Flow Layout Example¶
Flow Layout implements a layout that handles different window sizes in a Qt Widgets application. The widget placement changes depending on the width of the application window.
# Copyright (C) 2013 Riverbank Computing Limited.
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
"""PySide6 port of the widgets/layouts/flowlayout example from Qt v6.x"""
import sys
from PySide6.QtCore import Qt, QMargins, QPoint, QRect, QSize
from PySide6.QtWidgets import QApplication, QLayout, QPushButton, QSizePolicy, QWidget
class Window(QWidget):
def __init__(self):
super().__init__()
flow_layout = FlowLayout(self)
flow_layout.addWidget(QPushButton("Short"))
flow_layout.addWidget(QPushButton("Longer"))
flow_layout.addWidget(QPushButton("Different text"))
flow_layout.addWidget(QPushButton("More text"))
flow_layout.addWidget(QPushButton("Even longer button text"))
self.setWindowTitle("Flow Layout")
class FlowLayout(QLayout):
def __init__(self, parent=None):
super().__init__(parent)
if parent is not None:
self.setContentsMargins(QMargins(0, 0, 0, 0))
self._item_list = []
def __del__(self):
item = self.takeAt(0)
while item:
item = self.takeAt(0)
def addItem(self, item):
self._item_list.append(item)
def count(self):
return len(self._item_list)
def itemAt(self, index):
if 0 <= index < len(self._item_list):
return self._item_list[index]
return None
def takeAt(self, index):
if 0 <= index < len(self._item_list):
return self._item_list.pop(index)
return None
def expandingDirections(self):
return Qt.Orientation(0)
def hasHeightForWidth(self):
return True
def heightForWidth(self, width):
height = self._do_layout(QRect(0, 0, width, 0), True)
return height
def setGeometry(self, rect):
super(FlowLayout, self).setGeometry(rect)
self._do_layout(rect, False)
def sizeHint(self):
return self.minimumSize()
def minimumSize(self):
size = QSize()
for item in self._item_list:
size = size.expandedTo(item.minimumSize())
size += QSize(2 * self.contentsMargins().top(), 2 * self.contentsMargins().top())
return size
def _do_layout(self, rect, test_only):
x = rect.x()
y = rect.y()
line_height = 0
spacing = self.spacing()
for item in self._item_list:
style = item.widget().style()
layout_spacing_x = style.layoutSpacing(
QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Orientation.Horizontal
)
layout_spacing_y = style.layoutSpacing(
QSizePolicy.PushButton, QSizePolicy.PushButton, Qt.Vertical
)
space_x = spacing + layout_spacing_x
space_y = spacing + layout_spacing_y
next_x = x + item.sizeHint().width() + space_x
if next_x - space_x > rect.right() and line_height > 0:
x = rect.x()
y = y + line_height + space_y
next_x = x + item.sizeHint().width() + space_x
line_height = 0
if not test_only:
item.setGeometry(QRect(QPoint(x, y), item.sizeHint()))
x = next_x
line_height = max(line_height, item.sizeHint().height())
return y + line_height - rect.y()
if __name__ == "__main__":
app = QApplication(sys.argv)
main_win = Window()
main_win.show()
sys.exit(app.exec())