python opencv图片imshow怎么实现触摸放大图片功能

要实现触摸放大图片功能，需要用到一些交互式图像显示库，例如`matplotlib`或`pyqtgraph`。以下是使用`matplotlib`实现的示例代码：

import cv2
import matplotlib.pyplot as plt

img = cv2.imread('image.jpg')
plt.imshow(img)

ax = plt.gca()
ax.set_xlim([0, img.shape[1]])
ax.set_ylim([img.shape[0], 0])

def onscroll(event):
    if event.button == 'up':
        scale_factor = 1.1
    elif event.button == 'down':
        scale_factor = 1 / 1.1
    else:
        scale_factor = 1
    
    xdata = event.xdata
    ydata = event.ydata
    xmin, xmax = ax.get_xlim()
    ymin, ymax = ax.get_ylim()
    new_width = (xmax - xmin) * scale_factor
    new_height = (ymax - ymin) * scale_factor
    relx = (xmax - xdata) / (xmax - xmin)
    rely = (ymax - ydata) / (ymax - ymin)
    ax.set_xlim([xdata - new_width * (1 - relx), xdata + new_width * relx])
    ax.set_ylim([ydata - new_height * (1 - rely), ydata + new_height * rely])
    plt.draw()

plt.connect('scroll_event', onscroll)
plt.show()

这个代码会显示一张图片，并且可以通过滚轮缩放和拖动图片。