Remove QQuickStyleSelector::instance()

It was a bad idea to share the same instance, because non-thread-safe
instance() ends up being called from multiple threads. Let the style
plugins create their own instances instead, QQuickStyleSelector ctor
is not that heavy and there's no such shared state as originally was
anticipated.

Change-Id: Ie23091c6dd50f5d7abbab3b996da4471054da89a
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>

5 files changed, 38 insertions, 47 deletions

diff --git a/src/controls/qquickstyleselector.cpp b/src/controls/qquickstyleselector.cpp
index 8c67cdce..61d7136e 100644
--- a/src/controls/qquickstyleselector.cpp
+++ b/src/controls/qquickstyleselector.cpp
@@ -179,12 +179,6 @@ QUrl QQuickStyleSelector::baseUrl() const
     return d->baseUrl;
 }
 
-QQuickStyleSelector *QQuickStyleSelector::instance()
-{
-    static QQuickStyleSelector self;
-    return &self;
-}
-
 void QQuickStyleSelectorPrivate::updateSelectors()
 {
     if (!sharedData->staticSelectors.isEmpty())
diff --git a/src/controls/qquickstyleselector_p.h b/src/controls/qquickstyleselector_p.h
index 36ccf07c..64319098 100644
--- a/src/controls/qquickstyleselector_p.h
+++ b/src/controls/qquickstyleselector_p.h
@@ -69,8 +69,6 @@ public:
     void setBaseUrl(const QUrl &base);
     QUrl baseUrl() const;
 
-    static QQuickStyleSelector *instance();
-
 private:
     QUrl select(const QUrl &filePath) const;
 
diff --git a/src/imports/controls/material/qtlabsmaterialstyleplugin.cpp b/src/imports/controls/material/qtlabsmaterialstyleplugin.cpp
index ab98991a..db8b47ee 100644
--- a/src/imports/controls/material/qtlabsmaterialstyleplugin.cpp
+++ b/src/imports/controls/material/qtlabsmaterialstyleplugin.cpp
@@ -85,8 +85,8 @@ void QtLabsMaterialStylePlugin::initializeEngine(QQmlEngine *engine, const char
     Q_UNUSED(engine);
     Q_UNUSED(uri);
 
-    QQuickStyleSelector *selector = QQuickStyleSelector::instance();
-    if (selector && selector->style() == QStringLiteral("material")) {
+    QQuickStyleSelector selector;
+    if (selector.style() == QStringLiteral("material")) {
         if (QFont(QStringLiteral("Roboto")).family() == QStringLiteral("Roboto")) {
             QPlatformTheme *old = QGuiApplicationPrivate::platform_theme;
             if (old) {
diff --git a/src/imports/controls/qtlabscontrolsplugin.cpp b/src/imports/controls/qtlabscontrolsplugin.cpp
index b55bd20f..05135213 100644
--- a/src/imports/controls/qtlabscontrolsplugin.cpp
+++ b/src/imports/controls/qtlabscontrolsplugin.cpp
@@ -71,42 +71,41 @@ void QtLabsControlsPlugin::registerTypes(const char *uri)
     qmlRegisterType<QQuickControl>(uri, 1, 0, "Control");
     qmlRegisterType<QQuickPopup>(uri, 1, 0, "Popup");
 
-    // TODO: read the style from application manifest file
-    QQuickStyleSelector *selector = QQuickStyleSelector::instance();
-    selector->setBaseUrl(baseUrl());
+    QQuickStyleSelector selector;
+    selector.setBaseUrl(baseUrl());
 
-    qmlRegisterType(selector->select(QStringLiteral("/ApplicationWindow.qml")), uri, 1, 0, "ApplicationWindow");
-    qmlRegisterType(selector->select(QStringLiteral("/BusyIndicator.qml")), uri, 1, 0, "BusyIndicator");
-    qmlRegisterType(selector->select(QStringLiteral("/Button.qml")), uri, 1, 0, "Button");
-    qmlRegisterType(selector->select(QStringLiteral("/CheckBox.qml")), uri, 1, 0, "CheckBox");
-    qmlRegisterType(selector->select(QStringLiteral("/ComboBox.qml")), uri, 1, 0, "ComboBox");
-    qmlRegisterType(selector->select(QStringLiteral("/Dial.qml")), uri, 1, 0, "Dial");
-    qmlRegisterType(selector->select(QStringLiteral("/Drawer.qml")), uri, 1, 0, "Drawer");
-    qmlRegisterType(selector->select(QStringLiteral("/Frame.qml")), uri, 1, 0, "Frame");
-    qmlRegisterType(selector->select(QStringLiteral("/GroupBox.qml")), uri, 1, 0, "GroupBox");
-    qmlRegisterType(selector->select(QStringLiteral("/ItemDelegate.qml")), uri, 1, 0, "ItemDelegate");
-    qmlRegisterType(selector->select(QStringLiteral("/Label.qml")), uri, 1, 0, "Label");
-    qmlRegisterType(selector->select(QStringLiteral("/Menu.qml")), uri, 1, 0, "Menu");
-    qmlRegisterType(selector->select(QStringLiteral("/MenuItem.qml")), uri, 1, 0, "MenuItem");
-    qmlRegisterType(selector->select(QStringLiteral("/Pane.qml")), uri, 1, 0, "Pane");
-    qmlRegisterType(selector->select(QStringLiteral("/PageIndicator.qml")), uri, 1, 0, "PageIndicator");
-    qmlRegisterType(selector->select(QStringLiteral("/ProgressBar.qml")), uri, 1, 0, "ProgressBar");
-    qmlRegisterType(selector->select(QStringLiteral("/RadioButton.qml")), uri, 1, 0, "RadioButton");
-    qmlRegisterType(selector->select(QStringLiteral("/RangeSlider.qml")), uri, 1, 0, "RangeSlider");
-    qmlRegisterType(selector->select(QStringLiteral("/ScrollBar.qml")), uri, 1, 0, "ScrollBar");
-    qmlRegisterType(selector->select(QStringLiteral("/ScrollIndicator.qml")), uri, 1, 0, "ScrollIndicator");
-    qmlRegisterType(selector->select(QStringLiteral("/Slider.qml")), uri, 1, 0, "Slider");
-    qmlRegisterType(selector->select(QStringLiteral("/SpinBox.qml")), uri, 1, 0, "SpinBox");
-    qmlRegisterType(selector->select(QStringLiteral("/StackView.qml")), uri, 1, 0, "StackView");
-    qmlRegisterType(selector->select(QStringLiteral("/SwipeView.qml")), uri, 1, 0, "SwipeView");
-    qmlRegisterType(selector->select(QStringLiteral("/Switch.qml")), uri, 1, 0, "Switch");
-    qmlRegisterType(selector->select(QStringLiteral("/TabBar.qml")), uri, 1, 0, "TabBar");
-    qmlRegisterType(selector->select(QStringLiteral("/TabButton.qml")), uri, 1, 0, "TabButton");
-    qmlRegisterType(selector->select(QStringLiteral("/TextArea.qml")), uri, 1, 0, "TextArea");
-    qmlRegisterType(selector->select(QStringLiteral("/TextField.qml")), uri, 1, 0, "TextField");
-    qmlRegisterType(selector->select(QStringLiteral("/ToolBar.qml")), uri, 1, 0, "ToolBar");
-    qmlRegisterType(selector->select(QStringLiteral("/ToolButton.qml")), uri, 1, 0, "ToolButton");
-    qmlRegisterType(selector->select(QStringLiteral("/Tumbler.qml")), uri, 1, 0, "Tumbler");
+    qmlRegisterType(selector.select(QStringLiteral("/ApplicationWindow.qml")), uri, 1, 0, "ApplicationWindow");
+    qmlRegisterType(selector.select(QStringLiteral("/BusyIndicator.qml")), uri, 1, 0, "BusyIndicator");
+    qmlRegisterType(selector.select(QStringLiteral("/Button.qml")), uri, 1, 0, "Button");
+    qmlRegisterType(selector.select(QStringLiteral("/CheckBox.qml")), uri, 1, 0, "CheckBox");
+    qmlRegisterType(selector.select(QStringLiteral("/ComboBox.qml")), uri, 1, 0, "ComboBox");
+    qmlRegisterType(selector.select(QStringLiteral("/Dial.qml")), uri, 1, 0, "Dial");
+    qmlRegisterType(selector.select(QStringLiteral("/Drawer.qml")), uri, 1, 0, "Drawer");
+    qmlRegisterType(selector.select(QStringLiteral("/Frame.qml")), uri, 1, 0, "Frame");
+    qmlRegisterType(selector.select(QStringLiteral("/GroupBox.qml")), uri, 1, 0, "GroupBox");
+    qmlRegisterType(selector.select(QStringLiteral("/ItemDelegate.qml")), uri, 1, 0, "ItemDelegate");
+    qmlRegisterType(selector.select(QStringLiteral("/Label.qml")), uri, 1, 0, "Label");
+    qmlRegisterType(selector.select(QStringLiteral("/Menu.qml")), uri, 1, 0, "Menu");
+    qmlRegisterType(selector.select(QStringLiteral("/MenuItem.qml")), uri, 1, 0, "MenuItem");
+    qmlRegisterType(selector.select(QStringLiteral("/Pane.qml")), uri, 1, 0, "Pane");
+    qmlRegisterType(selector.select(QStringLiteral("/PageIndicator.qml")), uri, 1, 0, "PageIndicator");
+    qmlRegisterType(selector.select(QStringLiteral("/ProgressBar.qml")), uri, 1, 0, "ProgressBar");
+    qmlRegisterType(selector.select(QStringLiteral("/RadioButton.qml")), uri, 1, 0, "RadioButton");
+    qmlRegisterType(selector.select(QStringLiteral("/RangeSlider.qml")), uri, 1, 0, "RangeSlider");
+    qmlRegisterType(selector.select(QStringLiteral("/ScrollBar.qml")), uri, 1, 0, "ScrollBar");
+    qmlRegisterType(selector.select(QStringLiteral("/ScrollIndicator.qml")), uri, 1, 0, "ScrollIndicator");
+    qmlRegisterType(selector.select(QStringLiteral("/Slider.qml")), uri, 1, 0, "Slider");
+    qmlRegisterType(selector.select(QStringLiteral("/SpinBox.qml")), uri, 1, 0, "SpinBox");
+    qmlRegisterType(selector.select(QStringLiteral("/StackView.qml")), uri, 1, 0, "StackView");
+    qmlRegisterType(selector.select(QStringLiteral("/SwipeView.qml")), uri, 1, 0, "SwipeView");
+    qmlRegisterType(selector.select(QStringLiteral("/Switch.qml")), uri, 1, 0, "Switch");
+    qmlRegisterType(selector.select(QStringLiteral("/TabBar.qml")), uri, 1, 0, "TabBar");
+    qmlRegisterType(selector.select(QStringLiteral("/TabButton.qml")), uri, 1, 0, "TabButton");
+    qmlRegisterType(selector.select(QStringLiteral("/TextArea.qml")), uri, 1, 0, "TextArea");
+    qmlRegisterType(selector.select(QStringLiteral("/TextField.qml")), uri, 1, 0, "TextField");
+    qmlRegisterType(selector.select(QStringLiteral("/ToolBar.qml")), uri, 1, 0, "ToolBar");
+    qmlRegisterType(selector.select(QStringLiteral("/ToolButton.qml")), uri, 1, 0, "ToolButton");
+    qmlRegisterType(selector.select(QStringLiteral("/Tumbler.qml")), uri, 1, 0, "Tumbler");
 }
 
 void QtLabsControlsPlugin::initializeEngine(QQmlEngine *engine, const char *uri)
diff --git a/src/imports/controls/universal/qtlabsuniversalstyleplugin.cpp b/src/imports/controls/universal/qtlabsuniversalstyleplugin.cpp
index 72dca8e8..703da011 100644
--- a/src/imports/controls/universal/qtlabsuniversalstyleplugin.cpp
+++ b/src/imports/controls/universal/qtlabsuniversalstyleplugin.cpp
@@ -82,8 +82,8 @@ void QtLabsUniversalStylePlugin::registerTypes(const char *uri)
 
 void QtLabsUniversalStylePlugin::initializeEngine(QQmlEngine *engine, const char *uri)
 {
-    QQuickStyleSelector *selector = QQuickStyleSelector::instance();
-    if (selector && selector->style() == QStringLiteral("universal")) {
+    QQuickStyleSelector selector;
+    if (selector.style() == QStringLiteral("universal")) {
         if (QFont(QStringLiteral("Segoe UI")).family() == QStringLiteral("Segoe UI")) {
             QPlatformTheme *old = QGuiApplicationPrivate::platform_theme;
             if (old) {