DesignMode: Create only when needed

Postpone the Mode object creation until it is really necessary,
the private data object may be needed before.

In the QmlDesigner this patch moves the connection to the DesignMode
instance back to delayedInitialize, essentially reverting part of
e8b3b8140b.

Change-Id: I07146b0bc93eede09af8e824e916edb6de1817ef
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/coreplugin.cpp

@@ -71,7 +71,6 @@ using namespace Utils;
 CorePlugin::CorePlugin()
   : m_mainWindow(0)
   , m_editMode(0)
-  , m_designMode(0)
   , m_locator(0)
 {
     qRegisterMetaType<Id>();
@@ -90,11 +89,7 @@ CorePlugin::~CorePlugin()
         delete m_editMode;
     }
 
-    if (m_designMode) {
-        if (DesignMode::designModeIsRequired())
-            removeObject(m_designMode);
-        delete m_designMode;
-    }
+    DesignMode::destroyModeIfRequired();
 
     delete m_mainWindow;
     setCreatorTheme(0);
@@ -159,7 +154,6 @@ bool CorePlugin::initialize(const QStringList &arguments, QString *errorMessage)
         m_editMode = new EditMode;
         addObject(m_editMode);
         ModeManager::activateMode(m_editMode->id());
-        m_designMode = new DesignMode;
         InfoBar::initialize(ICore::settings(), creatorTheme());
     }
 
@@ -226,8 +220,7 @@ bool CorePlugin::initialize(const QStringList &arguments, QString *errorMessage)
 
 void CorePlugin::extensionsInitialized()
 {
-    if (DesignMode::designModeIsRequired())
-        addObject(m_designMode);
+    DesignMode::createModeIfRequired();
     Find::extensionsInitialized();
     m_locator->extensionsInitialized();
     m_mainWindow->extensionsInitialized();

src/plugins/coreplugin/coreplugin.h

@@ -38,9 +38,6 @@ class PathChooser;
 }
 
 namespace Core {
-
-class DesignMode;
-
 namespace Internal {
 
 class EditMode;
@@ -83,7 +80,6 @@ private:
 
     MainWindow *m_mainWindow;
     EditMode *m_editMode;
-    DesignMode *m_designMode;
     Locator *m_locator;
     ReaperPrivate m_reaper;
 };

src/plugins/coreplugin/designmode.cpp

@@ -29,10 +29,11 @@
 #include <coreplugin/idocument.h>
 #include <coreplugin/modemanager.h>
 #include <coreplugin/editormanager/editormanager.h>
+#include <coreplugin/editormanager/ieditor.h>
 #include <coreplugin/coreconstants.h>
 #include <coreplugin/coreicons.h>
 
-#include <coreplugin/editormanager/ieditor.h>
+#include <extensionsystem/pluginmanager.h>
 
 #include <QPointer>
 #include <QStringList>
@@ -59,7 +60,6 @@ public:
 public:
     QPointer<IEditor> m_currentEditor;
     bool m_isActive = false;
-    bool m_isRequired = false;
     QList<DesignEditorInfo*> m_editors;
     QStackedWidget *m_stackWidget;
     Context m_activeContext;
@@ -79,9 +79,6 @@ static DesignModePrivate *d = nullptr;
 
 DesignMode::DesignMode()
 {
-    m_instance = this;
-    d = new DesignModePrivate;
-
     ICore::addPreCloseListener([]() -> bool {
         m_instance->currentEditorChanged(0);
         return true;
@@ -107,7 +104,6 @@ DesignMode::DesignMode()
 DesignMode::~DesignMode()
 {
     qDeleteAll(d->m_editors);
-    delete d;
 }
 
 DesignMode *DesignMode::instance()
@@ -117,12 +113,9 @@ DesignMode *DesignMode::instance()
 
 void DesignMode::setDesignModeIsRequired()
 {
-    d->m_isRequired = true;
-}
-
-bool DesignMode::designModeIsRequired()
-{
-    return d->m_isRequired;
+    // d != nullptr indicates "isRequired".
+    if (!d)
+        d = new DesignModePrivate;
 }
 
 /**
@@ -227,4 +220,21 @@ void DesignMode::setActiveContext(const Context &context)
     d->m_activeContext = context;
 }
 
+void DesignMode::createModeIfRequired()
+{
+    if (d) {
+        m_instance = new DesignMode;
+        ExtensionSystem::PluginManager::addObject(m_instance);
+    }
+}
+
+void DesignMode::destroyModeIfRequired()
+{
+    if (m_instance) {
+        ExtensionSystem::PluginManager::removeObject(m_instance);
+        delete m_instance;
+    }
+    delete d;
+}
+
 } // namespace Core

src/plugins/coreplugin/designmode.h

@@ -42,23 +42,25 @@ class CORE_EXPORT DesignMode : public IMode
     Q_OBJECT
 
 public:
-    explicit DesignMode();
-    virtual ~DesignMode();
-
     static DesignMode *instance();
 
     static void setDesignModeIsRequired();
-    static bool designModeIsRequired();
 
     static void registerDesignWidget(QWidget *widget,
                                      const QStringList &mimeTypes,
                                      const Context &context);
     static void unregisterDesignWidget(QWidget *widget);
 
+    static void createModeIfRequired();
+    static void destroyModeIfRequired();
+
 signals:
     void actionsUpdated(Core::IEditor *editor);
 
 private:
+    DesignMode();
+    ~DesignMode() final;
+
     void updateActions();
 
     void currentEditorChanged(IEditor *editor);

src/plugins/qmldesigner/qmldesignerplugin.cpp

@@ -199,6 +199,9 @@ bool QmlDesignerPlugin::delayedInitialize()
     d->viewManager.registerFormEditorToolTakingOwnership(new QmlDesigner::TextTool);
     d->viewManager.registerFormEditorToolTakingOwnership(new QmlDesigner::PathTool);
 
+    connect(Core::DesignMode::instance(), &Core::DesignMode::actionsUpdated,
+        &d->shortCutManager, &ShortCutManager::updateActions);
+
     return true;
 }
 
@@ -253,9 +256,6 @@ void QmlDesignerPlugin::integrateIntoQtCreator(QWidget *modeWidget)
 
     Core::DesignMode::registerDesignWidget(modeWidget, mimeTypes, d->context->context());
 
-    connect(Core::DesignMode::instance(), &Core::DesignMode::actionsUpdated,
-        &d->shortCutManager, &ShortCutManager::updateActions);
-
     connect(Core::EditorManager::instance(), &Core::EditorManager::currentEditorChanged, [this] (Core::IEditor *editor) {
         if (d && checkIfEditorIsQtQuick(editor) && isInDesignerMode())
             changeEditor();