python3+PyQt5泛型委托详解

自定义委托可以让我们对视图中出现的数据项的外观和行为进行完全控制。如果有很多模型，可能会希望不是全部的大多数模型能够仅用一个自定义委托，如果不能这么做，那么对于这些自定义委托，将很有可能存在大量重复代码。为了使得维护工作变得轻松，更好的方法为不要为每个模型创建一个自定义委托，而是用一系列的通用组件来共同构成一个委托。本文通过Python3+pyqt5实现了python Qt GUI 快速编程的16章的泛型委托例子。

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

#!/usr/bin/env python3import platformimport sysimport htmlfrom PyQt5.QtCore import QSize, Qt,pyqtSignalfrom PyQt5.QtGui import QColor, QFont,QFontMetrics, QIcon, QKeySequence, QPixmap,QTextCharFormatfrom PyQt5.QtWidgets import QAction,QApplication,QMenu,QTextEditclass 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 <b>Ctrl+M</b> for the text effects "    "menu and <b>Ctrl+K</b> 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 = "<sub>{0}</sub>".format(text)     elif (format.verticalAlignment() ==       QTextCharFormat.AlignSuperScript):      text = "<sup>{0}</sup>".format(text)     if format.fontUnderline():      text = "<u>{0}</u>".format(text)     if format.fontItalic():      text = "<i>{0}</i>".format(text)     if format.fontWeight() > QFont.Normal:      text = "<b>{0}</b>".format(text)     if format.fontStrikeOut():      text = "<s>{0}</s>".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 = "<font{0}>{1}</font>".format(attribs,text)     htmltext += text    iterator += 1   block = block.next()  return htmltextif __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_()