Do not crash because of missing context on the indicator buttons

This now follows the same pattern as QQuickSpinBox does it for it's
own indicator buttons.

a11y::ScrollBar crashed because of this

Change-Id: I5669fa2bf130b37ad46573aae5c6bebd8e0d0434
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

2 files changed, 27 insertions, 4 deletions

diff --git a/src/quicktemplates2/qquickscrollbar.cpp b/src/quicktemplates2/qquickscrollbar.cpp
index 4c89b330..cc338b65 100644
--- a/src/quicktemplates2/qquickscrollbar.cpp
+++ b/src/quicktemplates2/qquickscrollbar.cpp
@@ -388,6 +388,9 @@ void QQuickScrollBarPrivate::updateHover(const QPointF &pos, std::optional<bool>
 QQuickScrollBar::QQuickScrollBar(QQuickItem *parent)
     : QQuickControl(*(new QQuickScrollBarPrivate), parent)
 {
+    Q_D(QQuickScrollBar);
+    d->decreaseVisual = new QQuickIndicatorButton(this);
+    d->increaseVisual = new QQuickIndicatorButton(this);
     setKeepMouseGrab(true);
     setAcceptedMouseButtons(Qt::LeftButton);
 #if QT_CONFIG(quicktemplates2_multitouch)
@@ -771,16 +774,12 @@ qreal QQuickScrollBar::visualPosition() const
 QQuickIndicatorButton *QQuickScrollBar::decreaseVisual()
 {
     Q_D(QQuickScrollBar);
-    if (!d->decreaseVisual)
-        d->decreaseVisual = new QQuickIndicatorButton(this);
     return d->decreaseVisual;
 }
 
 QQuickIndicatorButton *QQuickScrollBar::increaseVisual()
 {
     Q_D(QQuickScrollBar);
-    if (!d->increaseVisual)
-        d->increaseVisual = new QQuickIndicatorButton(this);
     return d->increaseVisual;
 }
 
@@ -855,6 +854,27 @@ void QQuickScrollBar::hoverLeaveEvent(QHoverEvent *event)
     d->updateHover(QPoint(), false);    //position is not needed when we force it to unhover
 }
 
+void QQuickScrollBar::classBegin()
+{
+    Q_D(QQuickScrollBar);
+    QQuickControl::classBegin();
+
+    QQmlContext *context = qmlContext(this);
+    if (context) {
+        QQmlEngine::setContextForObject(d->decreaseVisual, context);
+        QQmlEngine::setContextForObject(d->increaseVisual, context);
+    }
+}
+
+void QQuickScrollBar::componentComplete()
+{
+    Q_D(QQuickScrollBar);
+    QQuickIndicatorButtonPrivate::get(d->decreaseVisual)->executeIndicator(true);
+    QQuickIndicatorButtonPrivate::get(d->increaseVisual)->executeIndicator(true);
+
+    QQuickControl::componentComplete();
+}
+
 #if QT_CONFIG(accessibility)
 void QQuickScrollBar::accessibilityActiveChanged(bool active)
 {
diff --git a/src/quicktemplates2/qquickscrollbar_p.h b/src/quicktemplates2/qquickscrollbar_p.h
index b35575b9..b7de290b 100644
--- a/src/quicktemplates2/qquickscrollbar_p.h
+++ b/src/quicktemplates2/qquickscrollbar_p.h
@@ -174,6 +174,9 @@ protected:
     void hoverLeaveEvent(QHoverEvent *event) override;
 #endif
 
+    void classBegin() override;
+    void componentComplete() override;
+
 #if QT_CONFIG(accessibility)
     void accessibilityActiveChanged(bool active) override;
     QAccessible::Role accessibleRole() const override;