Accept ZWNJ, ZWJ and PUA characters in input widgets

Private Use Area characters are quite valid input characters when used
in combination with a custom font. Joiners also serve an important language
purpose in semitic writing systems.

Note that there is a hack where we disregard any character produced
using CTRL or CTRL+SHIFT specifically because of German keyboards. I have chosen to
keep the hack in this patch to limit the change (though I have made an exception
for ZWJ and ZWNJ since both are produced using Ctrl+Shift on Windows), but it
will probably have to be reverted.

[ChangeLog][QtWidgets][Input] Accept characters in Private Use Area, as well as
zero-width joiners and zero-width non-joiners in input in QLineEdit and QTextEdit.

Task-number: QTBUG-42074
Task-number: QTBUG-57003
Change-Id: Ib2c6329e604f3516b8118f027779284adadfc42b
(cherry picked from commit 7896ae052ad2c0c6ae2ebfc64cc2f525185198a8)
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

3 files changed, 113 insertions, 0 deletions

diff --git a/tests/auto/gui/text/qinputcontrol/qinputcontrol.pro b/tests/auto/gui/text/qinputcontrol/qinputcontrol.pro
new file mode 100644
index 0000000000..811c9aab90
--- /dev/null
+++ b/tests/auto/gui/text/qinputcontrol/qinputcontrol.pro
@@ -0,0 +1,7 @@
+CONFIG += testcase
+TARGET = tst_qinputcontrol
+
+QT = core gui gui-private testlib
+
+SOURCES += \
+    tst_qinputcontrol.cpp
diff --git a/tests/auto/gui/text/qinputcontrol/tst_qinputcontrol.cpp b/tests/auto/gui/text/qinputcontrol/tst_qinputcontrol.cpp
new file mode 100644
index 0000000000..318becf6f7
--- /dev/null
+++ b/tests/auto/gui/text/qinputcontrol/tst_qinputcontrol.cpp
@@ -0,0 +1,105 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QtTest>
+
+#include <private/qinputcontrol_p.h>
+#include <QtGui/QKeyEvent>
+
+class tst_QInputControl: public QObject
+{
+    Q_OBJECT
+private slots:
+    void isAcceptableInput_data();
+    void isAcceptableInput();
+    void tabOnlyAcceptableInputForTextEdit();
+};
+
+void tst_QInputControl::isAcceptableInput_data()
+{
+    QTest::addColumn<QString>("text");
+    QTest::addColumn<Qt::KeyboardModifiers>("modifiers");
+    QTest::addColumn<bool>("acceptable");
+
+    QTest::newRow("empty-string") << QString() << Qt::KeyboardModifiers() << false;
+    QTest::newRow("zwnj") << QString(QChar(0x200C)) << Qt::KeyboardModifiers() << true;
+    QTest::newRow("zwnj-with-ctrl") << QString(QChar(0x200C)) << Qt::KeyboardModifiers(Qt::ControlModifier) << true;
+    QTest::newRow("zwnj-with-ctrl-shift") << QString(QChar(0x200C)) << Qt::KeyboardModifiers(Qt::ControlModifier | Qt::ShiftModifier) << true;
+    QTest::newRow("zwj") << QString(QChar(0x200D)) << Qt::KeyboardModifiers() << true;
+    QTest::newRow("zwj-with-ctrl") << QString(QChar(0x200D)) << Qt::KeyboardModifiers(Qt::ControlModifier) << true;
+    QTest::newRow("zwj-with-ctrl-shift") << QString(QChar(0x200D)) << Qt::KeyboardModifiers(Qt::ControlModifier | Qt::ShiftModifier) << true;
+    QTest::newRow("printable-latin") << QString(QLatin1Char('a')) << Qt::KeyboardModifiers() << true;
+    QTest::newRow("printable-latin-with-ctrl") << QString(QLatin1Char('a')) << Qt::KeyboardModifiers(Qt::ControlModifier) << false;
+    QTest::newRow("printable-latin-with-ctrl-shift") << QString(QLatin1Char('a')) << Qt::KeyboardModifiers(Qt::ControlModifier | Qt::ShiftModifier) << false;
+    QTest::newRow("printable-hebrew") << QString(QChar(0x2135)) << Qt::KeyboardModifiers() << true;
+    QTest::newRow("private-use-area") << QString(QChar(0xE832)) << Qt::KeyboardModifiers() << true;
+    QTest::newRow("multiple-printable") << QStringLiteral("foobar") << Qt::KeyboardModifiers() << true;
+}
+
+void tst_QInputControl::isAcceptableInput()
+{
+    QFETCH(QString, text);
+    QFETCH(Qt::KeyboardModifiers, modifiers);
+    QFETCH(bool, acceptable);
+
+    QKeyEvent keyEvent(QKeyEvent::KeyPress, Qt::Key_unknown, modifiers, text);
+
+    {
+        QInputControl inputControl(QInputControl::TextEdit);
+        QCOMPARE(inputControl.isAcceptableInput(&keyEvent), acceptable);
+    }
+
+    {
+        QInputControl inputControl(QInputControl::LineEdit);
+        QCOMPARE(inputControl.isAcceptableInput(&keyEvent), acceptable);
+    }
+}
+
+void tst_QInputControl::tabOnlyAcceptableInputForTextEdit()
+{
+    QKeyEvent keyEvent(QKeyEvent::KeyPress, Qt::Key_unknown, Qt::KeyboardModifiers(), QLatin1String("\t"));
+
+    {
+        QInputControl inputControl(QInputControl::TextEdit);
+        QCOMPARE(inputControl.isAcceptableInput(&keyEvent), true);
+    }
+
+    {
+        QInputControl inputControl(QInputControl::LineEdit);
+        QCOMPARE(inputControl.isAcceptableInput(&keyEvent), false);
+    }
+}
+
+QTEST_MAIN(tst_QInputControl)
+#include "tst_qinputcontrol.moc"
+
diff --git a/tests/auto/gui/text/text.pro b/tests/auto/gui/text/text.pro
index dc67794a98..6f9e4512e8 100644
--- a/tests/auto/gui/text/text.pro
+++ b/tests/auto/gui/text/text.pro
@@ -22,6 +22,7 @@ SUBDIRS=\
    qtextpiecetable \
    qtextscriptengine \
    qtexttable \
+   qinputcontrol
 
 contains(QT_CONFIG, OdfWriter):SUBDIRS += qzip qtextodfwriter