QComboBox: add property placeholderText

QComboBox had no option to tell the user that he must select an item -
there was no placeholder text like e.g. in QLineEdit. This feature is
widely used in html forms so we should support it also.
Therefore add a new property 'placeholderText' to specify a text which
should be shown when the current selected index is invalid.

[ChangeLog][QtWidgets][QComboBox] QComboBox got a new property
'placeholderText'

Change-Id: If6dac45c9f43455474e267907b0b0d893301c611
Fixes: QTBUG-1556
Fixes: QTBUG-2776
Fixes: QTBUG-77141
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/auto/widgets/widgets/qcombobox/tst_qcombobox.cpp b/tests/auto/widgets/widgets/qcombobox/tst_qcombobox.cpp
index eed4fe3539..cab13092cb 100644
--- a/tests/auto/widgets/widgets/qcombobox/tst_qcombobox.cpp
+++ b/tests/auto/widgets/widgets/qcombobox/tst_qcombobox.cpp
@@ -397,6 +397,31 @@ void tst_QComboBox::getSetCheck()
     QCOMPARE(4, obj1.currentIndex()); // Valid
     obj1.setCurrentIndex(INT_MAX);
     QCOMPARE(-1, obj1.currentIndex()); // Invalid => -1
+
+    obj1.setIconSize(QSize(64, 32));
+    QCOMPARE(obj1.iconSize(), QSize(64, 32));
+    obj1.setIconSize(QSize());
+    const int iconWidth = obj1.style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, &obj1);
+    QCOMPARE(obj1.iconSize(), QSize(iconWidth, iconWidth));
+
+    const QString placeholderText("Please select");
+    obj1.setCurrentIndex(1);
+    obj1.setPlaceholderText(placeholderText);
+    QCOMPARE(obj1.placeholderText(), placeholderText);
+    QCOMPARE(obj1.currentText(), "2");
+    QCOMPARE(obj1.currentIndex(), 1);
+    obj1.setPlaceholderText(QString()); // should not change anything
+    QCOMPARE(obj1.placeholderText(), QString());
+    QCOMPARE(obj1.currentText(), "2");
+
+    obj1.clear();
+    obj1.setPlaceholderText(placeholderText);
+    obj1.addItems({"1", "2", "3", "4", "5"});
+    QCOMPARE(obj1.currentText(), placeholderText);
+    QCOMPARE(obj1.currentIndex(), -1);
+    obj1.setPlaceholderText(QString()); // should not change anything
+    QCOMPARE(obj1.currentText(), "1");
+    QCOMPARE(obj1.currentIndex(), 0);
 }
 
 typedef QList<QVariant> VariantList;