python - QStyledItemDelegate 水平截断文本并且不添加水平滚动条

Question

我得到了以下代码，我稍作修改，作为 how to use HTML formatted text in a QListWidget 的答案.

ma​​in.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Dialog</class>
 <widget class="QDialog" name="Dialog">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>341</width>
    <height>161</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Dialog</string>
  </property>
  <widget class="QWidget" name="verticalLayoutWidget">
   <property name="geometry">
    <rect>
     <x>10</x>
     <y>10</y>
     <width>321</width>
     <height>141</height>
    </rect>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="QListWidget" name="lwOptions"/>
    </item>
   </layout>
  </widget>
 </widget>
 <resources/>
 <connections/>
</ui>

测试.py

import os
import html
from PyQt5 import uic
from PyQt5.Qt import (QApplication, QDialog, QListWidget, 
    QListWidgetItem, QStyleOptionViewItem, 
    QStyledItemDelegate, QStyle)
from PyQt5.QtGui import QPalette, QAbstractTextDocumentLayout, QTextDocument
from PyQt5.QtCore import QSize

class HTMLDelegate(QStyledItemDelegate):
    def __init__(self, parent=None):
        super(HTMLDelegate, self).__init__(parent)
        self.doc = QTextDocument(self)

    def paint(self, painter, option, index):
        painter.save()
        options = QStyleOptionViewItem(option)
        self.initStyleOption(options, index)
        self.doc.setHtml(options.text)
        options.text = ""
        style = QApplication.style() if options.widget is None \
            else options.widget.style()
        style.drawControl(QStyle.CE_ItemViewItem, options, painter)

        ctx = QAbstractTextDocumentLayout.PaintContext()
        if option.state & QStyle.State_Selected:
            ctx.palette.setColor(QPalette.Text, option.palette.color(
                QPalette.Active, QPalette.HighlightedText))
        else:
            ctx.palette.setColor(QPalette.Text, option.palette.color(
                QPalette.Active, QPalette.Text))
        textRect = style.subElementRect(QStyle.SE_ItemViewItemText, options, None)
        if index.column() != 0:
            textRect.adjust(5, 0, 0, 0)
        constant = 4
        margin = (option.rect.height() - options.fontMetrics.height()) // 2
        margin = margin - constant
        textRect.setTop(textRect.top() + margin)

        painter.translate(textRect.topLeft())
        painter.setClipRect(textRect.translated(-textRect.topLeft()))
        self.doc.documentLayout().draw(painter, ctx)
        painter.restore()

    def sizeHint(self, option, index):
        return QSize(self.doc.idealWidth(), self.doc.size().height())

class GUI(QDialog):
    def __init__(self):
        super(GUI, self).__init__()
        dirname = os.path.dirname(os.path.abspath(__file__))
        uic.loadUi(os.path.join(dirname,'main.ui'), self)

        delegate = HTMLDelegate(self.lwOptions)
        self.lwOptions.setItemDelegate(delegate)

        for ordinal in ['first', 'second', 'third', 'fourth', 'fifth', 'sixth', 'seventh', 'eighth', 'ninth']:
            item = QListWidgetItem('This is the <b>{}</b> word. This is the <b>{}</b> word. This is the <b>{}</b> word.'.format(ordinal, ordinal, ordinal))
            self.lwOptions.addItem(item)


if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    window = GUI()
    window.show()
    sys.exit(app.exec_())

代码工作正常，但是，长度超过 QListWidget 宽度的文本会被截断，并且不会显示水平滚动条。(需要时会自动添加垂直滚动条。)

我尝试通过 ScrollBarAlwaysOn 强制显示，它只显示一个不起作用的水平滚动条。

我需要如何更改代码才能在需要时自动添加水平滚动条？

Answer 1

我在之前的答案中进行的计算不正确，因为返回 sizeHint() 的大小是相对于前一项的。一个简单的解决方案是使用 Qt::SizeHintRole 角色来设置大小。

import os
from PyQt5 import QtCore, QtGui, QtWidgets, uic

class HTMLDelegate(QtWidgets.QStyledItemDelegate):
    def __init__(self, parent=None):
        super(HTMLDelegate, self).__init__(parent)
        self.doc = QtGui.QTextDocument(self)

    def paint(self, painter, option, index):
        painter.save()
        options = QtWidgets.QStyleOptionViewItem(option)
        self.initStyleOption(options, index)
        self.doc.setHtml(options.text)
        options.text = ""
        style = QApplication.style() if options.widget is None \
            else options.widget.style()
        style.drawControl(QtWidgets.QStyle.CE_ItemViewItem, options, painter)

        ctx = QtGui.QAbstractTextDocumentLayout.PaintContext()
        if option.state & QtWidgets.QStyle.State_Selected:
            ctx.palette.setColor(QtGui.QPalette.Text, option.palette.color(
                QtGui.QPalette.Active, QtGui.QPalette.HighlightedText))
        else:
            ctx.palette.setColor(QtGui.QPalette.Text, option.palette.color(
                QtGui.QPalette.Active, QtGui.QPalette.Text))
        textRect = style.subElementRect(QtWidgets.QStyle.SE_ItemViewItemText, options, None)
        if index.column() != 0:
            textRect.adjust(5, 0, 0, 0)
        constant = 4
        margin = (option.rect.height() - options.fontMetrics.height()) // 2
        margin = margin - constant
        textRect.setTop(textRect.top() + margin)

        painter.translate(textRect.topLeft())
        painter.setClipRect(textRect.translated(-textRect.topLeft()))
        self.doc.documentLayout().draw(painter, ctx)
        painter.restore()
        s = QtCore.QSize(self.doc.idealWidth(), self.doc.size().height())
        index.model().setData(index, s, QtCore.Qt.SizeHintRole)

class GUI(QtWidgets.QDialog):
    def __init__(self):
        super(GUI, self).__init__()
        dirname = os.path.dirname(os.path.abspath(__file__))
        uic.loadUi(os.path.join(dirname,'main.ui'), self)

        delegate = HTMLDelegate(self.lwOptions)
        self.lwOptions.setItemDelegate(delegate)

        for ordinal in ['first', 'second', 'third', 'fourth', 'fifth', 'sixth', 'seventh', 'eighth', 'ninth']:
            item = QtWidgets.QListWidgetItem('This is the <b>{}</b> word. This is the <b>{}</b> word. This is the <b>{}</b> word.'.format(ordinal, ordinal, ordinal))
            self.lwOptions.addItem(item)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = GUI()
    window.show()
    sys.exit(app.exec_())