From 1a7ca47a7a92945e16006ddd00adea186535cdd5 Mon Sep 17 00:00:00 2001
From: Fabian Kosmale <fabian.kosmale@qt.io>
Date: Wed, 12 Feb 2020 13:29:08 +0100
Subject: QQuickLoader: store status

This allows us to emit the change signal only when the status has
actually changed. Due to alignment restrictions, this does not even
change the size of the class.

Fixes: QTBUG-82002
Change-Id: I2192bf80e72b92108046780811c3acdab39af518
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
---
 src/quick/items/qquickloader.cpp | 93 +++++++++++++++++++++++-----------------
 1 file changed, 54 insertions(+), 39 deletions(-)

(limited to 'src/quick/items/qquickloader.cpp')

diff --git a/src/quick/items/qquickloader.cpp b/src/quick/items/qquickloader.cpp
index b389e7a11b..8c15b60712 100644
--- a/src/quick/items/qquickloader.cpp
+++ b/src/quick/items/qquickloader.cpp
@@ -55,7 +55,7 @@ static const QQuickItemPrivate::ChangeTypes watchedChanges
 
 QQuickLoaderPrivate::QQuickLoaderPrivate()
     : item(nullptr), object(nullptr), itemContext(nullptr), incubator(nullptr), updatingSize(false),
-      active(true), loadingFromSource(false), asynchronous(false)
+      active(true), loadingFromSource(false), asynchronous(false), status(computeStatus())
 {
 }
 
@@ -378,7 +378,7 @@ void QQuickLoader::setActive(bool newVal)
             d->object = nullptr;
             emit itemChanged();
         }
-        emit statusChanged();
+        d->updateStatus();
     }
     emit activeChanged();
 }
@@ -431,7 +431,7 @@ void QQuickLoader::loadFromSource()
     Q_D(QQuickLoader);
     if (d->source.isEmpty()) {
         emit sourceChanged();
-        emit statusChanged();
+        d->updateStatus();
         emit progressChanged();
         emit itemChanged();
         return;
@@ -502,7 +502,7 @@ void QQuickLoader::loadFromSourceComponent()
     Q_D(QQuickLoader);
     if (!d->component) {
         emit sourceComponentChanged();
-        emit statusChanged();
+        d->updateStatus();
         emit progressChanged();
         emit itemChanged();
         return;
@@ -618,7 +618,7 @@ void QQuickLoaderPrivate::load()
                 q, SLOT(_q_sourceLoaded()));
         QObject::connect(component, SIGNAL(progressChanged(qreal)),
                 q, SIGNAL(progressChanged()));
-        emit q->statusChanged();
+        updateStatus();
         emit q->progressChanged();
         if (loadingFromSource)
             emit q->sourceChanged();
@@ -705,7 +705,7 @@ void QQuickLoaderPrivate::incubatorStateChanged(QQmlIncubator::Status status)
         emit q->sourceChanged();
     else
         emit q->sourceComponentChanged();
-    emit q->statusChanged();
+    updateStatus();
     emit q->progressChanged();
     if (status == QQmlIncubator::Ready)
         emit q->loaded();
@@ -722,7 +722,7 @@ void QQuickLoaderPrivate::_q_sourceLoaded()
             emit q->sourceChanged();
         else
             emit q->sourceComponentChanged();
-        emit q->statusChanged();
+        updateStatus();
         emit q->progressChanged();
         emit q->itemChanged(); //Like clearing source, emit itemChanged even if previous item was also null
         disposeInitialPropertyValues(); // cleanup
@@ -740,7 +740,7 @@ void QQuickLoaderPrivate::_q_sourceLoaded()
     component->create(*incubator, itemContext);
 
     if (incubator && incubator->status() == QQmlIncubator::Loading)
-        emit q->statusChanged();
+        updateStatus();
 }
 
 /*!
@@ -787,37 +787,7 @@ QQuickLoader::Status QQuickLoader::status() const
 {
     Q_D(const QQuickLoader);
 
-    if (!d->active)
-        return Null;
-
-    if (d->component) {
-        switch (d->component->status()) {
-        case QQmlComponent::Loading:
-            return Loading;
-        case QQmlComponent::Error:
-            return Error;
-        case QQmlComponent::Null:
-            return Null;
-        default:
-            break;
-        }
-    }
-
-    if (d->incubator) {
-        switch (d->incubator->status()) {
-        case QQmlIncubator::Loading:
-            return Loading;
-        case QQmlIncubator::Error:
-            return Error;
-        default:
-            break;
-        }
-    }
-
-    if (d->object)
-        return Ready;
-
-    return d->source.isEmpty() ? Null : Error;
+    return static_cast<Status>(d->status);
 }
 
 void QQuickLoader::componentComplete()
@@ -1018,6 +988,51 @@ QV4::ReturnedValue QQuickLoaderPrivate::extractInitialPropertyValues(QQmlV4Funct
     return valuemap->asReturnedValue();
 }
 
+QQuickLoader::Status QQuickLoaderPrivate::computeStatus() const
+{
+    if (!active)
+        return QQuickLoader::Status::Null;
+
+    if (component) {
+        switch (component->status()) {
+        case QQmlComponent::Loading:
+            return QQuickLoader::Status::Loading;
+        case QQmlComponent::Error:
+            return QQuickLoader::Status::Error;
+        case QQmlComponent::Null:
+            return QQuickLoader::Status::Null;
+        default:
+            break;
+        }
+    }
+
+    if (incubator) {
+        switch (incubator->status()) {
+        case QQmlIncubator::Loading:
+            return QQuickLoader::Status::Loading;
+        case QQmlIncubator::Error:
+            return QQuickLoader::Status::Error;
+        default:
+            break;
+        }
+    }
+
+    if (object)
+        return QQuickLoader::Status::Ready;
+
+    return source.isEmpty() ? QQuickLoader::Status::Null : QQuickLoader::Status::Error;
+}
+
+void QQuickLoaderPrivate::updateStatus()
+{
+    Q_Q(QQuickLoader);
+    auto newStatus = computeStatus();
+    if (status != newStatus) {
+        status = newStatus;
+        emit q->statusChanged();
+    }
+}
+
 #include <moc_qquickloader_p.cpp>
 
 QT_END_NAMESPACE
-- 
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