text: #!/usr/bin/env python
  
  
  #############################################################################
  ##
  ## Copyright (C) 2010 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."
  ## $QT_END_LICENSE$
  ##
  #############################################################################
  
  
  # This is only needed for Python v2 but is harmless for Python v3.
  import sip
  sip.setapi('QVariant', 2)
  
  from PyQt4 import QtCore, QtGui
  
  try:
      import sdi_rc3
  except ImportError:
      import sdi_rc2
  
  
  class MainWindow(QtGui.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 = QtGui.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 = QtGui.QFileDialog.getSaveFileName(self, "Save As",
                  self.curFile)
          if not fileName:
              return False
  
          return self.saveFile(fileName)
  
      def about(self):
          QtGui.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(QtCore.Qt.WA_DeleteOnClose)
          self.isUntitled = True
          self.textEdit = QtGui.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 = QtGui.QAction(QtGui.QIcon(':/images/new.png'), "&New",
                  self, shortcut=QtGui.QKeySequence.New,
                  statusTip="Create a new file", triggered=self.newFile)
  
          self.openAct = QtGui.QAction(QtGui.QIcon(':/images/open.png'),
                  "&Open...", self, shortcut=QtGui.QKeySequence.Open,
                  statusTip="Open an existing file", triggered=self.open)
  
          self.saveAct = QtGui.QAction(QtGui.QIcon(':/images/save.png'),
                  "&Save", self, shortcut=QtGui.QKeySequence.Save,
                  statusTip="Save the document to disk", triggered=self.save)
  
          self.saveAsAct = QtGui.QAction("Save &As...", self,
                  shortcut=QtGui.QKeySequence.SaveAs,
                  statusTip="Save the document under a new name",
                  triggered=self.saveAs)
  
          self.closeAct = QtGui.QAction("&Close", self, shortcut="Ctrl+W",
                  statusTip="Close this window", triggered=self.close)
  
          self.exitAct = QtGui.QAction("E&xit", self, shortcut="Ctrl+Q",
                  statusTip="Exit the application",
                  triggered=QtGui.qApp.closeAllWindows)
  
          self.cutAct = QtGui.QAction(QtGui.QIcon(':/images/cut.png'), "Cu&t",
                  self, enabled=False, shortcut=QtGui.QKeySequence.Cut,
                  statusTip="Cut the current selection's contents to the clipboard",
                  triggered=self.textEdit.cut)
  
          self.copyAct = QtGui.QAction(QtGui.QIcon(':/images/copy.png'),
                  "&Copy", self, enabled=False, shortcut=QtGui.QKeySequence.Copy,
                  statusTip="Copy the current selection's contents to the clipboard",
                  triggered=self.textEdit.copy)
  
          self.pasteAct = QtGui.QAction(QtGui.QIcon(':/images/paste.png'),
                  "&Paste", self, shortcut=QtGui.QKeySequence.Paste,
                  statusTip="Paste the clipboard's contents into the current selection",
                  triggered=self.textEdit.paste)
  
          self.aboutAct = QtGui.QAction("&About", self,
                  statusTip="Show the application's About box",
                  triggered=self.about)
  
          self.aboutQtAct = QtGui.QAction("About &Qt", self,
                  statusTip="Show the Qt library's About box",
                  triggered=QtGui.qApp.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 = QtCore.QSettings('Trolltech', 'SDI Example')
          pos = settings.value('pos', QtCore.QPoint(200, 200))
          size = settings.value('size', QtCore.QSize(400, 400))
          self.move(pos)
          self.resize(size)
  
      def writeSettings(self):
          settings = QtCore.QSettings('Trolltech', 'SDI Example')
          settings.setValue('pos', self.pos())
          settings.setValue('size', self.size())
  
      def maybeSave(self):
          if self.textEdit.document().isModified():
              ret = QtGui.QMessageBox.warning(self, "SDI",
                      "The document has been modified.\nDo you want to save "
                      "your changes?",
                      QtGui.QMessageBox.Save | QtGui.QMessageBox.Discard |
                      QtGui.QMessageBox.Cancel)
              if ret == QtGui.QMessageBox.Save:
                  return self.save()
              elif ret == QtGui.QMessageBox.Cancel:
                  return False
          return True
  
      def loadFile(self, fileName):
          file = QtCore.QFile(fileName)
          if not file.open( QtCore.QFile.ReadOnly | QtCore.QFile.Text):
              QtGui.QMessageBox.warning(self, "SDI",
                      "Cannot read file %s:\n%s." % (fileName, file.errorString()))
              return
  
          instr = QtCore.QTextStream(file)
          QtGui.QApplication.setOverrideCursor(QtCore.Qt.WaitCursor)
          self.textEdit.setPlainText(instr.readAll())
          QtGui.QApplication.restoreOverrideCursor()
  
          self.setCurrentFile(fileName)
          self.statusBar().showMessage("File loaded", 2000)
  
      def saveFile(self, fileName):
          file = QtCore.QFile(fileName)
          if not file.open( QtCore.QFile.WriteOnly | QtCore.QFile.Text):
              QtGui.QMessageBox.warning(self, "SDI",
                      "Cannot write file %s:\n%s." % (fileName, file.errorString()))
              return False
  
          outstr = QtCore.QTextStream(file)
          QtGui.QApplication.setOverrideCursor(QtCore.Qt.WaitCursor)
          outstr << self.textEdit.toPlainText()
          QtGui.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 = QtCore.QFileInfo(fileName).canonicalFilePath()
  
          self.textEdit.document().setModified(False)
          self.setWindowModified(False)
  
          self.setWindowTitle("%s[*] - SDI" % self.strippedName(self.curFile))
  
      def strippedName(self, fullFileName):
          return QtCore.QFileInfo(fullFileName).fileName()
  
      def findMainWindow(self, fileName):
          canonicalFilePath = QtCore.QFileInfo(fileName).canonicalFilePath()
  
          for widget in QtGui.qApp.topLevelWidgets():
              if isinstance(widget, MainWindow) and widget.curFile == canonicalFilePath:
                  return widget
  
          return None
  
  
  if __name__ == '__main__':
  
      import sys
  
      app = QtGui.QApplication(sys.argv)
      mainWin = MainWindow()
      mainWin.show()
      sys.exit(app.exec_())
  