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authorMitch Curtis <mitch.curtis@qt.io>2019-09-04 14:19:48 +0200
committerMitch Curtis <mitch.curtis@qt.io>2019-10-01 17:07:32 +0200
commita392194a575653dff3cd21227e6a1a2902b8399f (patch)
treee6547b0633c99a069ffba7eb7527ca162a1b0de1
parent88b6b70c58b4c0dbd9d8217e19b9046095168277 (diff)
ComboBox: fix performance regressionv5.14.0-beta1
f4623123 introduced a performance regression by calling delegateModel->object() twice: if (componentComplete) { updateCurrentText(); updateCurrentValue(); } We can avoid this by introducing versions of these functions that take the delegate model object as a parameter in order to cache it between calls. Change-Id: I5f9041a8ff00b53e04d759f38677bd87c748f8d1 Fixes: QTBUG-76029 Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
-rw-r--r--src/quicktemplates2/qquickcombobox.cpp119
1 files changed, 95 insertions, 24 deletions
diff --git a/src/quicktemplates2/qquickcombobox.cpp b/src/quicktemplates2/qquickcombobox.cpp
index 60526a0a..21eecfe1 100644
--- a/src/quicktemplates2/qquickcombobox.cpp
+++ b/src/quicktemplates2/qquickcombobox.cpp
@@ -43,6 +43,7 @@
#include <QtCore/qregularexpression.h>
#include <QtCore/qabstractitemmodel.h>
+#include <QtCore/qglobal.h>
#include <QtGui/qinputmethod.h>
#include <QtGui/qguiapplication.h>
#include <QtGui/qpa/qplatformtheme.h>
@@ -231,6 +232,13 @@ public:
void updateEditText();
void updateCurrentText();
void updateCurrentValue();
+ void updateCurrentText(bool hasDelegateModelObject);
+ void updateCurrentValue(bool hasDelegateModelObject);
+ void updateCurrentTextAndValue();
+
+ bool isValidIndex(int index) const;
+ QString fastTextAt(int index) const;
+ QVariant fastValueAt(int index) const;
void acceptInput();
QString tryComplete(const QString &inputText);
@@ -433,10 +441,34 @@ void QQuickComboBoxPrivate::updateEditText()
q->setEditText(text);
}
+// We have these two rather than just using default arguments
+// because QObjectPrivate::connect() doesn't accept lambdas.
void QQuickComboBoxPrivate::updateCurrentText()
{
+ updateCurrentText(false);
+}
+
+void QQuickComboBoxPrivate::updateCurrentValue()
+{
+ updateCurrentValue(false);
+}
+
+void QQuickComboBoxPrivate::updateCurrentText(bool hasDelegateModelObject)
+{
Q_Q(QQuickComboBox);
- QString text = q->textAt(currentIndex);
+ QString text;
+ // If a delegate model object was passed in, it means the calling code
+ // has decided to reuse it for several function calls to speed things up.
+ // So, use the faster (private) version in that case.
+ // For other cases, we use the version that creates the delegate model object
+ // itself in order to have neater, more convenient calling code.
+ if (isValidIndex(currentIndex)) {
+ if (hasDelegateModelObject)
+ text = fastTextAt(currentIndex);
+ else
+ text = q->textAt(currentIndex);
+ }
+
if (currentText != text) {
currentText = text;
if (!hasDisplayText)
@@ -451,10 +483,19 @@ void QQuickComboBoxPrivate::updateCurrentText()
q->setEditText(currentText);
}
-void QQuickComboBoxPrivate::updateCurrentValue()
+void QQuickComboBoxPrivate::updateCurrentValue(bool hasDelegateModelObject)
{
Q_Q(QQuickComboBox);
- const QVariant value = q->valueAt(currentIndex);
+ QVariant value;
+ // If a delegate model object was passed in, it means the calling code
+ // has decided to reuse it for several function calls to speed things up.
+ // So, use the faster (private) version in that case.
+ if (isValidIndex(currentIndex)) {
+ if (hasDelegateModelObject)
+ value = fastValueAt(currentIndex);
+ else
+ value = q->valueAt(currentIndex);
+ }
if (currentValue == value)
return;
@@ -462,6 +503,38 @@ void QQuickComboBoxPrivate::updateCurrentValue()
emit q->currentValueChanged();
}
+void QQuickComboBoxPrivate::updateCurrentTextAndValue()
+{
+ QObject *object = nullptr;
+ // For performance reasons, we reuse the same delegate model object: QTBUG-76029.
+ if (isValidIndex(currentIndex))
+ object = delegateModel->object(currentIndex);
+ const bool hasDelegateModelObject = object != nullptr;
+ updateCurrentText(hasDelegateModelObject);
+ updateCurrentValue(hasDelegateModelObject);
+ if (object)
+ delegateModel->release(object);
+}
+
+bool QQuickComboBoxPrivate::isValidIndex(int index) const
+{
+ return delegateModel && index >= 0 && index < delegateModel->count();
+}
+
+// For performance reasons (QTBUG-76029), both this and valueAt assume that
+// the index is valid and delegateModel->object(index) has been called.
+QString QQuickComboBoxPrivate::fastTextAt(int index) const
+{
+ const QString effectiveTextRole = textRole.isEmpty() ? QStringLiteral("modelData") : textRole;
+ return delegateModel->stringValue(index, effectiveTextRole);
+}
+
+QVariant QQuickComboBoxPrivate::fastValueAt(int index) const
+{
+ const QString effectiveValueRole = valueRole.isEmpty() ? QStringLiteral("modelData") : valueRole;
+ return delegateModel->variantValue(index, effectiveValueRole);
+}
+
void QQuickComboBoxPrivate::acceptInput()
{
Q_Q(QQuickComboBox);
@@ -508,10 +581,8 @@ void QQuickComboBoxPrivate::setCurrentIndex(int index, Activation activate)
currentIndex = index;
emit q->currentIndexChanged();
- if (componentComplete) {
- updateCurrentText();
- updateCurrentValue();
- }
+ if (componentComplete)
+ updateCurrentTextAndValue();
if (activate)
emit q->activated(index);
@@ -832,10 +903,14 @@ void QQuickComboBox::setModel(const QVariant& m)
if (d->model == model)
return;
- if (QAbstractItemModel* aim = qvariant_cast<QAbstractItemModel *>(d->model))
- QObjectPrivate::disconnect(aim, &QAbstractItemModel::dataChanged, d, &QQuickComboBoxPrivate::updateCurrentText);
- if (QAbstractItemModel* aim = qvariant_cast<QAbstractItemModel *>(model))
- QObjectPrivate::connect(aim, &QAbstractItemModel::dataChanged, d, &QQuickComboBoxPrivate::updateCurrentText);
+ if (QAbstractItemModel* aim = qvariant_cast<QAbstractItemModel *>(d->model)) {
+ QObjectPrivate::disconnect(aim, &QAbstractItemModel::dataChanged,
+ d, QOverload<>::of(&QQuickComboBoxPrivate::updateCurrentText));
+ }
+ if (QAbstractItemModel* aim = qvariant_cast<QAbstractItemModel *>(model)) {
+ QObjectPrivate::connect(aim, &QAbstractItemModel::dataChanged,
+ d, QOverload<>::of(&QQuickComboBoxPrivate::updateCurrentText));
+ }
d->model = model;
d->createDelegateModel();
@@ -1505,15 +1580,13 @@ QVariant QQuickComboBox::currentValue() const
QVariant QQuickComboBox::valueAt(int index) const
{
Q_D(const QQuickComboBox);
- if (!d->delegateModel || index < 0 || index >= d->delegateModel->count())
+ if (!d->isValidIndex(index))
return QVariant();
- // We use QVariant because the model API uses QVariant.
- QVariant value;
QObject *object = d->delegateModel->object(index);
+ QVariant value;
if (object) {
- const QString role = d->valueRole.isEmpty() ? QStringLiteral("modelData") : d->valueRole;
- value = d->delegateModel->variantValue(index, role);
+ value = d->fastValueAt(index);
d->delegateModel->release(object);
}
return value;
@@ -1550,13 +1623,13 @@ int QQuickComboBox::indexOfValue(const QVariant &value) const
QString QQuickComboBox::textAt(int index) const
{
Q_D(const QQuickComboBox);
- if (!d->delegateModel || index < 0 || index >= d->delegateModel->count())
+ if (!d->isValidIndex(index))
return QString();
- QString text;
QObject *object = d->delegateModel->object(index);
+ QString text;
if (object) {
- text = d->delegateModel->stringValue(index, d->textRole.isEmpty() ? QStringLiteral("modelData") : d->textRole);
+ text = d->fastTextAt(index);
d->delegateModel->release(object);
}
return text;
@@ -1823,12 +1896,10 @@ void QQuickComboBox::componentComplete()
static_cast<QQmlDelegateModel *>(d->delegateModel)->componentComplete();
if (count() > 0) {
- if (!d->hasCurrentIndex && d->currentIndex == -1) {
+ if (!d->hasCurrentIndex && d->currentIndex == -1)
setCurrentIndex(0);
- } else {
- d->updateCurrentText();
- d->updateCurrentValue();
- }
+ else
+ d->updateCurrentTextAndValue();
}
}