Generate wxDPIChangedEvent when DPI changes

include/wx/event.h

@@ -641,6 +641,7 @@ class WXDLLIMPEXP_FWD_CORE wxMenuEvent;
 class WXDLLIMPEXP_FWD_CORE wxContextMenuEvent;
 class WXDLLIMPEXP_FWD_CORE wxSysColourChangedEvent;
 class WXDLLIMPEXP_FWD_CORE wxDisplayChangedEvent;
+class WXDLLIMPEXP_FWD_CORE wxDPIChangedEvent;
 class WXDLLIMPEXP_FWD_CORE wxQueryNewPaletteEvent;
 class WXDLLIMPEXP_FWD_CORE wxPaletteChangedEvent;
 class WXDLLIMPEXP_FWD_CORE wxJoystickEvent;
@@ -793,6 +794,7 @@ wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_MENU_HIGHLIGHT, wxMenuEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_CONTEXT_MENU, wxContextMenuEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_SYS_COLOUR_CHANGED, wxSysColourChangedEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_DISPLAY_CHANGED, wxDisplayChangedEvent);
+wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_DPI_CHANGED, wxDPIChangedEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_QUERY_NEW_PALETTE, wxQueryNewPaletteEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_PALETTE_CHANGED, wxPaletteChangedEvent);
 wxDECLARE_EXPORTED_EVENT(WXDLLIMPEXP_CORE, wxEVT_JOY_BUTTON_DOWN, wxJoystickEvent);
@@ -3044,6 +3046,32 @@ public:
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxDisplayChangedEvent(*this); }
 };
 
+/*
+ wxEVT_DPI_CHANGED
+ */
+class WXDLLIMPEXP_CORE wxDPIChangedEvent : public wxEvent
+{
+public:
+    explicit
+    wxDPIChangedEvent(const wxSize& oldDPI = wxDefaultSize,
+                      const wxSize& newDPI = wxDefaultSize)
+        : wxEvent(0, wxEVT_DPI_CHANGED),
+          m_oldDPI(oldDPI),
+          m_newDPI(newDPI)
+        { }
+
+    wxSize GetOldDPI() const { return m_oldDPI; }
+    wxSize GetNewDPI() const { return m_newDPI; }
+
+    virtual wxEvent *Clone() const wxOVERRIDE { return new wxDPIChangedEvent(*this); }
+
+private:
+    wxSize m_oldDPI;
+    wxSize m_newDPI;
+
+    wxDECLARE_DYNAMIC_CLASS_NO_ASSIGN(wxDPIChangedEvent);
+};
+
 /*
  wxEVT_PALETTE_CHANGED
  */
@@ -4121,6 +4149,7 @@ typedef void (wxEvtHandler::*wxDropFilesEventFunction)(wxDropFilesEvent&);
 typedef void (wxEvtHandler::*wxInitDialogEventFunction)(wxInitDialogEvent&);
 typedef void (wxEvtHandler::*wxSysColourChangedEventFunction)(wxSysColourChangedEvent&);
 typedef void (wxEvtHandler::*wxDisplayChangedEventFunction)(wxDisplayChangedEvent&);
+typedef void (wxEvtHandler::*wxDPIChangedEventFunction)(wxDPIChangedEvent&);
 typedef void (wxEvtHandler::*wxUpdateUIEventFunction)(wxUpdateUIEvent&);
 typedef void (wxEvtHandler::*wxCloseEventFunction)(wxCloseEvent&);
 typedef void (wxEvtHandler::*wxShowEventFunction)(wxShowEvent&);
@@ -4184,6 +4213,8 @@ typedef void (wxEvtHandler::*wxPressAndTapEventFunction)(wxPressAndTapEvent&);
     wxEVENT_HANDLER_CAST(wxSysColourChangedEventFunction, func)
 #define wxDisplayChangedEventHandler(func) \
     wxEVENT_HANDLER_CAST(wxDisplayChangedEventFunction, func)
+#define wxDPIChangedEventHandler(func) \
+    wxEVENT_HANDLER_CAST(wxDPIChangedEventFunction, func)
 #define wxUpdateUIEventHandler(func) \
     wxEVENT_HANDLER_CAST(wxUpdateUIEventFunction, func)
 #define wxCloseEventHandler(func) \
@@ -4443,6 +4474,7 @@ typedef void (wxEvtHandler::*wxPressAndTapEventFunction)(wxPressAndTapEvent&);
 #define EVT_INIT_DIALOG(func)  wx__DECLARE_EVT0(wxEVT_INIT_DIALOG, wxInitDialogEventHandler(func))
 #define EVT_SYS_COLOUR_CHANGED(func) wx__DECLARE_EVT0(wxEVT_SYS_COLOUR_CHANGED, wxSysColourChangedEventHandler(func))
 #define EVT_DISPLAY_CHANGED(func)  wx__DECLARE_EVT0(wxEVT_DISPLAY_CHANGED, wxDisplayChangedEventHandler(func))
+#define EVT_DPI_CHANGED(func)  wx__DECLARE_EVT0(wxEVT_DPI_CHANGED, wxDPIChangedEventHandler(func))
 #define EVT_SHOW(func) wx__DECLARE_EVT0(wxEVT_SHOW, wxShowEventHandler(func))
 #define EVT_MAXIMIZE(func) wx__DECLARE_EVT0(wxEVT_MAXIMIZE, wxMaximizeEventHandler(func))
 #define EVT_ICONIZE(func) wx__DECLARE_EVT0(wxEVT_ICONIZE, wxIconizeEventHandler(func))

include/wx/msw/window.h

@@ -587,7 +587,8 @@ public:
     virtual void WXDoUpdatePendingFocus(wxWindow* WXUNUSED(win)) {}
 
     // Called from WM_DPICHANGED handler for all windows to let them update
-    // any sizes and fonts used internally when the DPI changes.
+    // any sizes and fonts used internally when the DPI changes and generate
+    // wxDPIChangedEvent to let the user code do the same thing as well.
     void MSWUpdateOnDPIChange(const wxSize& oldDPI, const wxSize& newDPI);
 
 protected:

interface/wx/event.h

@@ -3318,6 +3318,62 @@ public:
 };
 
 
+
+/**
+    @class wxDPIChangedEvent
+
+    Event sent when the resolution (measured in dots-per-inch, or DPI) of the
+    monitor a window is on changes.
+
+    The event is sent to each wxTopLevelWindow affected by the change, and all
+    its children recursively. For example, this event is sent to the window
+    when it is moved, by the user, from a display using some DPI value to
+    another display using a different DPI value. It also sent to all program
+    windows on the given display if its DPI changes due to a change in the
+    system settings.
+
+    Currently this event is generated by wxMSW port if only and only if the
+    MSW application runs under Windows 10 Creators Update (v1703) or later and
+    is marked as being "per-monitor DPI aware", i.e. contains a @c dpiAwareness
+    tag with the value "PerMonitorV2" in its manifest (see Microsoft
+    <a href="https://docs.microsoft.com/en-us/windows/desktop/sbscs/application-manifests">"Application Manifests" documentation</a>
+    for more details).
+
+    @note Per-monitor DPI support is an experimental feature that is still in
+    development. It might not work correctly for some controls.
+
+    @beginEventTable{wxDPIChangedEvent}
+    @event{EVT_DPI_CHANGED(func)}
+        Process a @c wxEVT_DPI_CHANGED event.
+    @endEventTable
+
+    @since 3.1.3
+
+    @library{wxcore}
+    @category{events}
+
+    @see @ref overview_events
+*/
+class wxDPIChangedEvent : public wxEvent
+{
+public:
+    /**
+        Returns the old DPI.
+
+        @since 3.1.3
+    */
+    wxSize GetOldDPI() const;
+
+    /**
+        Returns the new DPI.
+
+        @since 3.1.3
+    */
+    wxSize GetNewDPI() const;
+};
+
+
+
 class wxPaletteChangedEvent : public wxEvent
 {
 public:

interface/wx/window.h

@@ -2044,7 +2044,7 @@ public:
 
         If the DPI is not available, returns @c wxSize(0,0) object.
 
-        @see wxDisplay::GetPPI()
+        @see wxDisplay::GetPPI(), wxDPIChangedEvent
 
         @since 3.1.3
      */

src/common/event.cpp

@@ -92,6 +92,7 @@
     wxIMPLEMENT_DYNAMIC_CLASS(wxSetCursorEvent, wxEvent);
     wxIMPLEMENT_DYNAMIC_CLASS(wxSysColourChangedEvent, wxEvent);
     wxIMPLEMENT_DYNAMIC_CLASS(wxDisplayChangedEvent, wxEvent);
+    wxIMPLEMENT_DYNAMIC_CLASS(wxDPIChangedEvent, wxEvent);
     wxIMPLEMENT_DYNAMIC_CLASS(wxUpdateUIEvent, wxCommandEvent);
     wxIMPLEMENT_DYNAMIC_CLASS(wxNavigationKeyEvent, wxEvent);
     wxIMPLEMENT_DYNAMIC_CLASS(wxPaletteChangedEvent, wxEvent);
@@ -302,6 +303,7 @@ wxDEFINE_EVENT( wxEVT_MENU_HIGHLIGHT, wxMenuEvent );
 wxDEFINE_EVENT( wxEVT_CONTEXT_MENU, wxContextMenuEvent );
 wxDEFINE_EVENT( wxEVT_SYS_COLOUR_CHANGED, wxSysColourChangedEvent );
 wxDEFINE_EVENT( wxEVT_DISPLAY_CHANGED, wxDisplayChangedEvent );
+wxDEFINE_EVENT( wxEVT_DPI_CHANGED, wxDPIChangedEvent );
 wxDEFINE_EVENT( wxEVT_QUERY_NEW_PALETTE, wxQueryNewPaletteEvent );
 wxDEFINE_EVENT( wxEVT_PALETTE_CHANGED, wxPaletteChangedEvent );
 wxDEFINE_EVENT( wxEVT_JOY_BUTTON_DOWN, wxJoystickEvent );

src/msw/window.cpp

@@ -4876,6 +4876,10 @@ wxWindowMSW::MSWUpdateOnDPIChange(const wxSize& oldDPI, const wxSize& newDPI)
 
         current = current->GetNext();
     }
+
+    wxDPIChangedEvent event(oldDPI, newDPI);
+    event.SetEventObject(this);
+    HandleWindowEvent(event);
 }
 
 // ---------------------------------------------------------------------------