Add borderlayout example

Border layout example ported from C++ to Python

Task-number: PYSIDE-841
Change-Id: I66df4041183ae1eced6fe75d52c21ce381c3d3eb
Reviewed-by: Christian Tismer <tismer@stackless.com>
(cherry picked from commit 14a03a7a55307b41d8664f05216ca9ea1f3c9be7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 298 insertions, 0 deletions

diff --git a/examples/widgets/layouts/borderlayout/borderlayout.py b/examples/widgets/layouts/borderlayout/borderlayout.py
new file mode 100644
index 000000000..74d5524e4
--- /dev/null
+++ b/examples/widgets/layouts/borderlayout/borderlayout.py
@@ -0,0 +1,285 @@
+############################################################################
+##
+## Copyright (C) 2021 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."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+"""PySide6 port of the widgets/layouts/borderlayout example from Qt v5.x"""
+
+from dataclasses import dataclass
+from enum import IntEnum, auto
+
+from PySide6.QtCore import QRect, QSize, Qt
+from PySide6.QtWidgets import (
+    QApplication,
+    QFrame,
+    QLabel,
+    QLayout,
+    QLayoutItem,
+    QTextBrowser,
+    QWidget,
+    QWidgetItem,
+)
+import sys
+
+
+class Position(IntEnum):
+    West = auto()
+    North = auto()
+    South = auto()
+    East = auto()
+    Center = auto()
+
+
+class SizeType(IntEnum):
+    MinimumSize = auto()
+    SizeHint = auto()
+
+
+@dataclass
+class ItemWrapper:
+    item: QLayoutItem
+    position: Position
+
+
+class BorderLayout(QLayout):
+    def __init__(self, parent=None, spacing: int = -1):
+        super().__init__(parent)
+
+        self._list: list[ItemWrapper] = []
+
+        self.setSpacing(spacing)
+
+        if parent is not None:
+            self.setParent(parent)
+
+    def __del__(self):
+        item = self.takeAt(0)
+        while item:
+            item = self.takeAt(0)
+
+    def addItem(self, item: QLayoutItem):
+        self.add(item, Position.West)
+
+    def addWidget(self, widget: QWidget, position: Position):
+        self.add(QWidgetItem(widget), position)
+
+    def expandingDirections(self) -> Qt.Orientations:
+        return Qt.Horizontal | Qt.Vertical
+
+    def hasHeightForWidth(self) -> bool:
+        return False
+
+    def count(self) -> int:
+        return len(self._list)
+
+    def itemAt(self, index: int) -> QLayoutItem:
+        if index < len(self._list):
+            wrapper: ItemWrapper = self._list[index]
+            return wrapper.item
+        return None
+
+    def minimumSize(self) -> QSize:
+        return self.calculate_size(SizeType.MinimumSize)
+
+    def setGeometry(self, rect: QRect):
+        center: ItemWrapper = None
+        east_width = 0
+        west_width = 0
+        north_height = 0
+        south_height = 0
+
+        super().setGeometry(rect)
+
+        for wrapper in self._list:
+            item: QLayoutItem = wrapper.item
+            position: Position = wrapper.position
+
+            if position == Position.North:
+                item.setGeometry(
+                    QRect(
+                        rect.x(), north_height, rect.width(), item.sizeHint().height()
+                    )
+                )
+
+                north_height += item.geometry().height() + self.spacing()
+
+            elif position == Position.South:
+                item.setGeometry(
+                    QRect(
+                        item.geometry().x(),
+                        item.geometry().y(),
+                        rect.width(),
+                        item.sizeHint().height(),
+                    )
+                )
+
+                south_height += item.geometry().height() + self.spacing()
+
+                item.setGeometry(
+                    QRect(
+                        rect.x(),
+                        rect.y() + rect.height() - south_height + self.spacing(),
+                        item.geometry().width(),
+                        item.geometry().height(),
+                    )
+                )
+            elif position == Position.Center:
+                center = wrapper
+
+        center_height = rect.height() - north_height - south_height
+
+        for wrapper in self._list:
+            item: QLayoutItem = wrapper.item
+            position: Position = wrapper.position
+
+            if position == Position.West:
+                item.setGeometry(
+                    QRect(
+                        rect.x() + west_width,
+                        north_height,
+                        item.sizeHint().width(),
+                        center_height,
+                    )
+                )
+
+                west_width += item.geometry().width() + self.spacing()
+
+            elif position == Position.East:
+                item.setGeometry(
+                    QRect(
+                        item.geometry().x(),
+                        item.geometry().y(),
+                        item.sizeHint().width(),
+                        center_height,
+                    )
+                )
+
+                east_width += item.geometry().width() + self.spacing()
+
+                item.setGeometry(
+                    QRect(
+                        rect.x() + rect.width() - east_width + self.spacing(),
+                        north_height,
+                        item.geometry().width(),
+                        item.geometry().height(),
+                    )
+                )
+
+        if center:
+            center.item.setGeometry(
+                QRect(
+                    west_width,
+                    north_height,
+                    rect.width() - east_width - west_width,
+                    center_height,
+                )
+            )
+
+    def sizeHint(self) -> QSize:
+        return self.calculate_size(SizeType.SizeHint)
+
+    def takeAt(self, index: int):
+        if 0 <= index < len(self._list):
+            layout_struct: ItemWrapper = self._list.pop(index)
+            return layout_struct.item
+        return None
+
+    def add(self, item: QLayoutItem, position: Position):
+        self._list.append(ItemWrapper(item, position))
+
+    def calculate_size(self, size_type: SizeType):
+        total_size = QSize()
+
+        for wrapper in self._list:
+            position = wrapper.position
+
+            item_size: QSize
+            if size_type == SizeType.MinimumSize:
+                item_size = wrapper.item.minimumSize()
+            else:
+                item_size = wrapper.item.sizeHint()
+
+            if position in (Position.North, Position.South, Position.Center):
+                total_size.setHeight(total_size.height() + item_size.height())
+
+            if position in (Position.West, Position.East, Position.Center):
+                total_size.setWidth(total_size.width() + item_size.width())
+
+        return total_size
+
+
+class Window(QWidget):
+    def __init__(self):
+        super().__init__()
+        self.central_widget = QTextBrowser()
+        self.central_widget.setPlainText("Central widget")
+
+        border_layout = BorderLayout()
+        border_layout.addWidget(self.central_widget, Position.Center)
+
+        label_north = self.create_label("North")
+        border_layout.addWidget(label_north, Position.North)
+
+        label_west = self.create_label("West")
+        border_layout.addWidget(label_west, Position.West)
+
+        label_east1 = self.create_label("East 1")
+        border_layout.addWidget(label_east1, Position.East)
+
+        label_east2 = self.create_label("East 2")
+        border_layout.addWidget(label_east2, Position.East)
+
+        label_south = self.create_label("South")
+        border_layout.addWidget(label_south, Position.South)
+
+        self.setLayout(border_layout)
+
+        self.setWindowTitle("Border Layout")
+
+    @staticmethod
+    def create_label(text: str):
+        label = QLabel(text)
+        label.setFrameStyle(QFrame.Box | QFrame.Raised)
+        return label
+
+
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+    window = Window()
+    window.show()
+    sys.exit(app.exec())
diff --git a/examples/widgets/layouts/borderlayout/borderlayout.pyproject b/examples/widgets/layouts/borderlayout/borderlayout.pyproject
new file mode 100644
index 000000000..fc0280348
--- /dev/null
+++ b/examples/widgets/layouts/borderlayout/borderlayout.pyproject
@@ -0,0 +1,3 @@
+{
+    "files": ["borderlayout.py"]
+}
diff --git a/examples/widgets/layouts/borderlayout/doc/borderlayout.png b/examples/widgets/layouts/borderlayout/doc/borderlayout.png
new file mode 100644
index 000000000..8599b9d1c
--- /dev/null
+++ b/examples/widgets/layouts/borderlayout/doc/borderlayout.png
diff --git a/examples/widgets/layouts/borderlayout/doc/borderlayout.rst b/examples/widgets/layouts/borderlayout/doc/borderlayout.rst
new file mode 100644
index 000000000..652f84daa
--- /dev/null
+++ b/examples/widgets/layouts/borderlayout/doc/borderlayout.rst
@@ -0,0 +1,10 @@
+Border Layout Example
+=======================
+
+Shows how to arrange child widgets along a border.
+
+Border Layout implements a layout that arranges child widgets to surround the main area.
+
+.. image:: borderlayout.png
+   :width: 473
+   :alt: border layout Screenshot