Article Outline
Python pyqt (gui) example 'schema'
Functions in program:
def decode_utf8(qs):def encode_utf8(ba):
Modules used in program:
import schema_rc
schema
Python pyqt example: schema
#!/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 QByteArray, QFile, QRegExp, Qt
from PyQt5.QtGui import (QColor, QFont, QSyntaxHighlighter, QTextCharFormat,
QTextCursor, QTextFormat)
from PyQt5.QtWidgets import QApplication, QMainWindow, QTextEdit
from PyQt5.QtXmlPatterns import (QAbstractMessageHandler, QSourceLocation,
QXmlSchema, QXmlSchemaValidator)
import schema_rc
from ui_schema import Ui_SchemaMainWindow
def encode_utf8(ba):
try:
return unicode(ba, encoding='utf8')
except NameError:
return str(ba, encoding='utf8')
def decode_utf8(qs):
try:
return QByteArray(qs.decode(encoding='utf8'))
except AttributeError:
return QByteArray(bytes(qs, encoding='utf8'))
class XmlSyntaxHighlighter(QSyntaxHighlighter):
def __init__(self, parent=None):
super(XmlSyntaxHighlighter, self).__init__(parent)
self.highlightingRules = []
# Tag format.
format = QTextCharFormat()
format.setForeground(Qt.darkBlue)
format.setFontWeight(QFont.Bold)
pattern = QRegExp("(<[a-zA-Z:]+\\b|<\\?[a-zA-Z:]+\\b|\\?>|>|/>|</[a-zA-Z:]+>)")
self.highlightingRules.append((pattern, format))
# Attribute format.
format = QTextCharFormat()
format.setForeground(Qt.darkGreen)
pattern = QRegExp("[a-zA-Z:]+=")
self.highlightingRules.append((pattern, format))
# Attribute content format.
format = QTextCharFormat()
format.setForeground(Qt.red)
pattern = QRegExp("(\"[^\"]*\"|'[^']*')")
self.highlightingRules.append((pattern, format))
# Comment format.
self.commentFormat = QTextCharFormat()
self.commentFormat.setForeground(Qt.lightGray)
self.commentFormat.setFontItalic(True)
self.commentStartExpression = QRegExp("<!--")
self.commentEndExpression = QRegExp("-->")
def highlightBlock(self, text):
for pattern, format in self.highlightingRules:
expression = QRegExp(pattern)
index = expression.indexIn(text)
while index >= 0:
length = expression.matchedLength()
self.setFormat(index, length, format)
index = expression.indexIn(text, index + length)
self.setCurrentBlockState(0)
startIndex = 0
if self.previousBlockState() != 1:
startIndex = self.commentStartExpression.indexIn(text)
while startIndex >= 0:
endIndex = self.commentEndExpression.indexIn(text, startIndex)
if endIndex == -1:
self.setCurrentBlockState(1)
commentLength = text.length() - startIndex
else:
commentLength = endIndex - startIndex + self.commentEndExpression.matchedLength()
self.setFormat(startIndex, commentLength, self.commentFormat)
startIndex = self.commentStartExpression.indexIn(text,
startIndex + commentLength)
class MessageHandler(QAbstractMessageHandler):
def __init__(self):
super(MessageHandler, self).__init__()
self.m_description = ""
self.m_sourceLocation = QSourceLocation()
def statusMessage(self):
return self.m_description
def line(self):
return self.m_sourceLocation.line()
def column(self):
return self.m_sourceLocation.column()
def handleMessage(self, type, description, identifier, sourceLocation):
self.m_description = description
self.m_sourceLocation = sourceLocation
class MainWindow(QMainWindow, Ui_SchemaMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.setupUi(self)
XmlSyntaxHighlighter(self.schemaView.document())
XmlSyntaxHighlighter(self.instanceEdit.document())
self.schemaSelection.addItem("Contact Schema")
self.schemaSelection.addItem("Recipe Schema")
self.schemaSelection.addItem("Order Schema")
self.instanceSelection.addItem("Valid Contact Instance")
self.instanceSelection.addItem("Invalid Contact Instance")
self.schemaSelection.currentIndexChanged.connect(self.schemaSelected)
self.instanceSelection.currentIndexChanged.connect(self.instanceSelected)
self.validateButton.clicked.connect(self.validate)
self.instanceEdit.textChanged.connect(self.textChanged)
self.validationStatus.setAlignment(Qt.AlignCenter | Qt.AlignVCenter)
self.schemaSelected(0)
self.instanceSelected(0)
def schemaSelected(self, index):
self.instanceSelection.clear()
if index == 0:
self.instanceSelection.addItem("Valid Contact Instance")
self.instanceSelection.addItem("Invalid Contact Instance")
elif index == 1:
self.instanceSelection.addItem("Valid Recipe Instance")
self.instanceSelection.addItem("Invalid Recipe Instance")
elif index == 2:
self.instanceSelection.addItem("Valid Order Instance")
self.instanceSelection.addItem("Invalid Order Instance")
self.textChanged()
schemaFile = QFile(':/schema_%d.xsd' % index)
schemaFile.open(QFile.ReadOnly)
schemaData = schemaFile.readAll()
self.schemaView.setPlainText(encode_utf8(schemaData))
self.validate()
def instanceSelected(self, index):
index += 2 * self.schemaSelection.currentIndex()
instanceFile = QFile(':/instance_%d.xml' % index)
instanceFile.open(QFile.ReadOnly)
instanceData = instanceFile.readAll()
self.instanceEdit.setPlainText(encode_utf8(instanceData))
self.validate()
def validate(self):
schemaData = decode_utf8(self.schemaView.toPlainText())
instanceData = decode_utf8(self.instanceEdit.toPlainText())
messageHandler = MessageHandler()
schema = QXmlSchema()
schema.setMessageHandler(messageHandler)
schema.load(schemaData)
errorOccurred = False
if not schema.isValid():
errorOccurred = True
else:
validator = QXmlSchemaValidator(schema)
if not validator.validate(instanceData):
errorOccurred = True
if errorOccurred:
self.validationStatus.setText(messageHandler.statusMessage())
self.moveCursor(messageHandler.line(), messageHandler.column())
background = Qt.red
else:
self.validationStatus.setText("validation successful")
background = Qt.green
styleSheet = 'QLabel {background: %s; padding: 3px}' % QColor(background).lighter(160).name()
self.validationStatus.setStyleSheet(styleSheet)
def textChanged(self):
self.instanceEdit.setExtraSelections([])
def moveCursor(self, line, column):
self.instanceEdit.moveCursor(QTextCursor.Start)
for i in range(1, line):
self.instanceEdit.moveCursor(QTextCursor.Down)
for i in range(1, column):
self.instanceEdit.moveCursor(QTextCursor.Right)
extraSelections = []
selection = QTextEdit.ExtraSelection()
lineColor = QColor(Qt.red).lighter(160)
selection.format.setBackground(lineColor)
selection.format.setProperty(QTextFormat.FullWidthSelection, True)
selection.cursor = self.instanceEdit.textCursor()
selection.cursor.clearSelection()
extraSelections.append(selection)
self.instanceEdit.setExtraSelections(extraSelections)
self.instanceEdit.setFocus()
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())
Useful links
- Learn PyQt: https://pythonbasics.org/pyqt-hello-world/
- Install PyQt: https://pythonbasics.org/install-pyqt/