Add codeeditor example

Based on Qt's Code Editor example

Change-Id: I17ba0dfbafcda5a599cd2ef051e842cdd4b6e305
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

2 files changed, 193 insertions, 0 deletions

diff --git a/examples/widgets/codeeditor/codeeditor.py b/examples/widgets/codeeditor/codeeditor.py
new file mode 100644
index 000000000..331069f4a
--- /dev/null
+++ b/examples/widgets/codeeditor/codeeditor.py
@@ -0,0 +1,141 @@
+#############################################################################
+##
+## Copyright (C) 2019 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Qt for Python examples of the Qt Toolkit.
+##
+## $QT_BEGIN_LICENSE:BSD$
+## You may use this file under the terms of the BSD license as follows:
+##
+## "Redistribution and use in source and binary forms, with or without
+## modification, are permitted provided that the following conditions are
+## met:
+##   * Redistributions of source code must retain the above copyright
+##     notice, this list of conditions and the following disclaimer.
+##   * Redistributions in binary form must reproduce the above copyright
+##     notice, this list of conditions and the following disclaimer in
+##     the documentation and/or other materials provided with the
+##     distribution.
+##   * Neither the name of The Qt Company Ltd nor the names of its
+##     contributors may be used to endorse or promote products derived
+##     from this software without specific prior written permission.
+##
+##
+## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+from PySide2.QtCore import Slot, Qt, QRect, QSize
+from PySide2.QtGui import QColor, QPainter, QTextFormat
+from PySide2.QtWidgets import QPlainTextEdit, QWidget, QTextEdit
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        QWidget.__init__(self, editor)
+        self.codeEditor = editor
+
+    def sizeHint(self):
+        return QSize(self.codeEditor.line_number_area_width(), 0)
+
+    def paintEvent(self, event):
+        self.codeEditor.lineNumberAreaPaintEvent(event)
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        QPlainTextEdit.__init__(self)
+        self.line_number_area = LineNumberArea(self)
+
+        self.blockCountChanged[int].connect(self.update_line_number_area_width)
+        self.updateRequest[QRect, int].connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_area_width(0)
+        self.highlight_current_line()
+
+    def line_number_area_width(self):
+        digits = 1
+        max_num = max(1, self.blockCount())
+        while max_num >= 10:
+            max_num *= 0.1
+            digits += 1
+
+        space = 3 + self.fontMetrics().width('9') * digits
+        return space
+
+    def resizeEvent(self, e):
+        super().resizeEvent(e)
+        cr = self.contentsRect()
+        width = self.line_number_area_width()
+        rect = QRect(cr.left(), cr.top(), width, cr.height())
+        self.line_number_area.setGeometry(rect)
+
+    def lineNumberAreaPaintEvent(self, event):
+        painter = QPainter(self.line_number_area)
+        painter.fillRect(event.rect(), Qt.lightGray)
+        block = self.firstVisibleBlock()
+        block_number = block.blockNumber()
+        offset = self.contentOffset()
+        top = self.blockBoundingGeometry(block).translated(offset).top()
+        bottom = top + self.blockBoundingRect(block).height()
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                number = str(block_number + 1)
+                painter.setPen(Qt.black)
+                width = self.line_number_area.width()
+                height = self.fontMetrics().height()
+                painter.drawText(0, top, width, height, Qt.AlignRight, number)
+
+            block = block.next()
+            top = bottom
+            bottom = top + self.blockBoundingRect(block).height()
+            block_number += 1
+
+    @Slot()
+    def update_line_number_area_width(self, newBlockCount):
+        self.setViewportMargins(self.line_number_area_width(), 0, 0, 0)
+
+    @Slot()
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_number_area.scroll(0, dy)
+        else:
+            width = self.line_number_area.width()
+            self.line_number_area.update(0, rect.y(), width, rect.height())
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_area_width(0)
+
+    @Slot()
+    def highlight_current_line(self):
+        extra_selections = []
+
+        if not self.isReadOnly():
+            selection = QTextEdit.ExtraSelection()
+
+            line_color = QColor(Qt.yellow).lighter(160)
+            selection.format.setBackground(line_color)
+
+            selection.format.setProperty(QTextFormat.FullWidthSelection, True)
+
+            selection.cursor = self.textCursor()
+            selection.cursor.clearSelection()
+
+            extra_selections.append(selection)
+
+        self.setExtraSelections(extra_selections)
diff --git a/examples/widgets/codeeditor/main.py b/examples/widgets/codeeditor/main.py
new file mode 100644
index 000000000..14c2e0826
--- /dev/null
+++ b/examples/widgets/codeeditor/main.py
@@ -0,0 +1,52 @@
+#############################################################################
+##
+## Copyright (C) 2019 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Qt for Python examples of the Qt Toolkit.
+##
+## $QT_BEGIN_LICENSE:BSD$
+## You may use this file under the terms of the BSD license as follows:
+##
+## "Redistribution and use in source and binary forms, with or without
+## modification, are permitted provided that the following conditions are
+## met:
+##   * Redistributions of source code must retain the above copyright
+##     notice, this list of conditions and the following disclaimer.
+##   * Redistributions in binary form must reproduce the above copyright
+##     notice, this list of conditions and the following disclaimer in
+##     the documentation and/or other materials provided with the
+##     distribution.
+##   * Neither the name of The Qt Company Ltd nor the names of its
+##     contributors may be used to endorse or promote products derived
+##     from this software without specific prior written permission.
+##
+##
+## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+import sys
+from PySide2.QtWidgets import QApplication
+from codeeditor import CodeEditor
+
+"""PySide2 port of the widgets/codeeditor example from Qt5"""
+
+if __name__ == "__main__":
+    app = QApplication([])
+    editor = CodeEditor()
+    editor.setWindowTitle("Code Editor Example")
+    editor.show()
+    sys.exit(app.exec_())