Delay looking for examples until the information is needed.

E.g. when showing the example or tutorial browser.

Change-Id: I938d38872c455bbfc6f28b759701e84cd57bf354
Reviewed-by: Daniel Molkentin <daniel.molkentin@nokia.com>

src/plugins/qtsupport/exampleslistmodel.cpp

@@ -54,7 +54,9 @@ namespace Internal {
 
 ExamplesListModel::ExamplesListModel(QObject *parent) :
     QAbstractListModel(parent),
-    m_updateOnQtVersionsChanged(false)
+    m_updateOnQtVersionsChanged(false),
+    m_initialized(false),
+    m_helpInitialized(false)
 {
     QHash<int, QByteArray> roleNames;
     roleNames[Name] = "name";
@@ -382,12 +384,13 @@ void ExamplesListModel::addItems(const QList<ExampleItem> &newItems)
 
 int ExamplesListModel::rowCount(const QModelIndex &) const
 {
+    ensureInitialized();
     return exampleItems.size();
 }
 
 QVariant ExamplesListModel::data(const QModelIndex &index, int role) const
 {
-
+    ensureInitialized();
     if (!index.isValid() || index.row()+1 > exampleItems.count()) {
         qDebug() << Q_FUNC_INFO << "invalid index requested";
         return QVariant();
@@ -433,16 +436,33 @@ QVariant ExamplesListModel::data(const QModelIndex &index, int role) const
 
 }
 
-void ExamplesListModel::helpInitialized()
+QStringList ExamplesListModel::tags() const
 {
-    updateExamples();
+    ensureInitialized();
+    return m_tags;
 }
 
+void ExamplesListModel::helpInitialized()
+{
+    m_helpInitialized = true;
+    if (m_initialized) // if we are already initialized we need to update nevertheless
+        updateExamples();
+}
 
-ExamplesListModelFilter::ExamplesListModelFilter(QObject *parent) :
-    QSortFilterProxyModel(parent), m_showTutorialsOnly(true)
+void ExamplesListModel::ensureInitialized() const
+{
+    if (m_initialized || !m_helpInitialized)
+        return;
+    ExamplesListModel *that = const_cast<ExamplesListModel *>(this);
+    that->m_initialized = true;
+    that->updateExamples();
+}
+
+ExamplesListModelFilter::ExamplesListModelFilter(ExamplesListModel *sourceModel, QObject *parent) :
+    QSortFilterProxyModel(parent), m_showTutorialsOnly(true), m_sourceModel(sourceModel)
 {
     connect(this, SIGNAL(showTutorialsOnlyChanged()), SLOT(updateFilter()));
+    setSourceModel(m_sourceModel);
 }
 
 void ExamplesListModelFilter::updateFilter()
@@ -510,6 +530,18 @@ bool ExamplesListModelFilter::filterAcceptsRow(int sourceRow, const QModelIndex
     return true;
 }
 
+int ExamplesListModelFilter::rowCount(const QModelIndex &parent) const
+{
+    m_sourceModel->ensureInitialized();
+    return QSortFilterProxyModel::rowCount(parent);
+}
+
+QVariant ExamplesListModelFilter::data(const QModelIndex &index, int role) const
+{
+    m_sourceModel->ensureInitialized();
+    return QSortFilterProxyModel::data(index, role);
+}
+
 void ExamplesListModelFilter::setShowTutorialsOnly(bool showTutorialsOnly)
 {
     m_showTutorialsOnly = showTutorialsOnly;

src/plugins/qtsupport/exampleslistmodel.h

@@ -69,14 +69,15 @@ class ExamplesListModel : public QAbstractListModel {
     Q_OBJECT
 public:
     explicit ExamplesListModel(QObject *parent);
-    void addItems(const QList<ExampleItem> &items);
 
     virtual int rowCount(const QModelIndex &parent = QModelIndex()) const;
     virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
 
-    QStringList tags() const { return m_tags; }
+    QStringList tags() const;
 
 
+    void ensureInitialized() const;
+
 signals:
     void tagsUpdated();
 
@@ -86,6 +87,7 @@ public slots:
     void helpInitialized();
 
 private:
+    void addItems(const QList<ExampleItem> &items);
     QList<ExampleItem> parseExamples(QXmlStreamReader* reader, const QString& projectsOffset);
     QList<ExampleItem> parseDemos(QXmlStreamReader* reader, const QString& projectsOffset);
     QList<ExampleItem> parseTutorials(QXmlStreamReader* reader, const QString& projectsOffset);
@@ -95,6 +97,8 @@ private:
     QList<ExampleItem> exampleItems;
     QStringList m_tags;
     bool m_updateOnQtVersionsChanged;
+    bool m_initialized;
+    bool m_helpInitialized;
 };
 
 class ExamplesListModelFilter : public QSortFilterProxyModel {
@@ -104,7 +108,7 @@ public:
     Q_PROPERTY(QStringList filterTags READ filterTags WRITE setFilterTags NOTIFY filterTagsChanged)
     Q_PROPERTY(QStringList searchStrings READ searchStrings WRITE setSearchStrings NOTIFY searchStrings)
 
-    explicit ExamplesListModelFilter(QObject *parent);
+    explicit ExamplesListModelFilter(ExamplesListModel *sourceModel, QObject *parent);
 
     bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const;
 
@@ -112,6 +116,9 @@ public:
     QStringList filterTags() const { return m_filterTags; }
     QStringList searchStrings() const { return m_searchString; }
 
+    virtual int rowCount(const QModelIndex &parent = QModelIndex()) const;
+    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
+
 public slots:
     void setFilterTags(const QStringList& arg)
     {
@@ -145,6 +152,7 @@ private:
     bool m_showTutorialsOnly;
     QStringList m_filterTags;
     QStringList m_searchString;
+    ExamplesListModel *m_sourceModel;
 };
 
 } // namespace Internal

src/plugins/qtsupport/gettingstartedwelcomepage.cpp

@@ -267,8 +267,7 @@ void ExamplesWelcomePage::facilitateQml(QDeclarativeEngine *engine)
     m_engine = engine;
     m_engine->addImageProvider(QLatin1String("helpimage"), new HelpImageProvider);
     connect (examplesModel(), SIGNAL(tagsUpdated()), SLOT(updateTagsModel()));
-    ExamplesListModelFilter *proxy = new ExamplesListModelFilter(this);
-    proxy->setSourceModel(examplesModel());
+    ExamplesListModelFilter *proxy = new ExamplesListModelFilter(examplesModel(), this);
 
     proxy->setDynamicSortFilter(true);
     proxy->sort(0);