Article Outline
Python pyqt (gui) example 'previewer'
previewer
Python pyqt example: previewer
#!/usr/bin/env python
#############################################################################
##
## Copyright (C) 2013 Riverbank Computing Limited
## Copyright (C) 2010 Hans-Peter Jansen <[email protected]>.
## 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,
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## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
## $QT_END_LICENSE$
##
###########################################################################
from PyQt5.QtCore import QFile, QIODevice, QTextStream, QUrl
from PyQt5.QtGui import QKeySequence
from PyQt5.QtWidgets import (QAction, QApplication, QFileDialog, QInputDialog,
QLineEdit, QMainWindow, QMessageBox, QWidget)
from ui_previewer import Ui_Form
class Previewer(QWidget, Ui_Form):
def __init__(self, parent=None):
super(Previewer, self).__init__(parent)
self.setupUi(self)
self.baseUrl = QUrl()
def setBaseUrl(self, url):
self.baseUrl = url
def on_previewButton_clicked(self):
# Update the contents in the web viewer.
text = self.plainTextEdit.toPlainText()
self.webView.setHtml(text, self.baseUrl)
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.createActions()
self.createMenus()
self.centralWidget = Previewer(self)
self.setCentralWidget(self.centralWidget)
self.centralWidget.webView.loadFinished.connect(self.updateTextEdit)
self.setStartupText()
def createActions(self):
self.openAct = QAction("&Open...", self, shortcut=QKeySequence.Open,
statusTip="Open an existing HTML file", triggered=self.open)
self.openUrlAct = QAction("&Open URL...", self, shortcut="Ctrl+U",
statusTip="Open a URL", triggered=self.openUrl)
self.saveAct = QAction("&Save", self, shortcut=QKeySequence.Save,
statusTip="Save the HTML file to disk", triggered=self.save)
self.exitAct = QAction("E&xit", self, shortcut=QKeySequence.Quit,
statusTip="Exit the application", triggered=self.close)
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.openAct)
self.fileMenu.addAction(self.openUrlAct)
self.fileMenu.addAction(self.saveAct)
self.fileMenu.addSeparator()
self.fileMenu.addAction(self.exitAct)
self.menuBar().addSeparator()
self.helpMenu = self.menuBar().addMenu("&Help")
self.helpMenu.addAction(self.aboutAct)
self.helpMenu.addAction(self.aboutQtAct)
def about(self):
QMessageBox.about(self, "About Previewer",
"The <b>Previewer</b> example demonstrates how to view HTML "
"documents using a QtWebKitWidgets.QWebView.")
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self)
if fileName:
fd = QFile(fileName)
if not fd.open(QIODevice.ReadOnly):
QMessageBox.information(self, "Unable to open file",
fd.errorString())
return
output = QTextStream(fd).readAll()
# Display contents.
self.centralWidget.plainTextEdit.setPlainText(output)
self.centralWidget.setBaseUrl(QUrl.fromLocalFile(fileName))
def openUrl(self):
url, ok = QInputDialog.getText(self, "Enter a URL", "URL:",
QLineEdit.Normal, "http://")
if ok and url:
url = QUrl(url)
self.centralWidget.webView.setUrl(url)
def save(self):
content = self.centralWidget.plainTextEdit.toPlainText()
fileName, _ = QFileDialog.getSaveFileName(self)
if fileName:
fd = QFile(fileName)
if not fd.open(QIODevice.WriteOnly):
QMessageBox.information(self, "Unable to open file",
fd.errorString())
return
QTextStream(fd) << content
def updateTextEdit(self):
mainFrame = self.centralWidget.webView.page().mainFrame()
frameText = mainFrame.toHtml()
self.centralWidget.plainTextEdit.setPlainText(frameText)
def setStartupText(self):
self.centralWidget.webView.setHtml("""
<html><body>
<h1>HTML Previewer</h1>
<p>This example shows you how to use QtWebKitWidgets.QWebView to
preview HTML data written in a QtWidgets.QPlainTextEdit.
</p>
</body></html>""")
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
mainWindow = MainWindow()
mainWindow.show()
sys.exit(app.exec_())
Useful links
- Learn PyQt: https://pythonbasics.org/pyqt-hello-world/
- Install PyQt: https://pythonbasics.org/install-pyqt/