Add valueRole API to ComboBox

This allows the user to conveniently manage data for a role associated with
the text role. A common example of this is an enum stored in a backend with
nicely formatted text displayed to the user. Before this patch, developers
would have to write code like this:

    ComboBox {
        textRole: "text"
        onActivated: backend.modifier = model[currentIndex].value
        Component.onCompleted: currentIndex = findValue(backend.modifier)
        model: [
            { value: Qt.NoModifier, text: qsTr("No modifier") },
            { value: Qt.ShiftModifier, text: qsTr("Shift") },
            { value: Qt.ControlModifier, text: qsTr("Control") }
        ]

        function findValue(value) {
            for (var i = 0; i < model.length; ++i) {
                if (model[i].value === value)
                    return i
            }
            return -1
        }
    }

With this patch, the code becomes much simpler:

    ComboBox {
        textRole: "text"
        valueRole: "value"
        onActivated: backend.modifier = currentValue
        Component.onCompleted: currentIndex = indexOfValue(backend.modifier)
        model: [
            { value: Qt.NoModifier, text: qsTr("No modifier") },
            { value: Qt.ShiftModifier, text: qsTr("Shift") },
            { value: Qt.ControlModifier, text: qsTr("Control") }
        ]
    }

[ChangeLog][Controls][ComboBox] Added valueRole, currentValue and
indexOfValue(). These allow convenient management of data for a role
associated with the text role.

Change-Id: I0ed19bd0ba9cf6b044a8113ff1a8782d43065449
Fixes: QTBUG-73491
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquickcombobox_p.h b/src/quicktemplates2/qquickcombobox_p.h
index 75e535a9..a55541d4 100644
--- a/src/quicktemplates2/qquickcombobox_p.h
+++ b/src/quicktemplates2/qquickcombobox_p.h
@@ -86,6 +86,9 @@ class Q_QUICKTEMPLATES2_PRIVATE_EXPORT QQuickComboBox : public QQuickControl
     Q_PROPERTY(qreal implicitIndicatorWidth READ implicitIndicatorWidth NOTIFY implicitIndicatorWidthChanged FINAL REVISION 5)
     Q_PROPERTY(qreal implicitIndicatorHeight READ implicitIndicatorHeight NOTIFY implicitIndicatorHeightChanged FINAL REVISION 5)
     Q_CLASSINFO("DeferredPropertyNames", "background,contentItem,indicator,popup")
+    // 2.14 (Qt 5.14)
+    Q_PROPERTY(QVariant currentValue READ currentValue NOTIFY currentValueChanged FINAL REVISION 14)
+    Q_PROPERTY(QString valueRole READ valueRole WRITE setValueRole NOTIFY valueRoleChanged FINAL REVISION 14)
 
 public:
     explicit QQuickComboBox(QQuickItem *parent = nullptr);
@@ -114,6 +117,9 @@ public:
     QString textRole() const;
     void setTextRole(const QString &role);
 
+    QString valueRole() const;
+    void setValueRole(const QString &role);
+
     QQmlComponent *delegate() const;
     void setDelegate(QQmlComponent *delegate);
 
@@ -155,6 +161,11 @@ public:
     qreal implicitIndicatorWidth() const;
     qreal implicitIndicatorHeight() const;
 
+    // 2.14 (Qt 5.14)
+    QVariant currentValue() const;
+    Q_INVOKABLE QVariant valueAt(int index) const;
+    Q_INVOKABLE int indexOfValue(const QVariant &value) const;
+
 public Q_SLOTS:
     void incrementCurrentIndex();
     void decrementCurrentIndex();
@@ -189,6 +200,9 @@ Q_SIGNALS:
     // 2.5 (Qt 5.12)
     Q_REVISION(5) void implicitIndicatorWidthChanged();
     Q_REVISION(5) void implicitIndicatorHeightChanged();
+    // 2.14 (Qt 5.14)
+    Q_REVISION(14) void valueRoleChanged();
+    Q_REVISION(14) void currentValueChanged();
 
 protected:
     bool eventFilter(QObject *object, QEvent *event) override;