selenium无法截屏web元素

Question

我可以用Firefox截屏整个页面。以文件（'2.png'）的形式获取屏幕截图，但当我使用段落截图一个web元素时。屏幕截图（'1.png'），它总是引发这个异常：

selenium.common.exceptions.WebDriverException: Message: Unrecognized command: GET /session/284283fa-53fc-4b33-b329-e6e888dbdcb0/screenshot/{35834cf1-c9c7-4129-99b1-24f30c6b56e6}

Answer 1

Firefox驱动程序中没有实现web元素的屏幕截图。解决方法是从截图中裁剪目标元素：

import StringIO
from selenium import webdriver
from PIL import Image

driver = webdriver.Firefox()
driver.get('http://stackoverflow.com')

# get the logo element
element = driver.find_element_by_id('hlogo')

# crop to the logo from the screenshot
rect = element.rect
points = [rect['x'], rect['y'], rect['x'] + rect['width'], rect['y'] + rect['height']]
with Image.open(StringIO.StringIO(driver.get_screenshot_as_png())) as img :
    with img.crop(points) as imgsub :
        imgsub.save("c:\\temp\\logo.png", 'PNG')

Answer 2

你得到了这个异常，因为你不能只截取selenium中的一个元素的屏幕截图，而没有一些第三方库或你自己的代码来处理这个问题。查看此stackoverflow帖子

它使用一个名为PIL的库来实现：

from selenium import webdriver
from PIL import Image

fox = webdriver.Firefox()
fox.get('https://stackoverflow.com/')

# now that we have the preliminary stuff out of the way time to get that image :D
element = fox.find_element_by_id('hlogo') # find part of the page you want image of
location = element.location
size = element.size
fox.save_screenshot('screenshot.png') # saves screenshot of entire page
fox.quit()

im = Image.open('screenshot.png') # uses PIL library to open image in memory

left = location['x']
top = location['y']
right = location['x'] + size['width']
bottom = location['y'] + size['height']


im = im.crop((left, top, right, bottom)) # defines crop points
im.save('screenshot.png') # saves new cropped image