New multi line editor

Supports zooming in and out with ctrl+scroll.

It is a bit hacky, since I use sed in make to make it work, but
whatever.

Makefile

@@ -5,6 +5,8 @@ pyqt:
 	pyuic5 relational_gui/maingui.ui > relational_gui/maingui.py
 	pyuic5 relational_gui/rel_edit.ui > relational_gui/rel_edit.py
 	pyrcc5 relational_gui/resources.qrc > relational_gui/resources.py
+	sed -i 's/QtWidgets.QPlainTextEdit/editor.Editor/g' relational_gui/maingui.py
+	echo 'from . import editor' >> relational_gui/maingui.py
 
 dist: clean
 	rm -rf /tmp/relational/

relational_gui/editor.py

@@ -0,0 +1,43 @@
+# Relational
+# Copyright (C) 2016  Salvo "LtWorf" Tomaselli
+#
+# Relational is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# author Salvo "LtWorf" Tomaselli <tiposchi@tiscali.it>
+#
+# This module provides a classes to represent relations and to perform
+# relational operations on them.
+
+from PyQt5.QtWidgets import QPlainTextEdit
+from PyQt5.QtCore import Qt
+
+
+class Editor(QPlainTextEdit):
+
+    def __init__(self, *args, **kwargs):
+        super(Editor, self).__init__(*args, **kwargs)
+
+    def wheelEvent(self, event):
+        if event.modifiers() & Qt.ControlModifier:
+            event.accept()
+            self.zoom(1 if event.angleDelta().y()>0 else -1)
+        else:
+            super(Editor, self).wheelEvent(event)
+
+    def zoom(self, incr):
+        font = self.font()
+        point_size = font.pointSize()
+        point_size += incr
+        font.setPointSize(point_size)
+        self.setFont(font)