From b847623fbe2e33e228e4744e5fb4a2bde903397d Mon Sep 17 00:00:00 2001
From: Nicolas Werner <nicolas.werner@hotmail.de>
Date: Wed, 29 Dec 2021 22:46:04 +0100
Subject: [PATCH] Reduce allocations and time spent creating delegates by half

---
 src/timeline/DelegateChooser.cpp | 7 ++++---
 src/timeline/DelegateChooser.h   | 9 +++++----
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/timeline/DelegateChooser.cpp b/src/timeline/DelegateChooser.cpp
index ad734895..151510b6 100644
--- a/src/timeline/DelegateChooser.cpp
+++ b/src/timeline/DelegateChooser.cpp
@@ -53,7 +53,8 @@ DelegateChooser::setRoleValue(const QVariant &value)
 {
     if (value != roleValue_) {
         roleValue_ = value;
-        recalcChild();
+        if (isComponentComplete())
+            recalcChild();
         emit roleValueChanged();
     }
 }
@@ -96,8 +97,8 @@ void
 DelegateChooser::recalcChild()
 {
     for (const auto choice : qAsConst(choices_)) {
-        auto choiceValue = choice->roleValue();
-        if (!roleValue_.isValid() || !choiceValue.isValid() || choiceValue == roleValue_) {
+        const auto &choiceValue = choice->roleValueRef();
+        if (choiceValue == roleValue_ || (!choiceValue.isValid() && !roleValue_.isValid())) {
             if (child_) {
                 child_->setParentItem(nullptr);
                 child_ = nullptr;
diff --git a/src/timeline/DelegateChooser.h b/src/timeline/DelegateChooser.h
index 3e4b16d7..4e83fce1 100644
--- a/src/timeline/DelegateChooser.h
+++ b/src/timeline/DelegateChooser.h
@@ -25,10 +25,11 @@ public:
     Q_PROPERTY(QVariant roleValue READ roleValue WRITE setRoleValue NOTIFY roleValueChanged)
     Q_PROPERTY(QQmlComponent *delegate READ delegate WRITE setDelegate NOTIFY delegateChanged)
 
-    QQmlComponent *delegate() const;
+    [[nodiscard]] QQmlComponent *delegate() const;
     void setDelegate(QQmlComponent *delegate);
 
-    QVariant roleValue() const;
+    [[nodiscard]] QVariant roleValue() const;
+    [[nodiscard]] const QVariant &roleValueRef() const { return roleValue_; }
     void setRoleValue(const QVariant &value);
 
 signals:
@@ -53,10 +54,10 @@ public:
 
     QQmlListProperty<DelegateChoice> choices();
 
-    QVariant roleValue() const;
+    [[nodiscard]] QVariant roleValue() const;
     void setRoleValue(const QVariant &value);
 
-    QQuickItem *child() const { return child_; }
+    [[nodiscard]] QQuickItem *child() const { return child_; }
 
     void recalcChild();
     void componentComplete() override;