python3+PyQt5 实现Rich文本的行编辑方法

本文通过Python3+PyQt5实现《python Qt Gui 快速编程》这本书13章程序Rich文本的行编辑，可以通过鼠标右键选择对文本进行加粗，斜体，下划线，删除线，上标，下标等编辑。

#!/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 <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 = "_{0}".format(text)
         elif (format.verticalAlignment() ==
            QTextCharFormat.AlignSuperScript):
           text = "^{0}".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 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_()

来源：https://blog.csdn.net/xiaoyangyang20/article/details/68924261