather, they are already defined as trivial inline
 // functions in the header), but we do need to define conversions to/from

src/osx/cocoa/nonownedwnd.mm

@@ -674,13 +674,7 @@ static void SendFullScreenWindowEvent(NSNotification* notification, bool fullscr
                                          doubleValue];
         if (newBackingScaleFactor != oldBackingScaleFactor)
         {
-            const wxSize oldDPI = wxWindow::MakeDPIFromScaleFactor(oldBackingScaleFactor);
-            const wxSize newDPI = wxWindow::MakeDPIFromScaleFactor(newBackingScaleFactor);
-
-            wxDPIChangedEvent event(oldDPI, newDPI);
-            event.SetEventObject(wxpeer);
-            wxpeer->HandleWindowEvent(event);
-
+            wxpeer->WXNotifyDPIChange(oldBackingScaleFactor, newBackingScaleFactor);
         }
 
         NSColorSpace *newColorSpace = [theWindow colorSpace];

src/osx/window_osx.cpp

@@ -79,7 +79,6 @@
 
 wxBEGIN_EVENT_TABLE(wxWindowMac, wxWindowBase)
     EVT_MOUSE_EVENTS(wxWindowMac::OnMouseEvent)
-    EVT_DPI_CHANGED(wxWindowMac::OnDPIChanged)
 wxEND_EVENT_TABLE()
 
 #define wxMAC_DEBUG_REDRAW 0
@@ -2321,25 +2320,6 @@ void wxWindowMac::OnMouseEvent( wxMouseEvent &event )
     }
 }
 
-// propagate the dpi changed event to the subwindows
-void wxWindowMac::OnDPIChanged(wxDPIChangedEvent& event)
-{
-    wxWindowList::compatibility_iterator node = GetChildren().GetFirst();
-    while ( node )
-    {
-        // Only propagate to non-top-level windows
-        wxWindow *win = node->GetData();
-        if ( !win->IsTopLevel() )
-        {
-            wxDPIChangedEvent event2( event.GetOldDPI(), event.GetNewDPI() );
-            event2.SetEventObject(win);
-            win->GetEventHandler()->ProcessEvent(event2);
-        }
-
-        node = node->GetNext();
-    }
-}
-
 void wxWindowMac::TriggerScrollEvent( wxEventType WXUNUSED(scrollEvent) )
 {
 }