Article Outline
Python pyqt (gui) example 'codecs'
Functions in program:
def codec_name(codec):
codecs
Python pyqt example: codecs
#!/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
## 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
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## $QT_END_LICENSE$
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#############################################################################
from PyQt5.QtCore import QFile, QRegExp, QTextCodec, QTextStream
from PyQt5.QtWidgets import (QAction, QApplication, QComboBox, QDialog,
QDialogButtonBox, QFileDialog, QGridLayout, QLabel, QMainWindow, QMenu,
QMessageBox, QTextEdit)
def codec_name(codec):
try:
# Python v3.
name = str(codec.name(), encoding='ascii')
except TypeError:
# Python v2.
name = str(codec.name())
return name
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.textEdit = QTextEdit()
self.textEdit.setLineWrapMode(QTextEdit.NoWrap)
self.setCentralWidget(self.textEdit)
self.codecs = []
self.findCodecs()
self.previewForm = PreviewForm(self)
self.previewForm.setCodecList(self.codecs)
self.saveAsActs = []
self.createActions()
self.createMenus()
self.setWindowTitle("Codecs")
self.resize(500, 400)
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self)
if fileName:
inFile = QFile(fileName)
if not inFile.open(QFile.ReadOnly):
QMessageBox.warning(self, "Codecs",
"Cannot read file %s:\n%s" % (fileName, inFile.errorString()))
return
data = inFile.readAll()
self.previewForm.setEncodedData(data)
if self.previewForm.exec_():
self.textEdit.setPlainText(self.previewForm.decodedString())
def save(self):
fileName, _ = QFileDialog.getSaveFileName(self)
if fileName:
outFile = QFile(fileName)
if not outFile.open(QFile.WriteOnly|QFile.Text):
QMessageBox.warning(self, "Codecs",
"Cannot write file %s:\n%s" % (fileName, outFile.errorString()))
return
action = self.sender()
codecName = action.data()
out = QTextStream(outFile)
out.setCodec(codecName)
out << self.textEdit.toPlainText()
def about(self):
QMessageBox.about(self, "About Codecs",
"The <b>Codecs</b> example demonstrates how to read and "
"write files using various encodings.")
def aboutToShowSaveAsMenu(self):
currentText = self.textEdit.toPlainText()
for action in self.saveAsActs:
codecName = action.data()
codec = QTextCodec.codecForName(codecName)
action.setVisible(codec and codec.canEncode(currentText))
def findCodecs(self):
codecMap = []
iso8859RegExp = QRegExp('ISO[- ]8859-([0-9]+).*')
for mib in QTextCodec.availableMibs():
codec = QTextCodec.codecForMib(mib)
sortKey = codec_name(codec).upper()
rank = 0
if sortKey.startswith('UTF-8'):
rank = 1
elif sortKey.startswith('UTF-16'):
rank = 2
elif iso8859RegExp.exactMatch(sortKey):
if len(iso8859RegExp.cap(1)) == 1:
rank = 3
else:
rank = 4
else:
rank = 5
codecMap.append((str(rank) + sortKey, codec))
codecMap.sort()
self.codecs = [item[-1] for item in codecMap]
def createActions(self):
self.openAct = QAction("&Open...", self, shortcut="Ctrl+O",
triggered=self.open)
for codec in self.codecs:
name = codec_name(codec)
action = QAction(name + '...', self, triggered=self.save)
action.setData(name)
self.saveAsActs.append(action)
self.exitAct = QAction("E&xit", self, shortcut="Ctrl+Q",
triggered=self.close)
self.aboutAct = QAction("&About", self, triggered=self.about)
self.aboutQtAct = QAction("About &Qt", self,
triggered=QApplication.instance().aboutQt)
def createMenus(self):
self.saveAsMenu = QMenu("&Save As", self)
for action in self.saveAsActs:
self.saveAsMenu.addAction(action)
self.saveAsMenu.aboutToShow.connect(self.aboutToShowSaveAsMenu)
self.fileMenu = QMenu("&File", self)
self.fileMenu.addAction(self.openAct)
self.fileMenu.addMenu(self.saveAsMenu)
self.fileMenu.addSeparator()
self.fileMenu.addAction(self.exitAct)
self.helpMenu = QMenu("&Help", self)
self.helpMenu.addAction(self.aboutAct)
self.helpMenu.addAction(self.aboutQtAct)
self.menuBar().addMenu(self.fileMenu)
self.menuBar().addSeparator()
self.menuBar().addMenu(self.helpMenu)
class PreviewForm(QDialog):
def __init__(self, parent):
super(PreviewForm, self).__init__(parent)
self.encodingComboBox = QComboBox()
encodingLabel = QLabel("&Encoding:")
encodingLabel.setBuddy(self.encodingComboBox)
self.textEdit = QTextEdit()
self.textEdit.setLineWrapMode(QTextEdit.NoWrap)
self.textEdit.setReadOnly(True)
buttonBox = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
self.encodingComboBox.activated.connect(self.updateTextEdit)
buttonBox.accepted.connect(self.accept)
buttonBox.rejected.connect(self.reject)
mainLayout = QGridLayout()
mainLayout.addWidget(encodingLabel, 0, 0)
mainLayout.addWidget(self.encodingComboBox, 0, 1)
mainLayout.addWidget(self.textEdit, 1, 0, 1, 2)
mainLayout.addWidget(buttonBox, 2, 0, 1, 2)
self.setLayout(mainLayout)
self.setWindowTitle("Choose Encoding")
self.resize(400, 300)
def setCodecList(self, codecs):
self.encodingComboBox.clear()
for codec in codecs:
self.encodingComboBox.addItem(codec_name(codec), codec.mibEnum())
def setEncodedData(self, data):
self.encodedData = data
self.updateTextEdit()
def decodedString(self):
return self.decodedStr
def updateTextEdit(self):
mib = self.encodingComboBox.itemData(self.encodingComboBox.currentIndex())
codec = QTextCodec.codecForMib(mib)
data = QTextStream(self.encodedData)
data.setAutoDetectUnicode(False)
data.setCodec(codec)
self.decodedStr = data.readAll()
self.textEdit.setPlainText(self.decodedStr)
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/