如何使用 QStyledItemDelegate 进行 paint()

Question

我正在使用 PySide2，我找不到任何关于如何在 QStyledItemDelegate 子类中使用 paint() 函数的文档。 我对课程很陌生，但到目前为止可以理解，但在使用 PySide2 时遇到了麻烦。

我想用我自己的 ListWidgetItem 替换我的 QtWidgets.QListWidgetItem 并正确显示它们，如下所示：

因此，在 ListWidgetItem 的左侧有一个图标，在 ListWidgetItem 的名称右侧和描述下方。

这是代码：

from PySide2 import QtWidgets, QtCore, QtGui
from PySide2.QtGui import *
import sys

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__()

        self.setWindowTitle('Test Window')
        self.setStyleSheet("background-color: rgb(65, 65, 65);")

        mainWidget = QtWidgets.QWidget(self)
        self.setCentralWidget(mainWidget)
        self.boxLayout = QtWidgets.QVBoxLayout()
        mainWidget.setLayout(self.boxLayout)

        # Add Widgets
        self.textField = QtWidgets.QLineEdit()
        self.listView = QtWidgets.QListWidget()

        self.textField.textChanged.connect(self.onTextChanged)

        self.boxLayout.addWidget(self.textField)
        self.boxLayout.addWidget(self.listView)

        self.textField.setFocus()


    def onTextChanged(self, ):
        titles = ['Monkey', 'Giraffe', 'Dragon', 'Bull']
        descriptions = ['Almost a homo sapiens sapiens', 'I am a Giraffe!', 'Can fly and is hot on spices', 'Horny...']

        if self.textField.text() == '' or self.textField.text().isspace() or self.textField.text() == ' ':
            if self.listView.count() > 0:
                self.listView.clear()
        else:
            if self.listView.count() > 0:
                self.listView.clear()
            for x in range(len(titles)):
                if self.textField.text() in titles[x]:
                    item = ListWidgetItem(titles[x])
                    self.listView.addItem(item)
                    self.listView.setCurrentRow(0)
                    continue


class ListWidgetItem(QtWidgets.QListWidgetItem):
    def __init__(self, title = '', description = '', icon = QtGui.QIcon()):
        super(ListWidgetItem, self).__init__()
        self.title = title
        self.description = description
        self.icon = icon


class ListViewStyle(QtWidgets.QStyledItemDelegate):
    def __init__(self, parent, itemModel):
        super(ListViewStyle, self).__init__(parent)
        self.itemModel = itemModel

    def sizeHint(self, option, index):
        if index:
            return QtCore.QSize(40, 40)

    def paint(self, painter, option, index):
        super(ListViewStyle, self).paint(painter, option, index)

if __name__ == '__main__':
    app = QtWidgets.QApplication.instance()
    if app is None: 
        app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()
    w.show()
    #sys.exit(app.exec_())

信息：在 onTextChanged() 中，ListWidgetItem 将被添加到 QListWidget 但未正确绘制，基本上是空的。

QListWidgetItem 与 QListView 有什么显着区别吗？

Answer 1

委托只绘制并且对提供信息的元素不感兴趣，因为该类使用 QModelIndex 和相同的模型来获取信息，所以在我之前的解决方案中，我使用了一个使用 QStandardItem 的 QStandardItemModel，在你当前的情况下，一个 QListWidget 和 QListWidgetItem无动于衷。 我的委托只希望标题、描述和图标的信息分别与 TitleRole、DescriptionRole 和 IconRole 相关。

另一方面，删除项目并不好，但最好在必要时隐藏或使它们可见。

综上所述，使用QListWidget的解决方案如下：

import sys

from PySide2 import QtWidgets, QtCore, QtGui

TitleRole = QtCore.Qt.UserRole + 1000
DescriptionRole = QtCore.Qt.UserRole + 1001
IconRole = QtCore.Qt.UserRole + 1002


class ListWidgetItem(QtWidgets.QListWidgetItem):
    def __init__(self, title="", description="", icon=QtGui.QIcon()):
        super(ListWidgetItem, self).__init__()
        self.title = title
        self.description = description
        self.icon = icon

    @property
    def title(self):
        return self.data(TitleRole)

    @title.setter
    def title(self, title):
        self.setData(TitleRole, title)

    @property
    def description(self):
        return self.data(DescriptionRole)

    @description.setter
    def description(self, description):
        self.setData(DescriptionRole, description)

    @property
    def icon(self):
        return self.data(IconRole)

    @icon.setter
    def icon(self, icon):
        self.setData(IconRole, icon)


class StyledItemDelegate(QtWidgets.QStyledItemDelegate):
    def sizeHint(self, option, index):
        return QtCore.QSize(50, 50)

    def paint(self, painter, option, index):
        super(StyledItemDelegate, self).paint(painter, option, index)
        title = index.data(TitleRole)
        description = index.data(DescriptionRole)
        icon = index.data(IconRole)

        mode = QtGui.QIcon.Normal
        if not (option.state & QtWidgets.QStyle.State_Enabled):
            mode = QtGui.QIcon.Disabled
        elif option.state & QtWidgets.QStyle.State_Selected:
            mode = QtGui.QIcon.Selected

        state = (
            QtGui.QIcon.On
            if option.state & QtWidgets.QStyle.State_Open
            else QtGui.QIcon.Off
        )
        iconRect = QtCore.QRect(option.rect)
        iconRect.setSize(QtCore.QSize(40, 40))
        icon.paint(
            painter, iconRect, QtCore.Qt.AlignLeft | QtCore.Qt.AlignVCenter, mode, state
        )

        titleFont = QtGui.QFont(option.font)
        titleFont.setPixelSize(20)
        fm = QtGui.QFontMetrics(titleFont)
        titleRect = QtCore.QRect(option.rect)
        titleRect.setLeft(iconRect.right())
        titleRect.setHeight(fm.height())

        color = (
            option.palette.color(QtGui.QPalette.BrightText)
            if option.state & QtWidgets.QStyle.State_Selected
            else option.palette.color(QtGui.QPalette.WindowText)
        )
        painter.save()
        painter.setFont(titleFont)
        pen = painter.pen()
        pen.setColor(color)
        painter.setPen(pen)
        painter.drawText(titleRect, title)
        painter.restore()

        descriptionFont = QtGui.QFont(option.font)
        descriptionFont.setPixelSize(15)
        fm = QtGui.QFontMetrics(descriptionFont)
        descriptionRect = QtCore.QRect(option.rect)
        descriptionRect.setTopLeft(titleRect.bottomLeft())
        descriptionRect.setHeight(fm.height())
        painter.save()
        painter.setFont(descriptionFont)
        pen = painter.pen()
        pen.setColor(color)
        painter.setPen(pen)
        painter.drawText(
            descriptionRect,
            fm.elidedText(description, QtCore.Qt.ElideRight, descriptionRect.width()),
        )
        painter.restore()


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__()

        self.setWindowTitle("Test Window")
        self.setStyleSheet("background-color: rgb(65, 65, 65);")

        mainWidget = QtWidgets.QWidget(self)
        self.setCentralWidget(mainWidget)
        self.boxLayout = QtWidgets.QVBoxLayout()
        mainWidget.setLayout(self.boxLayout)

        # Add Widgets
        self.textField = QtWidgets.QLineEdit()
        self.listView = QtWidgets.QListWidget()

        self.textField.textChanged.connect(self.onTextChanged)

        self.boxLayout.addWidget(self.textField)
        self.boxLayout.addWidget(self.listView)
        self.fill_model()

        self.textField.setFocus()

        self.listView.setItemDelegate(StyledItemDelegate(self))

    def fill_model(self):
        titles = ["Monkey", "Giraffe", "Dragon", "Bull"]
        descriptions = [
            "Almost a homo sapiens sapiens",
            "I am a Giraffe!",
            "Can fly and is hot on spices",
            "Horny...",
        ]

        for title, description in zip(titles, descriptions):
            it = ListWidgetItem(title=title, description=description)
            self.listView.addItem(it)

    @QtCore.Slot(str)
    def onTextChanged(self, text):
        text = text.strip()
        if text:
            for i in range(self.listView.count()):
                it = self.listView.item(i)
                if it is not None:
                    it.setHidden(text.lower() not in it.title.lower())
        else:
            for i in range(self.listView.count()):
                it = self.listView.item(i)
                if it is not None:
                    it.setHidden(False)


if __name__ == "__main__":
    app = QtWidgets.QApplication.instance()
    if app is None:
        app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())