WebViewEdge: Allow edge webview2 installation during runtime

Check if edge webview runtime is available in the call to
wxWebView::IsBackendAvailable() instead of only doing it during
process initialization. This allows an application to install
the Edge WebView2 Runtime during runtime and use the edge webview
afterwards without restarting the process.

include/wx/msw/private/webview_edge.h

@@ -65,7 +65,7 @@ public:
 
     ICoreWebView2Settings* GetSettings();
 
-    static int ms_isAvailable;
+    static bool ms_isInitialized;
     static wxDynamicLibrary ms_loaderDll;
 
     static bool Initialize();

include/wx/msw/webview_edge.h

@@ -122,10 +122,6 @@ public:
 
     virtual void* GetNativeBackend() const wxOVERRIDE;
 
-    // ---- Edge-specific methods
-
-    static bool IsAvailable();
-
 protected:
     virtual void DoSetPage(const wxString& html, const wxString& baseUrl) wxOVERRIDE;
 
@@ -155,6 +151,7 @@ public:
     {
         return new wxWebViewEdge(parent, id, url, pos, size, style, name);
     }
+    virtual bool IsAvailable() wxOVERRIDE;
 };
 
 #endif // wxUSE_WEBVIEW && wxUSE_WEBVIEW_EDGE && defined(__WXMSW__)

include/wx/webview.h

@@ -119,6 +119,7 @@ public:
                               const wxSize& size = wxDefaultSize,
                               long style = 0,
                               const wxString& name = wxASCII_STR(wxWebViewNameStr)) = 0;
+    virtual bool IsAvailable() { return true; }
 };
 
 WX_DECLARE_STRING_HASH_MAP(wxSharedPtr<wxWebViewFactory>, wxStringWebViewFactoryMap);

interface/wx/webview.h

@@ -220,6 +220,17 @@ public:
                               const wxSize& size = wxDefaultSize,
                               long style = 0,
                               const wxString& name = wxWebViewNameStr) = 0;
+    /**
+        Function to check if the backend is available at runtime. The
+        wxWebView implementation can use this function to check all
+        runtime requirements without trying to create a wxWebView.
+
+        @return returns @true if the backend can be used or @false if it is
+            not available during runtime.
+
+        @since 3.1.5
+    */
+    virtual bool IsAvailable();
 };
 
 /**

src/common/webview.cpp

@@ -88,7 +88,10 @@ void wxWebView::RegisterFactory(const wxString& backend,
 bool wxWebView::IsBackendAvailable(const wxString& backend)
 {
     wxStringWebViewFactoryMap::iterator iter = FindFactory(backend);
-    return iter != m_factoryMap.end();
+    if (iter != m_factoryMap.end())
+        return iter->second->IsAvailable();
+    else
+        return false;
 }
 
 // static 
@@ -111,8 +114,7 @@ void wxWebView::InitFactoryMap()
 #endif
 
 #if wxUSE_WEBVIEW_EDGE
-    if (wxWebViewEdge::IsAvailable() &&
-        m_factoryMap.find(wxWebViewBackendEdge) == m_factoryMap.end())
+    if (m_factoryMap.find(wxWebViewBackendEdge) == m_factoryMap.end())
         RegisterFactory(wxWebViewBackendEdge, wxSharedPtr<wxWebViewFactory>
         (new wxWebViewFactoryEdge));
 #endif

src/msw/webview_edge.cpp

@@ -51,7 +51,7 @@ typedef HRESULT(__stdcall *GetAvailableCoreWebView2BrowserVersionString_t)(
 CreateCoreWebView2EnvironmentWithOptions_t wxCreateCoreWebView2EnvironmentWithOptions = NULL;
 GetAvailableCoreWebView2BrowserVersionString_t wxGetAvailableCoreWebView2BrowserVersionString = NULL;
 
-int wxWebViewEdgeImpl::ms_isAvailable = -1;
+bool wxWebViewEdgeImpl::ms_isInitialized = false;
 wxDynamicLibrary wxWebViewEdgeImpl::ms_loaderDll;
 
 wxWebViewEdgeImpl::wxWebViewEdgeImpl(wxWebViewEdge* webview):
@@ -113,6 +113,9 @@ HRESULT wxWebViewEdgeImpl::OnEnvironmentCreated(
 
 bool wxWebViewEdgeImpl::Initialize()
 {
+    if (ms_isInitialized)
+        return true;
+
     if (!ms_loaderDll.Load("WebView2Loader.dll", wxDL_DEFAULT | wxDL_QUIET))
         return false;
 
@@ -126,7 +129,10 @@ bool wxWebViewEdgeImpl::Initialize()
     wxCoTaskMemPtr<wchar_t> versionStr;
     HRESULT hr = wxGetAvailableCoreWebView2BrowserVersionString(NULL, &versionStr);
     if (SUCCEEDED(hr) && versionStr)
+    {
+        ms_isInitialized = true;
         return true;
+    }
     else
         wxLogApiError("GetCoreWebView2BrowserVersionInfo", hr);
 
@@ -135,10 +141,10 @@ bool wxWebViewEdgeImpl::Initialize()
 
 void wxWebViewEdgeImpl::Uninitialize()
 {
-    if (ms_isAvailable == 1)
+    if (ms_isInitialized)
     {
         ms_loaderDll.Unload();
-        ms_isAvailable = -1;
+        ms_isInitialized = false;
     }
 }
 
@@ -349,19 +355,6 @@ ICoreWebView2Settings* wxWebViewEdgeImpl::GetSettings()
     return settings;
 }
 
-bool wxWebViewEdge::IsAvailable()
-{
-    if (wxWebViewEdgeImpl::ms_isAvailable == -1)
-    {
-        if (!wxWebViewEdgeImpl::Initialize())
-            wxWebViewEdgeImpl::ms_isAvailable = 0;
-        else
-            wxWebViewEdgeImpl::ms_isAvailable = 1;
-    }
-
-    return wxWebViewEdgeImpl::ms_isAvailable == 1;
-}
-
 wxWebViewEdge::~wxWebViewEdge()
 {
     Unbind(wxEVT_SHOW, &wxWebViewEdge::OnShow, this);
@@ -376,7 +369,7 @@ bool wxWebViewEdge::Create(wxWindow* parent,
     long style,
     const wxString& name)
 {
-    if (!IsAvailable())
+    if (!wxWebViewEdgeImpl::Initialize())
         return false;
 
     if (!wxControl::Create(parent, id, pos, size, style,
@@ -869,6 +862,14 @@ void wxWebViewEdge::DoSetPage(const wxString& html, const wxString& WXUNUSED(bas
         m_impl->m_webView->NavigateToString(html.wc_str());
 }
 
+// wxWebViewFactoryEdge
+
+bool wxWebViewFactoryEdge::IsAvailable()
+{
+    return wxWebViewEdgeImpl::Initialize();
+}
+
+
 // ----------------------------------------------------------------------------
 // Module ensuring all global/singleton objects are destroyed on shutdown.
 // ----------------------------------------------------------------------------