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: I73f3b7d587a8670de24e902dc52a51f7721dba5a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

4 files changed, 18 insertions, 26 deletions

diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index 9b65dc43d1..a862274a3d 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -1924,19 +1924,15 @@ 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 d4a4534fb5..b9340c0aff 100644
--- a/src/widgets/widgets/qwidgetlinecontrol_p.h
+++ b/src/widgets/widgets/qwidgetlinecontrol_p.h
@@ -64,6 +64,7 @@
 #include "QtCore/qpoint.h"
 #include "QtWidgets/qcompleter.h"
 #include "QtCore/qthread.h"
+#include "QtGui/private/qinputcontrol_p.h"
 
 #include "qplatformdefs.h"
 
@@ -76,13 +77,14 @@
 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_blinkEnabled(false), m_blinkTimer(0), m_deleteAllTimer(0),
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index 47806a194e..f5672bd87a 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -848,21 +848,21 @@ 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);
@@ -1361,14 +1361,7 @@ 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
@@ -1376,7 +1369,7 @@ 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 b45f4fff74..f540a3c9ad 100644
--- a/src/widgets/widgets/qwidgettextcontrol_p.h
+++ b/src/widgets/widgets/qwidgettextcontrol_p.h
@@ -63,6 +63,7 @@
 #include <QtGui/qtextdocumentfragment.h>
 #include <QtGui/qclipboard.h>
 #include <QtCore/qmimedata.h>
+#include <QtGui/private/qinputcontrol_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -75,7 +76,7 @@ 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)