flowlayout.py

#!/usr/bin/env python


#############################################################################
##
# Copyright (C) 2013 Riverbank Computing Limited.
# Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
# All rights reserved.
##
# This file is part of the examples of PyQt.
##
# $QT_BEGIN_LICENSE:BSD$
# You may use this file under the terms of the BSD license as follows:
##
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# 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
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# the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
# the names of its contributors may be used to endorse or promote
# products derived from this software without specific prior written
# permission.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# $QT_END_LICENSE$
##
#############################################################################


from PyQt5.QtCore import QPoint, QRect, QSize, Qt
from PyQt5.QtWidgets import (QApplication, QLayout, QPushButton, QSizePolicy,
                             QWidget)


class Window(QWidget):
    def __init__(self):
        super(Window, self).__init__()

        flowLayout = FlowLayout()
        flowLayout.addWidget(QPushButton("Short"))
        flowLayout.addWidget(QPushButton("Longer"))
        flowLayout.addWidget(QPushButton("Different text"))
        flowLayout.addWidget(QPushButton("More text"))
        flowLayout.addWidget(QPushButton("Even longer button text"))
        self.setLayout(flowLayout)

        self.setWindowTitle("Flow Layout")


class FlowLayout(QLayout):
    def __init__(self, parent=None, margin=0, spacing=-1):
        super(FlowLayout, self).__init__(parent)

        if parent is not None:
            self.setContentsMargins(margin, margin, margin, margin)

        self.setSpacing(spacing)

        self.itemList = []

    def __del__(self):
        item = self.takeAt(0)
        while item:
            item = self.takeAt(0)

    def addItem(self, item):
        self.itemList.append(item)

    def count(self):
        return len(self.itemList)

    def itemAt(self, index):
        if index >= 0 and index < len(self.itemList):
            return self.itemList[index]

        return None

    def takeAt(self, index):
        if index >= 0 and index < len(self.itemList):
            return self.itemList.pop(index)

        return None

    def expandingDirections(self):
        return Qt.Orientations(Qt.Orientation(0))

    def hasHeightForWidth(self):
        return True

    def heightForWidth(self, width):
        height = self.doLayout(QRect(0, 0, width, 0), True)
        return height

    def setGeometry(self, rect):
        super(FlowLayout, self).setGeometry(rect)
        self.doLayout(rect, False)

    def sizeHint(self):
        return self.minimumSize()

    def minimumSize(self):
        size = QSize()

        for item in self.itemList:
            size = size.expandedTo(item.minimumSize())

        margin, _, _, _ = self.getContentsMargins()

        size += QSize(2 * margin, 2 * margin)
        return size

    def doLayout(self, rect, testOnly):
        x = rect.x()
        y = rect.y()
        lineHeight = 0

        for item in self.itemList:
            wid = item.widget()
            spaceX = self.spacing() + wid.style().layoutSpacing(QSizePolicy.PushButton,
                                                                QSizePolicy.PushButton, Qt.Horizontal)
            spaceY = self.spacing() + wid.style().layoutSpacing(QSizePolicy.PushButton,
                                                                QSizePolicy.PushButton, Qt.Vertical)
            nextX = x + item.sizeHint().width() + spaceX
            if nextX - spaceX > rect.right() and lineHeight > 0:
                x = rect.x()
                y = y + lineHeight + spaceY
                nextX = x + item.sizeHint().width() + spaceX
                lineHeight = 0

            if not testOnly:
                item.setGeometry(QRect(QPoint(x, y), item.sizeHint()))

            x = nextX
            lineHeight = max(lineHeight, item.sizeHint().height())

        return y + lineHeight - rect.y()


if __name__ == '__main__':

    import sys

    app = QApplication(sys.argv)
    mainWin = Window()
    mainWin.show()
    sys.exit(app.exec_())