Add wxEVT_WEBVIEW_CREATED for wxWebViewChromium async creation

wxWebViewChromium creation is asynchronous and the object can't be
really used until OnAfterCreated() is called, so expose this in the
public API via a new event sent when the object becomes actually usable.

As a side effect, add a convenient wxWebViewEvent ctor taking wxWebView
as argument and calling SetEventObject() itself, instead of forcing all
code creating wxWebViewEvents to do it.

include/wx/webview.h

@@ -333,6 +333,9 @@ protected:
     void SendScriptResult(void* clientData, bool success,
         const wxString& output) const;
 
+    // Send wxEVT_WEBVIEW_CREATED event. This function is MT-safe.
+    void NotifyWebViewCreated();
+
 private:
     static void InitFactoryMap();
     static wxStringWebViewFactoryMap::iterator FindFactory(const wxString &backend);
@@ -377,6 +380,12 @@ class WXDLLIMPEXP_WEBVIEW wxWebViewEvent : public wxNotifyEvent
 public:
     wxWebViewEvent() = default;
 
+    wxWebViewEvent(wxWebView& webview, wxEventType type)
+        : wxNotifyEvent(type, webview.GetId())
+    {
+        SetEventObject(&webview);
+    }
+
     wxWebViewEvent(wxEventType type, int id, const wxString& url,
                    const wxString target,
                    wxWebViewNavigationActionFlags flags = wxWEBVIEW_NAV_ACTION_NONE,
@@ -405,6 +414,7 @@ private:
     wxDECLARE_DYNAMIC_CLASS_NO_ASSIGN_DEF_COPY(wxWebViewEvent);
 };
 
+wxDECLARE_EXPORTED_EVENT( WXDLLIMPEXP_WEBVIEW, wxEVT_WEBVIEW_CREATED, wxWebViewEvent );
 wxDECLARE_EXPORTED_EVENT( WXDLLIMPEXP_WEBVIEW, wxEVT_WEBVIEW_NAVIGATING, wxWebViewEvent );
 wxDECLARE_EXPORTED_EVENT( WXDLLIMPEXP_WEBVIEW, wxEVT_WEBVIEW_NAVIGATED, wxWebViewEvent );
 wxDECLARE_EXPORTED_EVENT( WXDLLIMPEXP_WEBVIEW, wxEVT_WEBVIEW_LOADED, wxWebViewEvent );
@@ -423,6 +433,10 @@ typedef void (wxEvtHandler::*wxWebViewEventFunction)
 #define wxWebViewEventHandler(func) \
     wxEVENT_HANDLER_CAST(wxWebViewEventFunction, func)
 
+#define EVT_WEBVIEW_CREATED(id, fn) \
+    wx__DECLARE_EVT1(wxEVT_WEBVIEW_CREATED, id, \
+                     wxWebViewEventHandler(fn))
+
 #define EVT_WEBVIEW_NAVIGATING(id, fn) \
     wx__DECLARE_EVT1(wxEVT_WEBVIEW_NAVIGATING, id, \
                      wxWebViewEventHandler(fn))

interface/wx/webview.h

@@ -904,6 +904,11 @@ public:
     @c scheme:///C:/example/docs.zip;protocol=zip/main.htm
 
     @beginEventEmissionTable{wxWebViewEvent}
+    @event{EVT_WEBVIEW_CREATED(id, func)}
+       Process a @c wxEVT_WEBVIEW_CREATED event, generated when the object is
+       fully initialized. For the backends using asynchronous initialization,
+       such as wxWebViewChromium, most of this class member functions can be
+       only used once this event is received.
     @event{EVT_WEBVIEW_NAVIGATING(id, func)}
        Process a @c wxEVT_WEBVIEW_NAVIGATING event, generated before trying
        to get a resource. This event may be vetoed to prevent navigating to this
@@ -967,6 +972,12 @@ public:
 
     /**
         Creation function for two-step creation.
+
+        Please note that the object creation may be asynchronous when using
+        some backends (currently this is the case only for wxWebViewChromium)
+        and the object is not really created until wxEVT_WEBVIEW_CREATED event
+        is received, so any non-trivial calls to its member functions should be
+        delayed until then.
     */
     virtual bool Create(wxWindow* parent,
                         wxWindowID id,
@@ -999,6 +1010,10 @@ public:
 
     /**
         Factory function to create a new wxWebView using a wxWebViewFactory.
+
+        Note that the returned object may not be immediately usable yet, see
+        Create() and wxEVT_WEBVIEW_CREATED.
+
         @param parent Parent window for the control
         @param id ID of this control
         @param url Initial URL to load
@@ -1785,6 +1800,11 @@ public:
     wxWebView objects.
 
     @beginEventEmissionTable{wxWebViewEvent}
+    @event{EVT_WEBVIEW_CREATED(id, func)}
+       Process a @c wxEVT_WEBVIEW_CREATED event, generated when the object is
+       fully initialized. For the backends using asynchronous initialization,
+       such as wxWebViewChromium, most of this class member functions can be
+       only used once this event is received.
     @event{EVT_WEBVIEW_NAVIGATING(id, func)}
        Process a @c wxEVT_WEBVIEW_NAVIGATING event, generated before trying
        to get a resource. This event may be vetoed to prevent navigating to this
@@ -1911,6 +1931,7 @@ public:
 };
 
 
+wxEventType wxEVT_WEBVIEW_CREATED;
 wxEventType wxEVT_WEBVIEW_NAVIGATING;
 wxEventType wxEVT_WEBVIEW_NAVIGATED;
 wxEventType wxEVT_WEBVIEW_LOADED;

samples/webview/webview.cpp

@@ -475,8 +475,8 @@ WebFrame::WebFrame(const wxString& url, bool isMain, wxWebViewWindowFeatures* wi
 
         // Chromium backend can't be used immediately after creation, so wait
         // until the browser is created before calling GetUserAgent().
-        m_browser->Bind(wxEVT_CREATE, [this](wxWindowCreateEvent& event) {
-            wxLogMessage("User Agent: %s", m_browser->GetUserAgent());
+        m_browser->Bind(wxEVT_WEBVIEW_CREATED, [this](wxWebViewEvent& event) {
+            wxLogMessage("Web view created, user agent is \"%s\"", m_browser->GetUserAgent());
 
             event.Skip();
         });
@@ -1398,7 +1398,7 @@ void WebFrame::OnAddUserScript(wxCommandEvent & WXUNUSED(evt))
 
 void WebFrame::OnSetCustomUserAgent(wxCommandEvent& WXUNUSED(evt))
 {
-    wxString customUserAgent = "Mozilla/5.0 (iPhone; CPU iPhone OS 13_1_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.1 Mobile/15E148 Safari/604.1";
+    wxString customUserAgent = m_browser->GetUserAgent();
     wxTextEntryDialog dialog
     (
         this,

src/common/webview.cpp

@@ -45,6 +45,7 @@ extern WXDLLIMPEXP_DATA_WEBVIEW(const char) wxWebViewBackendDefault[] = "wxWebVi
 wxIMPLEMENT_ABSTRACT_CLASS(wxWebView, wxControl);
 wxIMPLEMENT_DYNAMIC_CLASS(wxWebViewEvent, wxCommandEvent);
 
+wxDEFINE_EVENT( wxEVT_WEBVIEW_CREATED, wxWebViewEvent );
 wxDEFINE_EVENT( wxEVT_WEBVIEW_NAVIGATING, wxWebViewEvent );
 wxDEFINE_EVENT( wxEVT_WEBVIEW_NAVIGATED, wxWebViewEvent );
 wxDEFINE_EVENT( wxEVT_WEBVIEW_LOADED, wxWebViewEvent );
@@ -446,6 +447,13 @@ wxWebView* wxWebView::New(wxWindow* parent, wxWindowID id, const wxString& url,
 
 }
 
+void wxWebView::NotifyWebViewCreated()
+{
+    GetEventHandler()->QueueEvent(
+        new wxWebViewEvent{*this, wxEVT_WEBVIEW_CREATED}
+    );
+}
+
 // static
 void wxWebView::RegisterFactory(const wxString& backend,
                                 wxSharedPtr<wxWebViewFactory> factory)

src/common/webview_chromium.cpp

@@ -1012,6 +1012,8 @@ void ClientHandler::OnAfterCreated(CefRefPtr<CefBrowser> browser)
         m_browserId = browser->GetIdentifier();
 
         m_webview.PostSizeEvent();
+
+        m_webview.NotifyWebViewCreated();
     }
 }
 bool ClientHandler::DoClose(CefRefPtr<CefBrowser> WXUNUSED(browser))

src/gtk/webview_webkit.cpp

@@ -508,6 +508,8 @@ bool wxWebViewWebKit::Create(wxWindow *parent,
                            G_CALLBACK(wxgtk_webview_webkit_load_status),
                            this);
 
+    NotifyWebViewCreated();
+
     return true;
 }
 

src/gtk/webview_webkit2.cpp

@@ -907,6 +907,8 @@ bool wxWebViewWebKit::Create(wxWindow *parent,
 
     PostCreation(size);
 
+    NotifyWebViewCreated();
+
     /* Open a webpage */
     if (!isChildWebView)
         webkit_web_view_load_uri(m_web_view, url.utf8_str());

src/msw/webview_edge.cpp

@@ -1033,6 +1033,8 @@ bool wxWebViewEdge::Create(wxWindow* parent,
     if (topLevelParent)
         topLevelParent->Bind(wxEVT_ICONIZE, &wxWebViewEdge::OnTopLevelParentIconized, this);
 
+    NotifyWebViewCreated();
+
     LoadURL(url);
     return true;
 }

src/msw/webview_ie.cpp

@@ -109,6 +109,8 @@ bool wxWebViewIE::Create(wxWindow* parent,
     // pages without any physical network connection.
     SetOfflineMode(false);
 
+    NotifyWebViewCreated();
+
     LoadURL(url);
     return true;
 }

src/osx/webview_webkit.mm

@@ -321,6 +321,8 @@ bool wxWebViewWebKit::Create(wxWindow *parent,
 
     m_UIDelegate = uiDelegate;
 
+    NotifyWebViewCreated();
+
     if (m_request)
         [m_webView loadRequest:(NSURLRequest*)m_request];
     else