Implement wxClipboard::Flush() in wxGTK

Update the documentation and also add a call of Flush() to the sample.

Closes #10515.

Closes https://github.com/wxWidgets/wxWidgets/pull/1316

include/wx/gtk/clipbrd.h

@@ -53,6 +53,11 @@ public:
     // fill data with data on the clipboard (if available)
     virtual bool GetData( wxDataObject& data ) wxOVERRIDE;
 
+    // flushes the clipboard; that means that the data which is currently on
+    // clipboard will stay available even after the application exits (possibly
+    // eating memory), otherwise the clipboard will be emptied on exit
+    virtual bool Flush() wxOVERRIDE;
+
     // clears wxTheClipboard and the system's clipboard if possible
     virtual void Clear() wxOVERRIDE;
 

interface/wx/clipbrd.h

@@ -96,8 +96,8 @@ public:
         (possibly eating memory), otherwise the clipboard will be emptied on
         exit.
 
-        Currently this method is not implemented in X11-based ports, i.e.
-        wxGTK, wxX11 and wxMotif and always returns @false there.
+        Currently this method is implemented in MSW and GTK and always returns @false
+        otherwise.
 
         @return @false if the operation is unsuccessful for any reason.
     */

samples/clipboard/clipboard.cpp

@@ -50,6 +50,7 @@ public:
 
     void OnQuit(wxCommandEvent&event);
     void OnAbout(wxCommandEvent&event);
+    void OnFlush(wxCommandEvent &event);
     void OnWriteClipboardContents(wxCommandEvent&event);
     void OnUpdateUI(wxUpdateUIEvent&event);
 #if USE_ASYNCHRONOUS_CLIPBOARD_REQUEST
@@ -71,12 +72,14 @@ enum
     ID_Quit   = wxID_EXIT,
     ID_About  = wxID_ABOUT,
     ID_Write  = 100,
-    ID_Text   = 101
+    ID_Text   = 101,
+    ID_Flush  = 102
 };
 
 wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
     EVT_MENU(ID_Quit,  MyFrame::OnQuit)
     EVT_MENU(ID_About, MyFrame::OnAbout)
+    EVT_MENU(ID_Flush, MyFrame::OnFlush)
     EVT_BUTTON(ID_Write, MyFrame::OnWriteClipboardContents)
     EVT_UPDATE_UI(ID_Write, MyFrame::OnUpdateUI)
 #if USE_ASYNCHRONOUS_CLIPBOARD_REQUEST
@@ -116,6 +119,7 @@ MyFrame::MyFrame(const wxString& title)
     wxMenu *helpMenu = new wxMenu;
     helpMenu->Append(ID_About, "&About\tF1", "Show about dialog");
 
+    fileMenu->Append(ID_Flush, "Flush the clipboard" );
     fileMenu->Append(ID_Quit, "E&xit\tAlt-X", "Quit this program");
 
     // now append the freshly created menu to the menu bar...
@@ -137,6 +141,14 @@ MyFrame::MyFrame(const wxString& title)
     panel->SetSizer( main_sizer );
 }
 
+void MyFrame::OnFlush(wxCommandEvent &WXUNUSED(event))
+{
+    if ( wxTheClipboard->Flush() )
+        m_textctrl->SetValue( "Clipboard flushed successfully!!\n" );
+    else
+        m_textctrl->SetValue( "Flushing clipboard failed!!\n" );
+}
+
 void MyFrame::OnWriteClipboardContents(wxCommandEvent& WXUNUSED(event))
 {
    if (wxTheClipboard->Open())

src/gtk/clipbrd.cpp

@@ -593,6 +593,12 @@ void wxClipboard::Clear()
     m_formatSupported = false;
 }
 
+bool wxClipboard::Flush()
+{
+    gtk_clipboard_store( gtk_clipboard_get( GTKGetClipboardAtom() ) );
+    return true;
+}
+
 bool wxClipboard::Open()
 {
     wxCHECK_MSG( !m_open, false, wxT("clipboard already open") );