Detailed explanation of python3+PyQt5 generic delegation

This article mainly introduces the relevant information of python3 PyQt5 generic delegation to everyone in detail. It has certain reference value. Interested friends can refer to it.

Custom delegation allows us to view the view. Take full control over the appearance and behavior of data items that appear in . If you have a lot of models, you may want to be able to use just one custom delegate for most of the models, but if you can't do that, you will most likely have a lot of duplicate code for those custom delegates. To make maintenance easier, a better approach is not to create a custom delegate for each model, but to use a series of common components that together form a delegate. This article implements the generic delegation example of Chapter 16 of python Qt GUI rapid programming through Python3 pyqt5.

/home/yrd/eric_workspace/chap16/richtextlineedit.py

#!/usr/bin/env python3

import platform
import sys
import html
from PyQt5.QtCore import QSize, Qt,pyqtSignal
from PyQt5.QtGui import QColor, QFont,QFontMetrics, QIcon, QKeySequence, QPixmap,QTextCharFormat
from PyQt5.QtWidgets import QAction,QApplication,QMenu,QTextEdit


class RichTextLineEdit(QTextEdit):
 returnPressed=pyqtSignal()
 (Bold, Italic, Underline, StrikeOut, Monospaced, Sans, Serif,
  NoSuperOrSubscript, Subscript, Superscript) = range(10)


 def __init__(self, parent=None):
  super(RichTextLineEdit, self).__init__(parent)

  self.monofamily = "courier"
  self.sansfamily = "helvetica"
  self.seriffamily = "times"
  self.setLineWrapMode(QTextEdit.NoWrap)
  self.setTabChangesFocus(True)
  self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
  self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
  fm = QFontMetrics(self.font())
  h = int(fm.height() * (1.4 if platform.system() == "Windows"
         else 1.2))
  self.setMinimumHeight(h)
  self.setMaximumHeight(int(h * 1.2))
  self.setToolTip("Press Ctrl+M for the text effects "
    "menu and Ctrl+K for the color menu")


 def toggleItalic(self):
  self.setFontItalic(not self.fontItalic())


 def toggleUnderline(self):
  self.setFontUnderline(not self.fontUnderline())


 def toggleBold(self):
  self.setFontWeight(QFont.Normal
    if self.fontWeight() > QFont.Normal else QFont.Bold)


 def sizeHint(self):
  return QSize(self.document().idealWidth() + 5,
      self.maximumHeight())


 def minimumSizeHint(self):
  fm = QFontMetrics(self.font())
  return QSize(fm.width("WWWW"), self.minimumHeight())


 def contextMenuEvent(self, event):
  self.textEffectMenu()


 def keyPressEvent(self, event):
  if event.modifiers() & Qt.ControlModifier:
   handled = False
   if event.key() == Qt.Key_B:
    self.toggleBold()
    handled = True
   elif event.key() == Qt.Key_I:
    self.toggleItalic()
    handled = True
   elif event.key() == Qt.Key_K:
    self.colorMenu()
    handled = True
   elif event.key() == Qt.Key_M:
    self.textEffectMenu()
    handled = True
   elif event.key() == Qt.Key_U:
    self.toggleUnderline()
    handled = True
   if handled:
    event.accept()
    return
  if event.key() in (Qt.Key_Enter, Qt.Key_Return):
   self.returnPressed.emit()
   event.accept()
  else:
   QTextEdit.keyPressEvent(self, event)


 def colorMenu(self):
  pixmap = QPixmap(22, 22)
  menu = QMenu("Colour")
  for text, color in (
    ("&Black", Qt.black),
    ("B&lue", Qt.blue),
    ("Dark Bl&ue", Qt.darkBlue),
    ("&Cyan", Qt.cyan),
    ("Dar&k Cyan", Qt.darkCyan),
    ("&Green", Qt.green),
    ("Dark Gr&een", Qt.darkGreen),
    ("M&agenta", Qt.magenta),
    ("Dark Mage&nta", Qt.darkMagenta),
    ("&Red", Qt.red),
    ("&Dark Red", Qt.darkRed)):
   color = QColor(color)
   pixmap.fill(color)
   action = menu.addAction(QIcon(pixmap), text, self.setColor)
   action.setData(color)
  self.ensureCursorVisible()
  menu.exec_(self.viewport().mapToGlobal(
     self.cursorRect().center()))


 def setColor(self):
  action = self.sender()
  if action is not None and isinstance(action, QAction):
   color = QColor(action.data())
   if color.isValid():
    self.setTextColor(color)


 def textEffectMenu(self):
  format = self.currentCharFormat()
  menu = QMenu("Text Effect")
  for text, shortcut, data, checked in (
    ("&Bold", "Ctrl+B", RichTextLineEdit.Bold,
     self.fontWeight() > QFont.Normal),
    ("&Italic", "Ctrl+I", RichTextLineEdit.Italic,
     self.fontItalic()),
    ("Strike &out", None, RichTextLineEdit.StrikeOut,
     format.fontStrikeOut()),
    ("&Underline", "Ctrl+U", RichTextLineEdit.Underline,
     self.fontUnderline()),
    ("&Monospaced", None, RichTextLineEdit.Monospaced,
     format.fontFamily() == self.monofamily),
    ("&Serifed", None, RichTextLineEdit.Serif,
     format.fontFamily() == self.seriffamily),
    ("S&ans Serif", None, RichTextLineEdit.Sans,
     format.fontFamily() == self.sansfamily),
    ("&No super or subscript", None,
     RichTextLineEdit.NoSuperOrSubscript,
     format.verticalAlignment() ==
     QTextCharFormat.AlignNormal),
    ("Su&perscript", None, RichTextLineEdit.Superscript,
     format.verticalAlignment() ==
     QTextCharFormat.AlignSuperScript),
    ("Subs&cript", None, RichTextLineEdit.Subscript,
     format.verticalAlignment() ==
     QTextCharFormat.AlignSubScript)):
   action = menu.addAction(text, self.setTextEffect)
   if shortcut is not None:
    action.setShortcut(QKeySequence(shortcut))
   action.setData(data)
   action.setCheckable(True)
   action.setChecked(checked)
  self.ensureCursorVisible()
  menu.exec_(self.viewport().mapToGlobal(
     self.cursorRect().center()))


 def setTextEffect(self):
  action = self.sender()
  if action is not None and isinstance(action, QAction):
   what = action.data()
   if what == RichTextLineEdit.Bold:
    self.toggleBold()
    return
   if what == RichTextLineEdit.Italic:
    self.toggleItalic()
    return
   if what == RichTextLineEdit.Underline:
    self.toggleUnderline()
    return
   format = self.currentCharFormat()
   if what == RichTextLineEdit.Monospaced:
    format.setFontFamily(self.monofamily)
   elif what == RichTextLineEdit.Serif:
    format.setFontFamily(self.seriffamily)
   elif what == RichTextLineEdit.Sans:
    format.setFontFamily(self.sansfamily)
   if what == RichTextLineEdit.StrikeOut:
    format.setFontStrikeOut(not format.fontStrikeOut())
   if what == RichTextLineEdit.NoSuperOrSubscript:
    format.setVerticalAlignment(
      QTextCharFormat.AlignNormal)
   elif what == RichTextLineEdit.Superscript:
    format.setVerticalAlignment(
      QTextCharFormat.AlignSuperScript)
   elif what == RichTextLineEdit.Subscript:
    format.setVerticalAlignment(
      QTextCharFormat.AlignSubScript)
   self.mergeCurrentCharFormat(format)


 def toSimpleHtml(self):
  htmltext = ""
  black = QColor(Qt.black)
  block = self.document().begin()
  while block.isValid():
   iterator = block.begin()
   while iterator != block.end():
    fragment = iterator.fragment()
    if fragment.isValid():
     format = fragment.charFormat()
     family = format.fontFamily()
     color = format.foreground().color()     
     text=html.escape(fragment.text())
     if (format.verticalAlignment() ==
      QTextCharFormat.AlignSubScript):
      text = "{0}".format(text)
     elif (format.verticalAlignment() ==
       QTextCharFormat.AlignSuperScript):
      text = "{0}".format(text)
     if format.fontUnderline():
      text = "{0}".format(text)
     if format.fontItalic():
      text = "{0}".format(text)
     if format.fontWeight() > QFont.Normal:
      text = "{0}".format(text)
     if format.fontStrikeOut():
      text = "{0}".format(text)
     if color != black or family:
      attribs = ""
      if color != black:
       attribs += ' color="{0}"'.format(color.name())
      if family:
       attribs += ' face="{0}"'.format(family)
      text = "{1}".format(attribs,text)
     htmltext += text
    iterator += 1
   block = block.next()
  return htmltext

if __name__ == "__main__":
 def printout(lineedit):
  print(str(lineedit.toHtml()))
  print(str(lineedit.toPlainText()))
  print(str(lineedit.toSimpleHtml()))    
 app = QApplication(sys.argv)
 lineedit = RichTextLineEdit()
 lineedit.returnPressed.connect(lambda:printout(lineedit))
 lineedit.show()
 lineedit.setWindowTitle("RichTextEdit")
 app.exec_()

/home/yrd/eric_workspace/chap16/genericdelegates .py

#!/usr/bin/env python3

from PyQt5.QtCore import (QDate, QSize, Qt)
from PyQt5.QtWidgets import (QApplication, QDateEdit, QLineEdit,
  QSpinBox, QStyledItemDelegate,QStyle)
from PyQt5.QtGui import QColor,QTextDocument
import richtextlineedit


class GenericDelegate(QStyledItemDelegate):

 def __init__(self, parent=None):
  super(GenericDelegate, self).__init__(parent)
  self.delegates = {}


 def insertColumnDelegate(self, column, delegate):
  delegate.setParent(self)
  self.delegates[column] = delegate


 def removeColumnDelegate(self, column):
  if column in self.delegates:
   del self.delegates[column]


 def paint(self, painter, option, index):
  delegate = self.delegates.get(index.column())
  if delegate is not None:
   delegate.paint(painter, option, index)
  else:
   QStyledItemDelegate.paint(self, painter, option, index)


 def createEditor(self, parent, option, index):
  delegate = self.delegates.get(index.column())
  if delegate is not None:
   return delegate.createEditor(parent, option, index)
  else:
   return QStyledItemDelegate.createEditor(self, parent, option,
             index)


 def setEditorData(self, editor, index):
  delegate = self.delegates.get(index.column())
  if delegate is not None:
   delegate.setEditorData(editor, index)
  else:
   QStyledItemDelegate.setEditorData(self, editor, index)


 def setModelData(self, editor, model, index):
  delegate = self.delegates.get(index.column())
  if delegate is not None:
   delegate.setModelData(editor, model, index)
  else:
   QStyledItemDelegate.setModelData(self, editor, model, index)


class IntegerColumnDelegate(QStyledItemDelegate):

 def __init__(self, minimum=0, maximum=100, parent=None):
  super(IntegerColumnDelegate, self).__init__(parent)
  self.minimum = minimum
  self.maximum = maximum


 def createEditor(self, parent, option, index):
  spinbox = QSpinBox(parent)
  spinbox.setRange(self.minimum, self.maximum)
  spinbox.setAlignment(Qt.AlignRight|Qt.AlignVCenter)
  return spinbox


 def setEditorData(self, editor, index):
  value = index.model().data(index, Qt.DisplayRole)
  editor.setValue(value)


 def setModelData(self, editor, model, index):
  editor.interpretText()
  model.setData(index, editor.value())


class DateColumnDelegate(QStyledItemDelegate):

 def __init__(self, minimum=QDate(),
     maximum=QDate.currentDate(),
     format="yyyy-MM-dd", parent=None):
  super(DateColumnDelegate, self).__init__(parent)
  self.minimum = minimum
  self.maximum = maximum
  self.format = format


 def createEditor(self, parent, option, index):
  dateedit = QDateEdit(parent)
  #dateedit=QDateTimeEdit(parent)
  dateedit.setDateRange(self.minimum, self.maximum)
  dateedit.setAlignment(Qt.AlignRight|Qt.AlignVCenter)
  dateedit.setDisplayFormat(self.format)
  dateedit.setCalendarPopup(True)
  return dateedit


 def setEditorData(self, editor, index):
  value = index.model().data(index, Qt.DisplayRole)
  #if value.isNull:
  editor.setDate(value)
  #editor.setDisplayFormat(self.format)

 def setModelData(self, editor, model, index):
  model.setData(index, editor.date())
 def paint(self, painter, option, index):
  text = index.model().data(index, Qt.DisplayRole).toString(self.format)
  palette = QApplication.palette()
  document = QTextDocument()
  document.setDefaultFont(option.font)
  if option.state & QStyle.State_Selected:
   document.setHtml("{1}".format(palette.highlightedText().color().name(),text))
  else:
   document.setHtml(text)
  painter.save()
  color = (palette.highlight().color()
     if option.state & QStyle.State_Selected
     else QColor(index.model().data(index,
        Qt.BackgroundColorRole)))
  painter.fillRect(option.rect, color)
  painter.translate(option.rect.x(), option.rect.y())
  document.drawContents(painter)
  painter.restore()  


class PlainTextColumnDelegate(QStyledItemDelegate):

 def __init__(self, parent=None):
  super(PlainTextColumnDelegate, self).__init__(parent)


 def createEditor(self, parent, option, index):
  lineedit = QLineEdit(parent)
  return lineedit


 def setEditorData(self, editor, index):
  value = index.model().data(index, Qt.DisplayRole)
  editor.setText(value)


 def setModelData(self, editor, model, index):
  model.setData(index, editor.text())


class RichTextColumnDelegate(QStyledItemDelegate):

 def __init__(self, parent=None):
  super(RichTextColumnDelegate, self).__init__(parent)


 def paint(self, painter, option, index):
  text = index.model().data(index, Qt.DisplayRole)
  palette = QApplication.palette()
  document = QTextDocument()
  document.setDefaultFont(option.font)
  if option.state & QStyle.State_Selected:
   document.setHtml("{1}".format(palette.highlightedText().color().name(),text))
  else:
   document.setHtml(text)
  painter.save()
  color = (palette.highlight().color()
     if option.state & QStyle.State_Selected
     else QColor(index.model().data(index,
        Qt.BackgroundColorRole)))
  painter.fillRect(option.rect, color)
  painter.translate(option.rect.x(), option.rect.y())
  document.drawContents(painter)
  painter.restore()


 def sizeHint(self, option, index):
  text = index.model().data(index).toString()
  document = QTextDocument()
  document.setDefaultFont(option.font)
  document.setHtml(text)
  return QSize(document.idealWidth() + 5,
      option.fontMetrics.height())


 def createEditor(self, parent, option, index):
  lineedit = richtextlineedit.RichTextLineEdit(parent)
  return lineedit


 def setEditorData(self, editor, index):
  value = index.model().data(index, Qt.DisplayRole)
  editor.setHtml(value)


 def setModelData(self, editor, model, index):
  model.setData(index, editor.toSimpleHtml())

/home/yrd/eric_workspace/chap16/carhirelog.pyw

#!/usr/bin/env python3

import bisect
import os
import platform
import sys
from PyQt5.QtCore import (QAbstractTableModel, QDate, QModelIndex,
  QVariant, Qt,pyqtSignal)
from PyQt5.QtWidgets import (QApplication, QMainWindow,
  QShortcut, QTableView)
from PyQt5.QtGui import QKeySequence
import genericdelegates


(LICENSE, CUSTOMER, HIRED, MILEAGEOUT, RETURNED, MILEAGEBACK,
 NOTES, MILEAGE, DAYS) = range(9)


class CarHireLog(object):

 def __init__(self, license, customer, hired, mileageout,
     returned=QDate(), mileageback=0, notes=""):
  self.license = license  # plain text
  self.customer = customer # plain text
  self.hired = hired     # QDate
  self.mileageout = mileageout   # int
  self.returned = returned    # QDate
  self.mileageback = mileageback  # int
  self.notes = notes   # HTML


 def field(self, column):
  if column == LICENSE:
   return self.license
  elif column == CUSTOMER:
   return self.customer
  elif column == HIRED:
   return self.hired
  elif column == MILEAGEOUT:
   return self.mileageout
  elif column == RETURNED:
   return self.returned
  elif column == MILEAGEBACK:
   return self.mileageback
  elif column == NOTES:
   return self.notes
  elif column == MILEAGE:
   return self.mileage()
  elif column == DAYS:
   return self.days()
  assert False


 def mileage(self):
  return (0 if self.mileageback == 0
     else self.mileageback - self.mileageout)


 def days(self):
  return (0 if not self.returned.isValid()
     else self.hired.daysTo(self.returned))


 def __hash__(self):
  return super(CarHireLog, self).__hash__()


 def __eq__(self, other):
  if self.hired != other.hired:
   return False
  if self.customer != other.customer:
   return False
  if self.license != other.license:
   return False
  return id(self) == id(other)


 def __lt__(self, other):
  if self.hired < other.hired:
   return True
  if self.customer < other.customer:
   return True
  if self.license < other.license:
   return True
  return id(self) < id(other)


class CarHireModel(QAbstractTableModel):
 dataChanged = pyqtSignal(QModelIndex,QModelIndex)
 def __init__(self, parent=None):
  super(CarHireModel, self).__init__(parent)
  self.logs = []

  # Generate fake data
  import gzip
  import random
  import string
  surname_data = gzip.open(os.path.join(
    os.path.dirname(__file__), "surnames.txt.gz")).read()
  surnames = surname_data.decode("utf8").splitlines()
  years = ("06 ", "56 ", "07 ", "57 ", "08 ", "58 ")
  titles = ("Ms ", "Mr ", "Ms ", "Mr ", "Ms ", "Mr ", "Dr ")
  notetexts = ("Returned damaged",
    "Returned with empty fuel tank",
    "Customer complained about the engine",
    "Customer complained about the gears",
    "Customer complained about the clutch",
    "Returned dirty",)
  today = QDate.currentDate()
  for i in range(250):
   license = []
   for c in range(5):
    license.append(random.choice(string.ascii_uppercase))
   license = ("".join(license[:2]) + random.choice(years) +
      "".join(license[2:]))
   customer = random.choice(titles) + random.choice(surnames)
   hired = today.addDays(-random.randint(0, 365))
   mileageout = random.randint(10000, 30000)
   notes = ""
   if random.random() >= 0.2:
    days = random.randint(1, 21)
    returned = hired.addDays(days)
    mileageback = (mileageout +
        (days * random.randint(30, 300)))
    if random.random() > 0.75:
     notes = random.choice(notetexts)
   else:
    returned = QDate()
    mileageback = 0
   log = CarHireLog(license, customer, hired, mileageout,
        returned, mileageback, notes)
   bisect.insort(self.logs, log)


 def rowCount(self, index=QModelIndex()):
  return len(self.logs)


 def columnCount(self, index=QModelIndex()):
  return 9


 def data(self, index, role):
  if not index.isValid():
   return QVariant()
  if role == Qt.DisplayRole:
   log = self.logs[index.row()]
   value = log.field(index.column())
   if (index.column() in (MILEAGEBACK, MILEAGE, DAYS) and
    value == 0):
    return 0
   return value
  if (role == Qt.TextAlignmentRole and
   index.column() not in (LICENSE, CUSTOMER, NOTES)):
   return QVariant(int(Qt.AlignRight|Qt.AlignVCenter))
  if role == Qt.BackgroundColorRole:
   palette = QApplication.palette()
   if index.column() in (LICENSE, MILEAGE, DAYS):
    return QVariant(palette.alternateBase())
   else:
    return QVariant(palette.base())
  return QVariant()


 def setData(self, index, value, role=Qt.EditRole):
  if (index.isValid() and role == Qt.EditRole and
   index.column() not in (LICENSE, MILEAGE, DAYS)):
   log = self.logs[index.row()]
   column = index.column()
   if column == CUSTOMER:
    log.customer = value
   elif column == HIRED:
    #log.hired = value.toDate()
    log.hired = value
   elif column == MILEAGEOUT:
    log.mileageout = value
   elif column == RETURNED:
    #log.returned = value.toDate()
    log.returned = value
   elif column == MILEAGEBACK:
    log.mileageback = value
   elif column == NOTES:
    log.notes = value
   self.dataChanged[QModelIndex,QModelIndex].emit(index,index)
   return True
  return False


 def headerData(self, section, orientation, role):
  if role == Qt.TextAlignmentRole:
   if orientation == Qt.Horizontal:
    return QVariant(int(Qt.AlignCenter))
   return QVariant(int(Qt.AlignRight|Qt.AlignVCenter))
  if role != Qt.DisplayRole:
   return QVariant()
  if orientation == Qt.Horizontal:
   if section == LICENSE:
    return "License"
   elif section == CUSTOMER:
    return "Customer"
   elif section == HIRED:
    return "Hired"
   elif section == MILEAGEOUT:
    return "Mileage #1"
   elif section == RETURNED:
    return "Returned"
   elif section == MILEAGEBACK:
    return "Mileage #2"
   elif section == DAYS:
    return "Days"
   elif section == MILEAGE:
    return "Miles"
   elif section == NOTES:
    return "Notes"
  return section + 1


 def flags(self, index):
  flag = QAbstractTableModel.flags(self, index)
  if index.column() not in (LICENSE, MILEAGE, DAYS):
   flag |= Qt.ItemIsEditable
  return flag


class HireDateColumnDelegate(genericdelegates.DateColumnDelegate):

 def createEditor(self, parent, option, index):
  i = index.sibling(index.row(), RETURNED)
  self.maximum = i.model().data(i, Qt.DisplayRole).addDays(-1)
  return genericdelegates.DateColumnDelegate.createEditor(
    self, parent, option, index)


class ReturnDateColumnDelegate(genericdelegates.DateColumnDelegate):

 def createEditor(self, parent, option, index):
  i = index.sibling(index.row(), HIRED)
  self.minimum = i.model().data(i, Qt.DisplayRole).addDays(1)
  return genericdelegates.DateColumnDelegate.createEditor(
    self, parent, option, index)


class MileageOutColumnDelegate(genericdelegates.IntegerColumnDelegate):

 def createEditor(self, parent, option, index):
  i = index.sibling(index.row(), MILEAGEBACK)
  maximum = i.model().data(i, Qt.DisplayRole)
  self.maximum = 1000000 if maximum == 0 else maximum - 1
  return genericdelegates.IntegerColumnDelegate.createEditor(
    self, parent, option, index)


class MileageBackColumnDelegate(genericdelegates.IntegerColumnDelegate):

 def createEditor(self, parent, option, index):
  i = index.sibling(index.row(), MILEAGEOUT)
  self.minimum = i.model().data(i, Qt.DisplayRole) + 1
  return genericdelegates.IntegerColumnDelegate.createEditor(
    self, parent, option, index)


class MainForm(QMainWindow):

 def __init__(self, parent=None):
  super(MainForm, self).__init__(parent)

  model = CarHireModel(self)

  self.view = QTableView()
  self.view.setModel(model)
  self.view.resizeColumnsToContents()

  delegate = genericdelegates.GenericDelegate(self)
  delegate.insertColumnDelegate(CUSTOMER,
    genericdelegates.PlainTextColumnDelegate())
  earliest = QDate.currentDate().addYears(-3)
  delegate.insertColumnDelegate(HIRED,
    HireDateColumnDelegate(earliest))
  delegate.insertColumnDelegate(MILEAGEOUT,
    MileageOutColumnDelegate(0, 1000000))
  delegate.insertColumnDelegate(RETURNED,
    ReturnDateColumnDelegate(earliest))
  delegate.insertColumnDelegate(MILEAGEBACK,
    MileageBackColumnDelegate(0, 1000000))
  delegate.insertColumnDelegate(NOTES,
    genericdelegates.RichTextColumnDelegate())

  self.view.setItemDelegate(delegate)
  self.setCentralWidget(self.view)

  QShortcut(QKeySequence("Escape"), self, self.close)
  QShortcut(QKeySequence("Ctrl+Q"), self, self.close)

  self.setWindowTitle("Car Hire Logs")


app = QApplication(sys.argv)
form = MainForm()
rect = QApplication.desktop().availableGeometry()
form.resize(int(rect.width() * 0.7), int(rect.height() * 0.8))
form.move(0, 0)
form.show()
app.exec_()

Running results:

python3 PyQt5 implements a page indexer application that supports multi-threading

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