QQuickComboBox: update highlighted index on mouse hover

This is the expected behavior on desktop.

NOTE: We can no longer rely on ListView.ApplyRange, because if ListView
adjusts the content position while key navigating or scrolling, "wrong"
items may get hovered and the highlighted index gets set incorrectly
leading to a hovered->highlight->hovered loop. Therefore we force
ListView.NoHighlightRange to keep existing styles working without
modifications.

Change-Id: I57fe3de1230dd6348d01c1785cd09d4fb184d28a
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 42 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquickcombobox.cpp b/src/quicktemplates2/qquickcombobox.cpp
index 3f0d359e..f511045a 100644
--- a/src/quicktemplates2/qquickcombobox.cpp
+++ b/src/quicktemplates2/qquickcombobox.cpp
@@ -37,6 +37,7 @@
 #include "qquickcombobox_p.h"
 #include "qquickcontrol_p_p.h"
 #include "qquickabstractbutton_p.h"
+#include "qquickabstractbutton_p_p.h"
 #include "qquickpopup_p_p.h"
 
 #include <QtCore/qregexp.h>
@@ -50,6 +51,7 @@
 #include <QtQml/private/qqmldelegatemodel_p.h>
 #include <QtQuick/private/qquickevents_p_p.h>
 #include <QtQuick/private/qquicktextinput_p.h>
+#include <QtQuick/private/qquickitemview_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -221,6 +223,7 @@ public:
     void popupVisibleChanged();
 
     void itemClicked();
+    void itemHovered();
 
     void createdItem(int index, QObject *object);
     void modelUpdated();
@@ -253,6 +256,7 @@ public:
     bool hasDown;
     bool pressed;
     bool ownModel;
+    bool keyNavigating;
     bool hasDisplayText;
     bool hasCurrentIndex;
     int highlightedIndex;
@@ -291,6 +295,7 @@ QQuickComboBoxPrivate::QQuickComboBoxPrivate()
       hasDown(false),
       pressed(false),
       ownModel(false),
+      keyNavigating(false),
       hasDisplayText(false),
       hasCurrentIndex(false),
       highlightedIndex(-1),
@@ -341,7 +346,15 @@ void QQuickComboBoxPrivate::popupVisibleChanged()
     if (isPopupVisible())
         QGuiApplication::inputMethod()->reset();
 
+    QQuickItemView *itemView = popup->findChild<QQuickItemView *>();
+    if (itemView)
+        itemView->setHighlightRangeMode(QQuickItemView::NoHighlightRange);
+
     updateHighlightedIndex();
+
+    if (itemView)
+        itemView->positionViewAtIndex(highlightedIndex, QQuickItemView::Beginning);
+
     if (!hasDown) {
         q->setDown(pressed || isPopupVisible());
         hasDown = false;
@@ -358,6 +371,25 @@ void QQuickComboBoxPrivate::itemClicked()
     }
 }
 
+void QQuickComboBoxPrivate::itemHovered()
+{
+    Q_Q(QQuickComboBox);
+    if (keyNavigating)
+        return;
+
+    QQuickAbstractButton *button = qobject_cast<QQuickAbstractButton *>(q->sender());
+    if (!button || !button->isHovered() || QQuickAbstractButtonPrivate::get(button)->touchId != -1)
+        return;
+
+    int index = delegateModel->indexOf(button, nullptr);
+    if (index != -1) {
+        setHighlightedIndex(index, Highlight);
+
+        if (QQuickItemView *itemView = popup->findChild<QQuickItemView *>())
+            itemView->positionViewAtIndex(index, QQuickItemView::Contain);
+    }
+}
+
 void QQuickComboBoxPrivate::createdItem(int index, QObject *object)
 {
     Q_Q(QQuickComboBox);
@@ -371,6 +403,7 @@ void QQuickComboBoxPrivate::createdItem(int index, QObject *object)
     if (button) {
         button->setFocusPolicy(Qt::NoFocus);
         connect(button, &QQuickAbstractButton::clicked, this, &QQuickComboBoxPrivate::itemClicked);
+        connect(button, &QQuickAbstractButton::hoveredChanged, this, &QQuickComboBoxPrivate::itemHovered);
     }
 
     if (index == currentIndex && !q->isEditable())
@@ -1155,6 +1188,9 @@ void QQuickComboBox::setPopup(QQuickPopup *popup)
         QQuickPopupPrivate::get(popup)->allowVerticalFlip = true;
         popup->setClosePolicy(QQuickPopup::CloseOnEscape | QQuickPopup::CloseOnPressOutsideParent);
         QObjectPrivate::connect(popup, &QQuickPopup::visibleChanged, d, &QQuickComboBoxPrivate::popupVisibleChanged);
+
+        if (QQuickItemView *itemView = popup->findChild<QQuickItemView *>())
+            itemView->setHighlightRangeMode(QQuickItemView::NoHighlightRange);
     }
     d->popup = popup;
     emit popupChanged();
@@ -1446,14 +1482,17 @@ void QQuickComboBox::keyPressEvent(QKeyEvent *event)
         event->accept();
         break;
     case Qt::Key_Up:
+        d->keyNavigating = true;
         d->decrementCurrentIndex();
         event->accept();
         break;
     case Qt::Key_Down:
+        d->keyNavigating = true;
         d->incrementCurrentIndex();
         event->accept();
         break;
     case Qt::Key_Home:
+        d->keyNavigating = true;
         if (d->isPopupVisible())
             d->setHighlightedIndex(0, Highlight);
         else
@@ -1461,6 +1500,7 @@ void QQuickComboBox::keyPressEvent(QKeyEvent *event)
         event->accept();
         break;
     case Qt::Key_End:
+        d->keyNavigating = true;
         if (d->isPopupVisible())
             d->setHighlightedIndex(count() - 1, Highlight);
         else
@@ -1480,6 +1520,8 @@ void QQuickComboBox::keyReleaseEvent(QKeyEvent *event)
 {
     Q_D(QQuickComboBox);
     QQuickControl::keyReleaseEvent(event);
+
+    d->keyNavigating = false;
     if (!d->popup || event->isAutoRepeat())
         return;