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我正在使用看门狗库来检测何时在特定文件夹中创建了新图像。当看门狗检测到新创建的图像时，我会使用 SimpleCV / OpenCV 启动一些图像处理功能。

但是，这些图片是从 Raspberry Pi 相机拍摄的，并且从下面的错误中，我不相信当它第一次出现在目录中时整个图像都被保存了。（本质上，文件被保存在“片段”或多格式中）。

请注意，当我将图像复制并粘贴到相应的文件夹中时，脚本会成功运行。

问：有没有什么方法可以在整个文件保存后才开始图像处理？

import time
from SimpleCV import Image
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler

class ExampleHandler(FileSystemEventHandler):
    def on_created(self, event):
        image = Image(event.src_path)
        do image processing stuff
        print "Got event for file %s" % event.src_path 

observer = Observer()
event_handler = ExampleHandler() # create event handler
observer.schedule(event_handler, path='/path/to/images') # set observer to use created handler in directory
observer.start()

# sleep until keyboard interrupt, then stop + rejoin the observer
try:
    while True:
        time.sleep(1)
except KeyboardInterrupt:
    observer.stop()

observer.join()

错误转储：

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/api.py", line 241, in run
    self.dispatch_events(self.event_queue, self.timeout)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/api.py", line 408, in dispatch_events
    self._dispatch_event(event, watch)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/api.py", line 403, in _dispatch_event
    handler.dispatch(event)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/events.py", line 361, in dispatch
    _method_map[event_type](event)
  File "picture_classifier_cube.py", line 11, in on_created
    image = Image(event.src_path)
  File "/usr/local/lib/python2.7/dist-packages/SimpleCV/ImageClass.py", line 1073, in __init__
    self._pil = pil.open(self.filename).convert("RGB")
  File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 1980, in open
    raise IOError("cannot identify image file")
IOError: cannot identify image file

编辑在识别新文件后将处理程序更新为休眠几秒钟后，我收到一个不同的错误。

class ExampleHandler(FileSystemEventHandler):
    def on_created(self, event):
        time.sleep(3)
        cans = Image(event.src_path)

错误

IOError: [Errno 2] No such file or directory: '/path/to/images/test.jpg~'

请注意，我正在使用以下 Pi 命令捕获图像：raspistill -o 'test.jpg'

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1 回答 1

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虽然在不修改执行写入的程序的情况下可能无法确定文件是否已完成写入，但您可以监控文件大小：

from os import stat
from time import sleep

def wait_for_write_finish( filename ):
    last_size, size= -1, 0
    while size!=last_size:
        sleep(1)
        last_size, size= size, stat(filename).st_size

您可能希望使用适当的线程来执行此操作

于 2014-05-07T18:36:53.277 回答