# https://doc.qt.io/qtforpython-6/examples/example_widgets_layouts_flowlayout.html
# Copyright (C) 2013 Riverbank Computing Limited.
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
"""PySide6 port of the widgets/layouts/flowlayout example from Qt v6.x"""
from __future__ import annotations
import typing
from edifice.qt import QT_VERSION
if QT_VERSION == "PyQt6" and not typing.TYPE_CHECKING:
from PyQt6.QtCore import QPoint, QRect, QSize, Qt
from PyQt6.QtWidgets import QLayout, QLayoutItem, QSizePolicy, QWidget
else:
from PySide6.QtCore import QPoint, QRect, QSize, Qt
from PySide6.QtWidgets import QLayout, QLayoutItem, QSizePolicy, QWidget
from edifice.base_components.base_components import QtWidgetElement, _LinearView
from edifice.engine import CommandType, Element, _get_widget_children, _WidgetTree
if typing.TYPE_CHECKING:
from edifice.engine import PropsDiff
class FlowLayout(QLayout):
def __init__(self, parent=None):
super().__init__(parent)
self._item_list: list[QLayoutItem] = []
def __del__(self):
item = self.takeAt(0)
while item:
item = self.takeAt(0)
def addItem(self, arg__1: QLayoutItem) -> None:
self._item_list.append(arg__1)
def count(self) -> int:
return len(self._item_list)
def itemAt(self, index) -> QLayoutItem | None:
if 0 <= index < len(self._item_list):
return self._item_list[index]
return None
# Contradiction between the docs and the type.
# https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QLayout.html#PySide6.QtWidgets.QLayout.takeAt
def takeAt(self, index: int) -> QLayoutItem | None: # type: ignore # noqa: PGH003
if 0 <= index < len(self._item_list):
return self._item_list.pop(index)
return None
# We need insertWidget like the one in QBoxLayout to support Edifice.
# https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QBoxLayout.html#PySide6.QtWidgets.QBoxLayout.insertWidget
#
# But the QLayout API gives us only addWidget and removeWidget.
# https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QLayout.html
#
# So we have to write insertWidget in terms of addWidget and removeWidget.
#
# This is O(N) for inserting at the beginning of a FlowLayout.
def insertWidget(self, index: int, w: QWidget) -> None:
stack = []
while len(self._item_list) > index:
w_ = self._item_list[-1].widget()
self.removeWidget(w_)
stack.append(w_)
self.addWidget(w)
while len(stack) > 0:
self.addWidget(stack.pop())
def expandingDirections(self):
return Qt.Orientation(0)
def hasHeightForWidth(self):
return True
def heightForWidth(self, arg__1):
return self._do_layout(QRect(0, 0, arg__1, 0), True)
def setGeometry(self, arg__1: QRect):
super().setGeometry(arg__1)
self._do_layout(arg__1, 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.ControlType.PushButton,
QSizePolicy.ControlType.PushButton,
Qt.Orientation.Horizontal,
)
layout_spacing_y = style.layoutSpacing(
QSizePolicy.ControlType.PushButton,
QSizePolicy.ControlType.PushButton,
Qt.Orientation.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()
[docs]
class FlowView(_LinearView[QWidget]):
"""
Flow-style layout.
.. highlights::
- Underlying Qt Widget `QWidget <https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QWidget.html>`_
- Underlying Qt Layout `QLayout <https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QLayout.html>`_
Displays its children horizonally left-to-right and wraps into multiple rows.
The height of each row is determined by the tallest child in that row.
This component has similar behavior to an `HTML CSS
wrap flex container <https://developer.mozilla.org/en-US/docs/Web/CSS/flex-wrap>`_.
.. note::
The :class:`FlowView` element is implemented in Python because Qt does not provide
any native :code:`QLayout` which behaves this way. Currently the :class:`FlowView`
has *O(N)* time complexity for inserting a child at the beginning
of *N* children because of technical limitations of the Qt API.
.. rubric:: Props
All **props** for :class:`QtWidgetElement`.
"""
[docs]
def __init__(self, **kwargs):
super().__init__(**kwargs)
def _delete_child(self, i, old_child: QtWidgetElement): # noqa: ARG002
assert self.underlying_layout is not None
child_node = self.underlying_layout.takeAt(i)
assert child_node is not None
child_node.widget().deleteLater()
def _soft_delete_child(self, i, old_child: QtWidgetElement): # noqa: ARG002
assert self.underlying_layout is not None
child_node = self.underlying_layout.takeAt(i)
assert child_node is not None
def _add_child(self, i, child_component: QWidget):
self.underlying_layout.insertWidget(i, child_component)
def _initialize(self):
self.underlying = QWidget()
self.underlying_layout = FlowLayout()
self.underlying.setObjectName(str(id(self)))
self.underlying.setLayout(self.underlying_layout)
self.underlying_layout.setContentsMargins(0, 0, 0, 0)
self.underlying_layout.setSpacing(0)
def _qt_update_commands(
self,
widget_trees: dict[Element, _WidgetTree],
diff_props: PropsDiff,
):
if self.underlying is None:
self._initialize()
assert self.underlying is not None
children = _get_widget_children(widget_trees, self)
commands: list[CommandType] = []
child_commands = self._recompute_children(children)
commands.extend(child_commands)
if len(child_commands) > 0:
# If we have children commands then we update the underlying layout.
# This is to mitigate a bug in which the FlowLayout does not update
# sometimes when children are re-ordered.
#
# https://doc.qt.io/qtforpython-6/PySide6/QtWidgets/QLayout.html#PySide6.QtWidgets.QLayout.update
# https://doc.qt.io/qt-6/qlayout.html#update
#
# “You should generally not need to call this because it is automatically called at
# the most appropriate times.”
commands.append(CommandType(self.underlying_layout.update))
commands.extend(
super()._qt_update_commands_super(widget_trees, diff_props, self.underlying, self.underlying_layout),
)
return commands
