Article Outline
Python pyqt (gui) example 'mdi'
Modules used in program:
import mdi_rc
mdi
Python pyqt example: mdi
#!/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:
##
## "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 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
## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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## $QT_END_LICENSE$
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#############################################################################
from PyQt5.QtCore import (QFile, QFileInfo, QPoint, QSettings, QSignalMapper,
QSize, QTextStream, Qt)
from PyQt5.QtGui import QIcon, QKeySequence
from PyQt5.QtWidgets import (QAction, QApplication, QFileDialog, QMainWindow,
QMdiArea, QMessageBox, QTextEdit, QWidget)
import mdi_rc
class MdiChild(QTextEdit):
sequenceNumber = 1
def __init__(self):
super(MdiChild, self).__init__()
self.setAttribute(Qt.WA_DeleteOnClose)
self.isUntitled = True
def newFile(self):
self.isUntitled = True
self.curFile = "document%d.txt" % MdiChild.sequenceNumber
MdiChild.sequenceNumber += 1
self.setWindowTitle(self.curFile + '[*]')
self.document().contentsChanged.connect(self.documentWasModified)
def loadFile(self, fileName):
file = QFile(fileName)
if not file.open(QFile.ReadOnly | QFile.Text):
QMessageBox.warning(self, "MDI",
"Cannot read file %s:\n%s." % (fileName, file.errorString()))
return False
instr = QTextStream(file)
QApplication.setOverrideCursor(Qt.WaitCursor)
self.setPlainText(instr.readAll())
QApplication.restoreOverrideCursor()
self.setCurrentFile(fileName)
self.document().contentsChanged.connect(self.documentWasModified)
return True
def save(self):
if self.isUntitled:
return self.saveAs()
else:
return self.saveFile(self.curFile)
def saveAs(self):
fileName, _ = QFileDialog.getSaveFileName(self, "Save As", self.curFile)
if not fileName:
return False
return self.saveFile(fileName)
def saveFile(self, fileName):
file = QFile(fileName)
if not file.open(QFile.WriteOnly | QFile.Text):
QMessageBox.warning(self, "MDI",
"Cannot write file %s:\n%s." % (fileName, file.errorString()))
return False
outstr = QTextStream(file)
QApplication.setOverrideCursor(Qt.WaitCursor)
outstr << self.toPlainText()
QApplication.restoreOverrideCursor()
self.setCurrentFile(fileName)
return True
def userFriendlyCurrentFile(self):
return self.strippedName(self.curFile)
def currentFile(self):
return self.curFile
def closeEvent(self, event):
if self.maybeSave():
event.accept()
else:
event.ignore()
def documentWasModified(self):
self.setWindowModified(self.document().isModified())
def maybeSave(self):
if self.document().isModified():
ret = QMessageBox.warning(self, "MDI",
"'%s' has been modified.\nDo you want to save your "
"changes?" % self.userFriendlyCurrentFile(),
QMessageBox.Save | QMessageBox.Discard | QMessageBox.Cancel)
if ret == QMessageBox.Save:
return self.save()
if ret == QMessageBox.Cancel:
return False
return True
def setCurrentFile(self, fileName):
self.curFile = QFileInfo(fileName).canonicalFilePath()
self.isUntitled = False
self.document().setModified(False)
self.setWindowModified(False)
self.setWindowTitle(self.userFriendlyCurrentFile() + "[*]")
def strippedName(self, fullFileName):
return QFileInfo(fullFileName).fileName()
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.mdiArea = QMdiArea()
self.mdiArea.setHorizontalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.mdiArea.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.setCentralWidget(self.mdiArea)
self.mdiArea.subWindowActivated.connect(self.updateMenus)
self.windowMapper = QSignalMapper(self)
self.windowMapper.mapped[QWidget].connect(self.setActiveSubWindow)
self.createActions()
self.createMenus()
self.createToolBars()
self.createStatusBar()
self.updateMenus()
self.readSettings()
self.setWindowTitle("MDI")
def closeEvent(self, event):
self.mdiArea.closeAllSubWindows()
if self.mdiArea.currentSubWindow():
event.ignore()
else:
self.writeSettings()
event.accept()
def newFile(self):
child = self.createMdiChild()
child.newFile()
child.show()
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self)
if fileName:
existing = self.findMdiChild(fileName)
if existing:
self.mdiArea.setActiveSubWindow(existing)
return
child = self.createMdiChild()
if child.loadFile(fileName):
self.statusBar().showMessage("File loaded", 2000)
child.show()
else:
child.close()
def save(self):
if self.activeMdiChild() and self.activeMdiChild().save():
self.statusBar().showMessage("File saved", 2000)
def saveAs(self):
if self.activeMdiChild() and self.activeMdiChild().saveAs():
self.statusBar().showMessage("File saved", 2000)
def cut(self):
if self.activeMdiChild():
self.activeMdiChild().cut()
def copy(self):
if self.activeMdiChild():
self.activeMdiChild().copy()
def paste(self):
if self.activeMdiChild():
self.activeMdiChild().paste()
def about(self):
QMessageBox.about(self, "About MDI",
"The <b>MDI</b> example demonstrates how to write multiple "
"document interface applications using Qt.")
def updateMenus(self):
hasMdiChild = (self.activeMdiChild() is not None)
self.saveAct.setEnabled(hasMdiChild)
self.saveAsAct.setEnabled(hasMdiChild)
self.pasteAct.setEnabled(hasMdiChild)
self.closeAct.setEnabled(hasMdiChild)
self.closeAllAct.setEnabled(hasMdiChild)
self.tileAct.setEnabled(hasMdiChild)
self.cascadeAct.setEnabled(hasMdiChild)
self.nextAct.setEnabled(hasMdiChild)
self.previousAct.setEnabled(hasMdiChild)
self.separatorAct.setVisible(hasMdiChild)
hasSelection = (self.activeMdiChild() is not None and
self.activeMdiChild().textCursor().hasSelection())
self.cutAct.setEnabled(hasSelection)
self.copyAct.setEnabled(hasSelection)
def updateWindowMenu(self):
self.windowMenu.clear()
self.windowMenu.addAction(self.closeAct)
self.windowMenu.addAction(self.closeAllAct)
self.windowMenu.addSeparator()
self.windowMenu.addAction(self.tileAct)
self.windowMenu.addAction(self.cascadeAct)
self.windowMenu.addSeparator()
self.windowMenu.addAction(self.nextAct)
self.windowMenu.addAction(self.previousAct)
self.windowMenu.addAction(self.separatorAct)
windows = self.mdiArea.subWindowList()
self.separatorAct.setVisible(len(windows) != 0)
for i, window in enumerate(windows):
child = window.widget()
text = "%d %s" % (i + 1, child.userFriendlyCurrentFile())
if i < 9:
text = '&' + text
action = self.windowMenu.addAction(text)
action.setCheckable(True)
action.setChecked(child is self.activeMdiChild())
action.triggered.connect(self.windowMapper.map)
self.windowMapper.setMapping(action, window)
def createMdiChild(self):
child = MdiChild()
self.mdiArea.addSubWindow(child)
child.copyAvailable.connect(self.cutAct.setEnabled)
child.copyAvailable.connect(self.copyAct.setEnabled)
return child
def createActions(self):
self.newAct = QAction(QIcon(':/images/new.png'), "&New", self,
shortcut=QKeySequence.New, statusTip="Create a new file",
triggered=self.newFile)
self.openAct = QAction(QIcon(':/images/open.png'), "&Open...", self,
shortcut=QKeySequence.Open, statusTip="Open an existing file",
triggered=self.open)
self.saveAct = QAction(QIcon(':/images/save.png'), "&Save", self,
shortcut=QKeySequence.Save,
statusTip="Save the document to disk", triggered=self.save)
self.saveAsAct = QAction("Save &As...", self,
shortcut=QKeySequence.SaveAs,
statusTip="Save the document under a new name",
triggered=self.saveAs)
self.exitAct = QAction("E&xit", self, shortcut=QKeySequence.Quit,
statusTip="Exit the application",
triggered=QApplication.instance().closeAllWindows)
self.cutAct = QAction(QIcon(':/images/cut.png'), "Cu&t", self,
shortcut=QKeySequence.Cut,
statusTip="Cut the current selection's contents to the clipboard",
triggered=self.cut)
self.copyAct = QAction(QIcon(':/images/copy.png'), "&Copy", self,
shortcut=QKeySequence.Copy,
statusTip="Copy the current selection's contents to the clipboard",
triggered=self.copy)
self.pasteAct = QAction(QIcon(':/images/paste.png'), "&Paste", self,
shortcut=QKeySequence.Paste,
statusTip="Paste the clipboard's contents into the current selection",
triggered=self.paste)
self.closeAct = QAction("Cl&ose", self,
statusTip="Close the active window",
triggered=self.mdiArea.closeActiveSubWindow)
self.closeAllAct = QAction("Close &All", self,
statusTip="Close all the windows",
triggered=self.mdiArea.closeAllSubWindows)
self.tileAct = QAction("&Tile", self, statusTip="Tile the windows",
triggered=self.mdiArea.tileSubWindows)
self.cascadeAct = QAction("&Cascade", self,
statusTip="Cascade the windows",
triggered=self.mdiArea.cascadeSubWindows)
self.nextAct = QAction("Ne&xt", self, shortcut=QKeySequence.NextChild,
statusTip="Move the focus to the next window",
triggered=self.mdiArea.activateNextSubWindow)
self.previousAct = QAction("Pre&vious", self,
shortcut=QKeySequence.PreviousChild,
statusTip="Move the focus to the previous window",
triggered=self.mdiArea.activatePreviousSubWindow)
self.separatorAct = QAction(self)
self.separatorAct.setSeparator(True)
self.aboutAct = QAction("&About", self,
statusTip="Show the application's About box",
triggered=self.about)
self.aboutQtAct = QAction("About &Qt", self,
statusTip="Show the Qt library's About box",
triggered=QApplication.instance().aboutQt)
def createMenus(self):
self.fileMenu = self.menuBar().addMenu("&File")
self.fileMenu.addAction(self.newAct)
self.fileMenu.addAction(self.openAct)
self.fileMenu.addAction(self.saveAct)
self.fileMenu.addAction(self.saveAsAct)
self.fileMenu.addSeparator()
action = self.fileMenu.addAction("Switch layout direction")
action.triggered.connect(self.switchLayoutDirection)
self.fileMenu.addAction(self.exitAct)
self.editMenu = self.menuBar().addMenu("&Edit")
self.editMenu.addAction(self.cutAct)
self.editMenu.addAction(self.copyAct)
self.editMenu.addAction(self.pasteAct)
self.windowMenu = self.menuBar().addMenu("&Window")
self.updateWindowMenu()
self.windowMenu.aboutToShow.connect(self.updateWindowMenu)
self.menuBar().addSeparator()
self.helpMenu = self.menuBar().addMenu("&Help")
self.helpMenu.addAction(self.aboutAct)
self.helpMenu.addAction(self.aboutQtAct)
def createToolBars(self):
self.fileToolBar = self.addToolBar("File")
self.fileToolBar.addAction(self.newAct)
self.fileToolBar.addAction(self.openAct)
self.fileToolBar.addAction(self.saveAct)
self.editToolBar = self.addToolBar("Edit")
self.editToolBar.addAction(self.cutAct)
self.editToolBar.addAction(self.copyAct)
self.editToolBar.addAction(self.pasteAct)
def createStatusBar(self):
self.statusBar().showMessage("Ready")
def readSettings(self):
settings = QSettings('Trolltech', 'MDI Example')
pos = settings.value('pos', QPoint(200, 200))
size = settings.value('size', QSize(400, 400))
self.move(pos)
self.resize(size)
def writeSettings(self):
settings = QSettings('Trolltech', 'MDI Example')
settings.setValue('pos', self.pos())
settings.setValue('size', self.size())
def activeMdiChild(self):
activeSubWindow = self.mdiArea.activeSubWindow()
if activeSubWindow:
return activeSubWindow.widget()
return None
def findMdiChild(self, fileName):
canonicalFilePath = QFileInfo(fileName).canonicalFilePath()
for window in self.mdiArea.subWindowList():
if window.widget().currentFile() == canonicalFilePath:
return window
return None
def switchLayoutDirection(self):
if self.layoutDirection() == Qt.LeftToRight:
QApplication.setLayoutDirection(Qt.RightToLeft)
else:
QApplication.setLayoutDirection(Qt.LeftToRight)
def setActiveSubWindow(self, window):
if window:
self.mdiArea.setActiveSubWindow(window)
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
mainWin = MainWindow()
mainWin.show()
sys.exit(app.exec_())
Useful links
- Learn PyQt: https://pythonbasics.org/pyqt-hello-world/
- Install PyQt: https://pythonbasics.org/install-pyqt/