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>

10 files changed, 293 insertions, 28 deletions

diff --git a/src/gui/text/qinputcontrol.cpp b/src/gui/text/qinputcontrol.cpp
new file mode 100644
index 0000000000..c2c198866a
--- /dev/null
+++ b/src/gui/text/qinputcontrol.cpp
@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module 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 "qinputcontrol_p.h"
+#include <QtGui/qevent.h>
+
+QT_BEGIN_NAMESPACE
+
+QInputControl::QInputControl(Type type, QObject *parent)
+    : QObject(parent)
+    , m_type(type)
+{
+}
+
+QInputControl::QInputControl(Type type, QObjectPrivate &dd, QObject *parent)
+    : QObject(dd, parent)
+    , m_type(type)
+{
+}
+
+bool QInputControl::isAcceptableInput(const QKeyEvent *event) const
+{
+    const QString text = event->text();
+    if (text.isEmpty())
+        return false;
+
+    const QChar c = text.at(0);
+
+    // ZWNJ and ZWJ. This needs to go before the next test, since CTRL+SHIFT is
+    // used to input it on Windows.
+    if (c == QChar(0x200C) || c == QChar(0x200D))
+        return true;
+
+    // QTBUG-35734: ignore Ctrl/Ctrl+Shift; accept only AltGr (Alt+Ctrl) on German keyboards
+    if (event->modifiers() == Qt::ControlModifier
+            || event->modifiers() == (Qt::ShiftModifier | Qt::ControlModifier)) {
+        return false;
+    }
+
+    if (c.isPrint())
+        return true;
+
+    if (c.category() == QChar::Other_PrivateUse)
+        return true;
+
+    if (m_type == TextEdit && c == QLatin1Char('\t'))
+        return true;
+
+    return false;
+}
+
+QT_END_NAMESPACE
diff --git a/src/gui/text/qinputcontrol_p.h b/src/gui/text/qinputcontrol_p.h
new file mode 100644
index 0000000000..c4f53d987f
--- /dev/null
+++ b/src/gui/text/qinputcontrol_p.h
@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QINPUTCONTROL_P_H
+#define QINPUTCONTROL_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. It exists purely as an
+// implementation detail. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qobject.h>
+#include <qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+class QKeyEvent;
+class Q_GUI_EXPORT QInputControl : public QObject
+{
+    Q_OBJECT
+public:
+    enum Type {
+        LineEdit,
+        TextEdit
+    };
+
+    explicit QInputControl(Type type, QObject *parent = Q_NULLPTR);
+
+    bool isAcceptableInput(const QKeyEvent *event) const;
+
+protected:
+    explicit QInputControl(Type type, QObjectPrivate &dd, QObject *parent = Q_NULLPTR);
+
+private:
+    const Type m_type;
+};
+
+QT_END_NAMESPACE
+
+#endif // QINPUTCONTROL_P_H
diff --git a/src/gui/text/text.pri b/src/gui/text/text.pri
index be60ba72cc..3848b20dec 100644
--- a/src/gui/text/text.pri
+++ b/src/gui/text/text.pri
@@ -43,7 +43,8 @@ HEADERS += \
     text/qrawfont_p.h \
     text/qglyphrun.h \
     text/qglyphrun_p.h \
-    text/qdistancefield_p.h
+    text/qdistancefield_p.h \
+    text/qinputcontrol_p.h
 
 SOURCES += \
     text/qfont.cpp \
@@ -76,7 +77,8 @@ SOURCES += \
     text/qstatictext.cpp \
     text/qrawfont.cpp \
     text/qglyphrun.cpp \
-    text/qdistancefield.cpp
+    text/qdistancefield.cpp \
+    text/qinputcontrol.cpp
 
 SOURCES += \
     text/qfontengine_qpf2.cpp \
diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index daf9f00c46..866002370a 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -1881,19 +1881,15 @@ void QWidgetLineControl::processKeyEvent(QKeyEvent* event)
         unknown = false;
     }
 
-    // QTBUG-35734: ignore Ctrl/Ctrl+Shift; accept only AltGr (Alt+Ctrl) on German keyboards
-    if (unknown && !isReadOnly()
-        && event->modifiers() != Qt::ControlModifier
-        && event->modifiers() != (Qt::ControlModifier | Qt::ShiftModifier)) {
-        QString t = event->text();
-        if (!t.isEmpty() && t.at(0).isPrint()) {
-            insert(t);
+    if (unknown
+        && !isReadOnly()
+        && isAcceptableInput(event)) {
+        insert(event->text());
 #ifndef QT_NO_COMPLETER
-            complete(event->key());
+        complete(event->key());
 #endif
-            event->accept();
-            return;
-        }
+        event->accept();
+        return;
     }
 
     if (unknown)
diff --git a/src/widgets/widgets/qwidgetlinecontrol_p.h b/src/widgets/widgets/qwidgetlinecontrol_p.h
index 3d8df9e3ff..a17cd98ced 100644
--- a/src/widgets/widgets/qwidgetlinecontrol_p.h
+++ b/src/widgets/widgets/qwidgetlinecontrol_p.h
@@ -58,6 +58,7 @@
 #include "QtCore/qpoint.h"
 #include "QtWidgets/qcompleter.h"
 #include "QtCore/qthread.h"
+#include "QtGui/private/qinputcontrol_p.h"
 
 #include "qplatformdefs.h"
 
@@ -70,13 +71,14 @@
 QT_BEGIN_NAMESPACE
 
 
-class Q_WIDGETS_EXPORT QWidgetLineControl : public QObject
+class Q_WIDGETS_EXPORT QWidgetLineControl : public QInputControl
 {
     Q_OBJECT
 
 public:
     QWidgetLineControl(const QString &txt = QString())
-        : m_cursor(0), m_preeditCursor(0), m_cursorWidth(0), m_layoutDirection(Qt::LayoutDirectionAuto),
+        : QInputControl(LineEdit)
+        , m_cursor(0), m_preeditCursor(0), m_cursorWidth(0), m_layoutDirection(Qt::LayoutDirectionAuto),
         m_hideCursor(false), m_separator(0), m_readOnly(0),
         m_dragEnabled(0), m_echoMode(0), m_textDirty(0), m_selDirty(0),
         m_validInput(1), m_blinkStatus(0), m_blinkPeriod(0), m_blinkTimer(0), m_deleteAllTimer(0),
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index 4199ae537d..b8effff206 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -829,21 +829,21 @@ void QWidgetTextControl::redo()
 }
 
 QWidgetTextControl::QWidgetTextControl(QObject *parent)
-    : QObject(*new QWidgetTextControlPrivate, parent)
+    : QInputControl(QInputControl::TextEdit, *new QWidgetTextControlPrivate, parent)
 {
     Q_D(QWidgetTextControl);
     d->init();
 }
 
 QWidgetTextControl::QWidgetTextControl(const QString &text, QObject *parent)
-    : QObject(*new QWidgetTextControlPrivate, parent)
+    : QInputControl(QInputControl::TextEdit, *new QWidgetTextControlPrivate, parent)
 {
     Q_D(QWidgetTextControl);
     d->init(Qt::RichText, text);
 }
 
 QWidgetTextControl::QWidgetTextControl(QTextDocument *doc, QObject *parent)
-    : QObject(*new QWidgetTextControlPrivate, parent)
+    : QInputControl(QInputControl::TextEdit, *new QWidgetTextControlPrivate, parent)
 {
     Q_D(QWidgetTextControl);
     d->init(Qt::RichText, QString(), doc);
@@ -1342,14 +1342,7 @@ void QWidgetTextControlPrivate::keyPressEvent(QKeyEvent *e)
 
 process:
     {
-        // QTBUG-35734: ignore Ctrl/Ctrl+Shift; accept only AltGr (Alt+Ctrl) on German keyboards
-        if (e->modifiers() == Qt::ControlModifier
-            || e->modifiers() == (Qt::ShiftModifier | Qt::ControlModifier)) {
-            e->ignore();
-            return;
-        }
-        QString text = e->text();
-        if (!text.isEmpty() && (text.at(0).isPrint() || text.at(0) == QLatin1Char('\t'))) {
+        if (q->isAcceptableInput(e)) {
             if (overwriteMode
                 // no need to call deleteChar() if we have a selection, insertText
                 // does it already
@@ -1357,7 +1350,7 @@ process:
                 && !cursor.atBlockEnd())
                 cursor.deleteChar();
 
-            cursor.insertText(text);
+            cursor.insertText(e->text());
             selectionChanged();
         } else {
             e->ignore();
diff --git a/src/widgets/widgets/qwidgettextcontrol_p.h b/src/widgets/widgets/qwidgettextcontrol_p.h
index cd5abf4f5d..5bdd3309a7 100644
--- a/src/widgets/widgets/qwidgettextcontrol_p.h
+++ b/src/widgets/widgets/qwidgettextcontrol_p.h
@@ -56,6 +56,7 @@
 #include <QtGui/qtextdocumentfragment.h>
 #include <QtGui/qclipboard.h>
 #include <QtCore/qmimedata.h>
+#include <QtGui/private/qinputcontrol_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -68,7 +69,7 @@ class QAbstractScrollArea;
 class QEvent;
 class QTimerEvent;
 
-class Q_WIDGETS_EXPORT QWidgetTextControl : public QObject
+class Q_WIDGETS_EXPORT QWidgetTextControl : public QInputControl
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QWidgetTextControl)
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