Article Outline
Python pyqt (gui) example 'sdi'
Modules used in program:
import sdi_rc
sdi
Python pyqt example: sdi
#!/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.
##
## 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."
## $QT_END_LICENSE$
##
#############################################################################
from PyQt5.QtCore import (QFile, QFileInfo, QPoint, QSettings, QSize, Qt,
QTextStream)
from PyQt5.QtGui import QIcon, QKeySequence
from PyQt5.QtWidgets import (QAction, QApplication, QFileDialog, QMainWindow,
QMessageBox, QTextEdit)
import sdi_rc
class MainWindow(QMainWindow):
sequenceNumber = 1
windowList = []
def __init__(self, fileName=None):
super(MainWindow, self).__init__()
self.init()
if fileName:
self.loadFile(fileName)
else:
self.setCurrentFile('')
def closeEvent(self, event):
if self.maybeSave():
self.writeSettings()
event.accept()
else:
event.ignore()
def newFile(self):
other = MainWindow()
MainWindow.windowList.append(other)
other.move(self.x() + 40, self.y() + 40)
other.show()
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self)
if fileName:
existing = self.findMainWindow(fileName)
if existing:
existing.show()
existing.raise_()
existing.activateWindow()
return
if self.isUntitled and self.textEdit.document().isEmpty() and not self.isWindowModified():
self.loadFile(fileName)
else:
other = MainWindow(fileName)
if other.isUntitled:
del other
return
MainWindow.windowList.append(other)
other.move(self.x() + 40, self.y() + 40)
other.show()
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 about(self):
QMessageBox.about(self, "About SDI",
"The <b>SDI</b> example demonstrates how to write single "
"document interface applications using Qt.")
def documentWasModified(self):
self.setWindowModified(True)
def init(self):
self.setAttribute(Qt.WA_DeleteOnClose)
self.isUntitled = True
self.textEdit = QTextEdit()
self.setCentralWidget(self.textEdit)
self.createActions()
self.createMenus()
self.createToolBars()
self.createStatusBar()
self.readSettings()
self.textEdit.document().contentsChanged.connect(self.documentWasModified)
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.closeAct = QAction("&Close", self, shortcut="Ctrl+W",
statusTip="Close this window", triggered=self.close)
self.exitAct = QAction("E&xit", self, shortcut="Ctrl+Q",
statusTip="Exit the application",
triggered=QApplication.instance().closeAllWindows)
self.cutAct = QAction(QIcon(':/images/cut.png'), "Cu&t", self,
enabled=False, shortcut=QKeySequence.Cut,
statusTip="Cut the current selection's contents to the clipboard",
triggered=self.textEdit.cut)
self.copyAct = QAction(QIcon(':/images/copy.png'), "&Copy", self,
enabled=False, shortcut=QKeySequence.Copy,
statusTip="Copy the current selection's contents to the clipboard",
triggered=self.textEdit.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.textEdit.paste)
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)
self.textEdit.copyAvailable.connect(self.cutAct.setEnabled)
self.textEdit.copyAvailable.connect(self.copyAct.setEnabled)
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()
self.fileMenu.addAction(self.closeAct)
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.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', 'SDI 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', 'SDI Example')
settings.setValue('pos', self.pos())
settings.setValue('size', self.size())
def maybeSave(self):
if self.textEdit.document().isModified():
ret = QMessageBox.warning(self, "SDI",
"The document has been modified.\nDo you want to save "
"your changes?",
QMessageBox.Save | QMessageBox.Discard |
QMessageBox.Cancel)
if ret == QMessageBox.Save:
return self.save()
if ret == QMessageBox.Cancel:
return False
return True
def loadFile(self, fileName):
file = QFile(fileName)
if not file.open(QFile.ReadOnly | QFile.Text):
QMessageBox.warning(self, "SDI",
"Cannot read file %s:\n%s." % (fileName, file.errorString()))
return
instr = QTextStream(file)
QApplication.setOverrideCursor(Qt.WaitCursor)
self.textEdit.setPlainText(instr.readAll())
QApplication.restoreOverrideCursor()
self.setCurrentFile(fileName)
self.statusBar().showMessage("File loaded", 2000)
def saveFile(self, fileName):
file = QFile(fileName)
if not file.open(QFile.WriteOnly | QFile.Text):
QMessageBox.warning(self, "SDI",
"Cannot write file %s:\n%s." % (fileName, file.errorString()))
return False
outstr = QTextStream(file)
QApplication.setOverrideCursor(Qt.WaitCursor)
outstr << self.textEdit.toPlainText()
QApplication.restoreOverrideCursor()
self.setCurrentFile(fileName)
self.statusBar().showMessage("File saved", 2000)
return True
def setCurrentFile(self, fileName):
self.isUntitled = not fileName
if self.isUntitled:
self.curFile = "document%d.txt" % MainWindow.sequenceNumber
MainWindow.sequenceNumber += 1
else:
self.curFile = QFileInfo(fileName).canonicalFilePath()
self.textEdit.document().setModified(False)
self.setWindowModified(False)
self.setWindowTitle("%s[*] - SDI" % self.strippedName(self.curFile))
def strippedName(self, fullFileName):
return QFileInfo(fullFileName).fileName()
def findMainWindow(self, fileName):
canonicalFilePath = QFileInfo(fileName).canonicalFilePath()
for widget in QApplication.instance().topLevelWidgets():
if isinstance(widget, MainWindow) and widget.curFile == canonicalFilePath:
return widget
return None
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/