Label: use deferred execution

Task-number: QTBUG-50992
Change-Id: I8e626d1a0585f93cbd612aca39a1e9050f5e0ed3
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

3 files changed, 27 insertions, 4 deletions

diff --git a/src/quicktemplates2/qquicklabel.cpp b/src/quicktemplates2/qquicklabel.cpp
index d1ddfbd6..418a7834 100644
--- a/src/quicktemplates2/qquicklabel.cpp
+++ b/src/quicktemplates2/qquicklabel.cpp
@@ -38,6 +38,7 @@
 #include "qquicklabel_p_p.h"
 #include "qquickcontrol_p.h"
 #include "qquickcontrol_p_p.h"
+#include "qquickdeferredexecute_p_p.h"
 
 #include <QtQuick/private/qquickitem_p.h>
 #include <QtQuick/private/qquicktext_p.h>
@@ -155,6 +156,20 @@ QAccessible::Role QQuickLabelPrivate::accessibleRole() const
 }
 #endif
 
+static inline QString backgroundName() { return QStringLiteral("background"); }
+
+void QQuickLabelPrivate::executeBackground(bool complete)
+{
+    Q_Q(QQuickLabel);
+    if (background.wasExecuted())
+        return;
+
+    if (!background)
+        quickBeginDeferred(q, backgroundName(), background);
+    if (complete)
+        quickCompleteDeferred(q, backgroundName(), background);
+}
+
 QQuickLabel::QQuickLabel(QQuickItem *parent)
     : QQuickText(*(new QQuickLabelPrivate), parent)
 {
@@ -190,7 +205,9 @@ void QQuickLabel::setFont(const QFont &font)
 */
 QQuickItem *QQuickLabel::background() const
 {
-    Q_D(const QQuickLabel);
+    QQuickLabelPrivate *d = const_cast<QQuickLabelPrivate *>(d_func());
+    if (!d->background)
+        d->executeBackground();
     return d->background;
 }
 
@@ -200,14 +217,15 @@ void QQuickLabel::setBackground(QQuickItem *background)
     if (d->background == background)
         return;
 
-    QQuickControlPrivate::destroyDelegate(d->background, this);
+    delete d->background;
     d->background = background;
     if (background) {
         background->setParentItem(this);
         if (qFuzzyIsNull(background->z()))
             background->setZ(-1);
     }
-    emit backgroundChanged();
+    if (!d->background.isExecuting())
+        emit backgroundChanged();
 }
 
 void QQuickLabel::classBegin()
@@ -220,6 +238,7 @@ void QQuickLabel::classBegin()
 void QQuickLabel::componentComplete()
 {
     Q_D(QQuickLabel);
+    d->executeBackground(true);
     QQuickText::componentComplete();
 #if QT_CONFIG(accessibility)
     if (!d->accessibleAttached && QAccessible::isActive())
diff --git a/src/quicktemplates2/qquicklabel_p.h b/src/quicktemplates2/qquicklabel_p.h
index 04172900..c31e173b 100644
--- a/src/quicktemplates2/qquicklabel_p.h
+++ b/src/quicktemplates2/qquicklabel_p.h
@@ -60,6 +60,7 @@ class Q_QUICKTEMPLATES2_PRIVATE_EXPORT QQuickLabel : public QQuickText
     Q_OBJECT
     Q_PROPERTY(QFont font READ font WRITE setFont NOTIFY fontChanged) // override
     Q_PROPERTY(QQuickItem *background READ background WRITE setBackground NOTIFY backgroundChanged FINAL)
+    Q_CLASSINFO("DeferredPropertyNames", "background")
 
 public:
     explicit QQuickLabel(QQuickItem *parent = nullptr);
diff --git a/src/quicktemplates2/qquicklabel_p_p.h b/src/quicktemplates2/qquicklabel_p_p.h
index c24c855b..b8ad2ae7 100644
--- a/src/quicktemplates2/qquicklabel_p_p.h
+++ b/src/quicktemplates2/qquicklabel_p_p.h
@@ -49,6 +49,7 @@
 //
 
 #include <QtQuick/private/qquicktext_p_p.h>
+#include <QtQuickTemplates2/private/qquickdeferredpointer_p_p.h>
 
 #if QT_CONFIG(accessibility)
 #include <QtGui/qaccessible.h>
@@ -84,8 +85,10 @@ public:
     QAccessible::Role accessibleRole() const override;
 #endif
 
+    void executeBackground(bool complete = false);
+
     QFont font;
-    QQuickItem *background;
+    QQuickDeferredPointer<QQuickItem> background;
     QQuickAccessibleAttached *accessibleAttached;
 };