Add QTextMarkdownWriter, QTextEdit::markdown property etc.

A QTextDocument can now be written out in Markdown format.

- Add the QTextMarkdownWriter as a private class for now
- Add QTextDocument::toMarkdown()
- QTextDocumentWriter uses QTextMarkdownWriter if setFormat("markdown")
  is called or if the file suffix is .md or .mkd
- Add QTextEdit::toMarkdown() and the markdown property

[ChangeLog][QtGui][Text] Markdown (CommonMark or GitHub dialect) is now
a supported format for reading into and writing from QTextDocument.

Change-Id: I663a77017fac7ae1b3f9a400f5cd357bb40750af
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 78 insertions, 0 deletions

diff --git a/src/gui/text/qtextmarkdownwriter_p.h b/src/gui/text/qtextmarkdownwriter_p.h
new file mode 100644
index 0000000000..9845355259
--- /dev/null
+++ b/src/gui/text/qtextmarkdownwriter_p.h
@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QTEXTMARKDOWNWRITER_P_H
+#define QTEXTMARKDOWNWRITER_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 <QtGui/private/qtguiglobal_p.h>
+#include <QtCore/QTextStream>
+
+#include "qtextdocument_p.h"
+#include "qtextdocumentwriter.h"
+
+QT_BEGIN_NAMESPACE
+
+class Q_GUI_EXPORT QTextMarkdownWriter
+{
+public:
+    QTextMarkdownWriter(QTextStream &stream, QTextDocument::MarkdownFeatures features);
+    bool writeAll(const QTextDocument &document);
+
+    int writeBlock(const QTextBlock &block, bool table, bool ignoreFormat);
+    void writeFrame(const QTextFrame *frame);
+
+private:
+    QTextStream &m_stream;
+    QTextDocument::MarkdownFeatures m_features;
+};
+
+QT_END_NAMESPACE
+
+#endif // QTEXTMARKDOWNWRITER_P_H