[C++知识库]PyQT5 实现滑动鼠标滚轮进行图片的缩放

?ImageBox是图像绘制类，主要进行图像绘制。

# -*- coding: utf-8 -*-

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtGui import QImageReader
from PyQt5.QtWidgets import QWidget, QApplication, QVBoxLayout, QHBoxLayout, QPushButton, QLabel, QFileDialog, QFrame
from PyQt5.Qt import QPixmap, QPoint, Qt, QPainter, QIcon
from PyQt5.QtCore import QSize


class ImageBox(QWidget):
    def __init__(self):
        super(ImageBox, self).__init__()
        self.img = None
        self.scaled_img = None
        self.point = QPoint(0, 0)
        self.start_pos = None
        self.end_pos = None
        self.left_click = False
        self.scale = 1

    def init_ui(self):
        self.setWindowTitle("ImageBox")

    def set_image(self, img_path):
        """
        open image file
        :param img_path: image file path
        :return:
        """
        # img = QImageReader(img_path)
        # img.setScaledSize(QSize(self.size().width(), self.size().height()))
        # img = img.read()
        self.img = QPixmap(img_path)
        self.scaled_img = self.img
        self.update()

    def paintEvent(self, e):
        """
        receive paint events
        :param e: QPaintEvent
        :return:
        """
        if self.scaled_img:
            painter = QPainter()
            painter.begin(self)
            painter.scale(self.scale, self.scale)
            painter.drawPixmap(self.point, self.scaled_img)
            painter.end()

    def wheelEvent(self, event):
        angle = event.angleDelta() / 8  # 返回QPoint对象，为滚轮转过的数值，单位为1/8度
        angleY = angle.y()
        # 获取当前鼠标相对于view的位置
        if angleY > 0:
            self.scale *= 1.1
        else:  # 滚轮下滚
            self.scale *= 0.9
        self.adjustSize()
        self.update()


    def mouseMoveEvent(self, e):
        """
        mouse move events for the widget
        :param e: QMouseEvent
        :return:
        """
        if self.left_click:
            self.end_pos = e.pos() - self.start_pos
            self.point = self.point + self.end_pos
            self.start_pos = e.pos()
            self.repaint()

    def mousePressEvent(self, e):
        """
        mouse press events for the widget
        :param e: QMouseEvent
        :return:
        """
        if e.button() == Qt.LeftButton:
            self.left_click = True
            self.start_pos = e.pos()

    def mouseReleaseEvent(self, e):
        """
        mouse release events for the widget
        :param e: QMouseEvent
        :return:
        """
        if e.button() == Qt.LeftButton:
            self.left_click = False

class Ui_Form(QWidget):
    def __init__(self,path):
        super(Ui_Form,self).__init__()
        self.setupUi()

    def setupUi(self):
       
        self.scrollArea = QtWidgets.QScrollArea()
        self.scrollArea.setGeometry(QtCore.QRect(240, 50, 719, 309))
        self.scrollArea.setWidgetResizable(True)
        self.scrollArea.setObjectName("scrollArea")
        self.scrollAreaWidgetContents = QtWidgets.QWidget()
        # 定义一个总布局
        self.gridLayout1 = QtWidgets.QVBoxLayout()
        self.scrollAreaWidgetContents.setLayout(self.gridLayout1)

        # self.box是绘图类
        self.box = ImageBox()
        self.scrollAreaWidgetContents.setGeometry(QtCore.QRect(0, 0, self.box.width(), self.box.height()))
        self.scrollAreaWidgetContents.setMinimumSize(QtCore.QSize(719, 309))
        self.scrollAreaWidgetContents.setObjectName("scrollAreaWidgetContents")
        # 子布局
        self.gridLayout = QtWidgets.QGridLayout()
        self.gridLayout.setObjectName("gridLayout")
        # 将绘图类添加进子布局
        self.gridLayout.addWidget(self.box, 0, 0, 1, 1)
        self.scrollArea.setWidget(self.scrollAreaWidgetContents)
        # 打开文件夹按钮，选择要缩放的图片
        self.open_file = QtWidgets.QPushButton('选择图片')
        self.open_file.setGeometry(QtCore.QRect(30, 100, 81, 41))
        self.open_file.setObjectName("open_file")
        self.open_file.clicked.connect(self.open_image)
        # 将按钮加入子布局
        self.gridLayout.addWidget(self.open_file)
        # 将子布局加入总布局
        self.gridLayout1.addLayout(self.gridLayout)
        self.setMinimumSize(500,500)
        # 将总布局设置为当前布局文件
        self.setLayout(self.gridLayout1)



    def open_image(self):
        """
        select image file and open it
        :return:
        """
        # img_name, _ = QFileDialog.getOpenFileName(self, "打开图片", "", "All Files(*);;*.jpg;;*.png")
        img_name, _ = QFileDialog.getOpenFileName(None, "Open Image File","","All Files(*);;*.jpg;;*.png;;*.jpeg")
        # img_name = "icons/Nest_17.png"
       
        # print(img_name)
        img = QPixmap(img_name)
        # print(img.width(),"+",img.height())
        self.scrollAreaWidgetContents.setGeometry(QtCore.QRect(0, 0, img.width(), img.height()))
        self.box.set_image(img_name)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    # 外部布局调用
    m_ui = QFrame()
    m_h_box = QtWidgets.QHBoxLayout()
    m_ui.setLayout(m_h_box)

    ui = Ui_Form()
    ui.setupUi()
    # 通过addWidget()方法
    m_h_box.addWidget(ui)
    m_ui.show()

    sys.exit(app.exec_())

参考了，pyqt5实现图片显示、图片放大/缩小（通过滚轮）、图片移动（鼠标拖动）_小郁同学-CSDN博客