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Demonstrate how to interrupt closing an application

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Add a menu item to the dialogs sample for simulating having unsaved
documents in the application. Then demonstrate how to do something
when the user attempts to close the application, e.g. show a dialog,
and possibly cancel closing.

This code was originally written for debugging some issue related to
closing an application, but besides that it serves as an example of a
very common pattern a lot of real world applications need in some form.

Mention the example in samples/dialogs in wxCloseEvent documentation
This commit is contained in:
Lauri Nurmi
2020-02-24 00:57:09 +02:00
committed by Vadim Zeitlin
parent d8ddf1307a
commit 1ad25bdd5c
3 changed files with 60 additions and 2 deletions
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53
samples/dialogs/dialogs.cpp
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@@ -288,6 +288,7 @@ wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
EVT_MENU(DIALOGS_STANDARD_BUTTON_SIZER_DIALOG, MyFrame::OnStandardButtonsSizerDialog)
EVT_MENU(DIALOGS_TEST_DEFAULT_ACTION, MyFrame::OnTestDefaultActionDialog)
EVT_MENU(DIALOGS_MODAL_HOOK, MyFrame::OnModalHook)
EVT_MENU(DIALOGS_SIMULATE_UNSAVED, MyFrame::OnSimulatedUnsaved)
EVT_MENU(DIALOGS_REQUEST, MyFrame::OnRequestUserAttention)
#if wxUSE_NOTIFICATION_MESSAGE
@@ -303,6 +304,7 @@ wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
#endif // wxUSE_RICHTOOLTIP
EVT_MENU(wxID_EXIT, MyFrame::OnExit)
EVT_CLOSE( MyFrame::OnClose)
wxEND_EVENT_TABLE()
#if USE_MODAL_PRESENTATION
@@ -635,6 +637,7 @@ bool MyApp::OnInit()
menuDlg->Append(DIALOGS_STANDARD_BUTTON_SIZER_DIALOG, "&Standard Buttons Sizer Dialog");
menuDlg->Append(DIALOGS_TEST_DEFAULT_ACTION, "&Test dialog default action");
menuDlg->AppendCheckItem(DIALOGS_MODAL_HOOK, "Enable modal dialog hook");
menuDlg->AppendCheckItem(DIALOGS_SIMULATE_UNSAVED, "Simulate an unsaved document at exit");
menuDlg->AppendSeparator();
menuDlg->Append(wxID_EXIT, "E&xit\tAlt-X");
@@ -678,7 +681,7 @@ bool MyApp::OnInit()
// My frame constructor
MyFrame::MyFrame(const wxString& title)
: wxFrame(NULL, wxID_ANY, title)
: wxFrame(NULL, wxID_ANY, title), m_confirmExit(false)
{
SetIcon(wxICON(sample));
@@ -2984,11 +2987,59 @@ void MyFrame::OnModalHook(wxCommandEvent& event)
s_hook.Unregister();
}
void MyFrame::OnSimulatedUnsaved(wxCommandEvent& event)
{
m_confirmExit = event.IsChecked();
}
void MyFrame::OnExit(wxCommandEvent& WXUNUSED(event) )
{
Close(true);
}
void MyFrame::OnClose(wxCloseEvent& event)
{
if ( m_confirmExit && event.CanVeto() )
{
wxMessageDialog dialog(this,
"You have an unsaved file; save before closing?",
"OnClose",
wxCENTER |
wxYES_NO | wxCANCEL |
wxICON_QUESTION);
dialog.SetYesNoLabels(
"&Save",
"&Discard changes"
);
switch ( dialog.ShowModal() )
{
case wxID_CANCEL:
event.Veto();
wxLogStatus("You cancelled closing the application.");
// Return without calling event.Skip() to prevent closing the frame.
// The application should resume operation as if closing it had not
// been attempted.
return;
case wxID_YES:
wxMessageBox("You chose to save your file.", "OnClose", wxOK);
// In a real application, do something to save the
// file(s), possibly asking for a file name and location
// using wxFileDialog.
break;
default:
wxLogError("Unexpected wxMessageDialog return code!");
wxFALLTHROUGH;
case wxID_NO:
// Don't save anything, and simply continue with closing the frame.
break;
}
}
// Continue with closing the frame.
event.Skip();
}
#if wxUSE_PROGRESSDLG
static const int max_ = 100;