pyqt上显示图片并可以进行放大缩小，画图

要在PyQt中显示图片并可以进行放大缩小，可以使用QLabel和QPixmap类。以下是一个示例代码：

from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout
from PyQt5.QtGui import QPixmap
from PyQt5.QtCore import Qt

class ImageViewer(QWidget):
    def __init__(self):
        super().__init__()

        self.setWindowTitle('Image Viewer')
        self.setGeometry(100, 100, 800, 600)

        self.image_label = QLabel(self)
        self.image_label.setAlignment(Qt.AlignCenter)

        self.layout = QVBoxLayout(self)
        self.layout.addWidget(self.image_label)

        self.image_path = 'image.jpg'  # 图片路径
        self.show_image()

    def show_image(self):
        pixmap = QPixmap(self.image_path)
        self.image_label.setPixmap(pixmap)

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            self.image_label.resize(self.image_label.width() * 1.1, self.image_label.height() * 1.1)
        else:
            self.image_label.resize(self.image_label.width() * 0.9, self.image_label.height() * 0.9)


if __name__ == '__main__':
    app = QApplication([])
    iv = ImageViewer()
    iv.show()
    app.exec_()

该示例代码创建了一个名为ImageViewer的QWidget窗口，其中包含一个QLabel标签，用于显示一张图片。该窗口还实现了wheelEvent方法，以便捕获鼠标滚轮事件并缩放图片。要在该窗口中绘制图形，可以使用QPainter类。以下是一个示例代码：

from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QVBoxLayout
from PyQt5.QtGui import QPixmap, QPainter, QPen
from PyQt5.QtCore import Qt, QPoint

class Drawing(QWidget):
    def __init__(self):
        super().__init__()

        self.setWindowTitle('Drawing')
        self.setGeometry(100, 100, 800, 600)
        self.setMouseTracking(True)

        self.image_label = QLabel(self)
        self.image_label.setAlignment(Qt.AlignCenter)

        self.layout = QVBoxLayout(self)
        self.layout.addWidget(self.image_label)

        self.image_path = 'image.jpg'  # 图片路径
        self.show_image()

        self.drawing = False
        self.last_point = QPoint()

    def show_image(self):
        pixmap = QPixmap(self.image_path)
        self.image_label.setPixmap(pixmap)

    def paintEvent(self, event):
        if self.drawing:
            painter = QPainter(self)
            painter.setPen(QPen(Qt.red, 3))
            painter.drawLine(self.last_point, self.current_point)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = True
            self.last_point = self.current_point = event.pos()

    def mouseMoveEvent(self, event):
        if self.drawing:
            self.current_point = event.pos()
            self.update()

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            self.image_label.resize(self.image_label.width() * 1.1, self.image_label.height() * 1.1)
        else:
            self.image_label.resize(self.image_label.width() * 0.9, self.image_label.height() * 0.9)


if __name__ == '__main__':
    app = QApplication([])
    dw = Drawing()
    dw.show()
    app.exec_()

该示例代码创建了一个名为Drawing的QWidget窗口，其中可以在图片上绘制线条。该窗口还实现了mousePressEvent、mouseMoveEvent和mouseReleaseEvent方法，以便捕获鼠标事件并绘制线条。要在该窗口中绘制其他形状，可以使用QPainter类的其他方法。