详解如何在PyQt5中实现平滑滚动的QScrollArea

讲解如何在PyQt5中实现平滑滚动的QScrollArea的完整攻略包括以下几个步骤：

1. 创建QScrollArea对象：使用PyQt5中的QScrollArea模块，创建一个QScrollArea对象。例如，可以在PyQt5的主窗口中添加一个QScrollArea控件。

import sys
from PyQt5 import QtWidgets, QtGui

class Example(QtWidgets.QMainWindow):

    def __init__(self):
        super().__init__()

        scroll = QtWidgets.QScrollArea(self)
        self.setCentralWidget(scroll)

        # 添加需要滚动的内容

app = QtWidgets.QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())

1. 设置滚动条的属性：为了实现平滑滚动，需要将QScrollBar的属性“singleStep”设置为较小的值。该属性指滚动条的单步距离，默认值为“120”。将值修改为10-20可以实现更平滑的滚动。

scroll.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
scroll.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

scroll_widget = QtWidgets.QWidget()
# 添加需要滚动的内容至scroll_widget中
scroll_widget.setGeometry(QtCore.QRect(0, 0, 800, 1100)) # 大小需要与实际内容大小匹配

scroll.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
scroll.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

vbar = scroll.verticalScrollBar()
vbar.setMaximum(scroll_widget.height())
vbar.setSingleStep(10)

scroll.setWidget(scroll_widget)

1. 实现平滑滚动：定义一个滚动条滚动事件的回调函数，使得QScrollArea在滚动时产生一个平滑滚动的效果。这里需要借助QScrollArea的scrollContentsBy()方法实现滚动的效果。

def scrollEvent(self, event):
    vbar = self.verticalScrollBar()
    val = event.angleDelta().y()

    vbar.setValue(vbar.value() - (val/15)*vbar.singleStep())

    event.accept()

scroll.verticalScrollBar().valueChanged.connect(scrollEvent)

以上就是实现平滑滚动的完整攻略。以下是两个例子以展示该攻略的使用。

示例1：实现图片的平滑滚动

import sys
from PyQt5 import QtWidgets, QtGui, QtCore

class Example(QtWidgets.QMainWindow):

    def __init__(self):
        super().__init__()

        scroll = QtWidgets.QScrollArea(self)
        self.setCentralWidget(scroll)

        scroll_widget = QtWidgets.QWidget()
        self.gridLayout = QtWidgets.QGridLayout(scroll_widget)

        for i in range(10):
            for j in range(10):
                btn = QtWidgets.QPushButton(self)
                icon = QtGui.QIcon('image.png')
                btn.setIcon(icon)
                self.gridLayout.addWidget(btn, i, j)

        scroll_widget.setGeometry(QtCore.QRect(0, 0, 800, 1100))
        scroll.setWidgetResizable(False)
        scroll.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
        scroll.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

        vbar = scroll.verticalScrollBar()
        vbar.setMaximum(scroll_widget.height())
        vbar.setSingleStep(10)
        scroll.setWidget(scroll_widget)

    def scrollEvent(self, event):
        vbar = self.verticalScrollBar()
        val = event.angleDelta().y()

        vbar.setValue(vbar.value() - (val/15)*vbar.singleStep())
        event.accept()

app = QtWidgets.QApplication(sys.argv)
ex = Example()
ex.show()
ex.scroll.verticalScrollBar().valueChanged.connect(ex.scrollEvent)
sys.exit(app.exec_())

示例2：实现文本的平滑滚动

import sys
from PyQt5 import QtWidgets, QtGui, QtCore

class Example(QtWidgets.QMainWindow):

    def __init__(self):
        super().__init__()

        scroll = QtWidgets.QScrollArea(self)
        self.setCentralWidget(scroll)

        scroll_widget = QtWidgets.QWidget()
        self.verticalLayout = QtWidgets.QVBoxLayout(scroll_widget)

        text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. ' \
               'Etiam dictum quam vel ante pharetra iaculis. Sed efficitur ' \
               'nisi eu neque ullamcorper, et tincidunt lectus posuere. ' \
               'Praesent feugiat posuere neque, eget rutrum odio bibendum vitae. ' \
               'Sed lobortis consequat massa vitae bibendum. Fusce vitae elementum erat. ' \
               'Suspendisse eu lectus id nisl scelerisque pharetra. Etiam ' \
               'eu massa nec diam volutpat venenatis. Integer eget bibendum quam. ' \
               'Nulla facilisi. Vivamus dapibus, arcu at elementum cursus, lectus ' \
               'lectus aliquet nulla, vitae blandit orci velit nec metus. Nullam ' \
               'dignissim scelerisque lacinia. Sed lobortis rutrum arcu, in volutpat ' \
               'nunc pretium eu.\n' \

        label = QtWidgets.QLabel(scroll_widget)
        label.setText(text)
        self.verticalLayout.addWidget(label)

        scroll_widget.setGeometry(QtCore.QRect(0, 0, 800, 1100))
        scroll.setWidgetResizable(False)
        scroll.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
        scroll.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

        vbar = scroll.verticalScrollBar()
        vbar.setMaximum(scroll_widget.height())
        vbar.setSingleStep(10)
        scroll.setWidget(scroll_widget)

    def scrollEvent(self, event):
        vbar = self.verticalScrollBar()
        val = event.angleDelta().y()

        vbar.setValue(vbar.value() - (val/15)*vbar.singleStep())
        event.accept()

app = QtWidgets.QApplication(sys.argv)
ex = Example()
ex.show()
ex.scroll.verticalScrollBar().valueChanged.connect(ex.scrollEvent)
sys.exit(app.exec_())