使用threading.Timer在Python中按固定间隔截图
我正在用pyGTK写一个简单的图形界面应用程序，目的是定时截取桌面截图。为了安排截图的时间，我使用了threading.Timer这个类，而实际截图则是通过os.system调用scrot来实现的。
当我点击“开始截图”按钮时，会调用GlapseMain.startScreenshots这个方法；而当我点击“停止截图”按钮时，会调用GlapseMain.stopScreenshots这个方法。
问题是，当GTK应用程序在运行时，实际上并没有进行截图，尽管应该是要截图的。当我点击关闭按钮时，它却开始不停地截图。
这是我的代码：
#!/usr/bin/env python
# -*- coding: utf8 -*-
import threading
import os
class GlapseMain:
def __init__(self):
self.outputDir = os.getenv('HOME')
self.quality = 80
self.interval = 10
self.numDigits = 15
self.currentShot = 0
def startScreenshots(self, output, quality, interval):
print 'Starting taking screenshots...'
print 'Output folder: ' + str(output)
print 'Quality: ' + str(quality)
print 'Interval: ' + str(interval)
# Update attributes
self.outputDir = output
self.quality = quality
self.interval = interval
self.currentShot = 0
# Create timer (first screenshot scheduled 1s ahead)
self.timer = threading.Timer(1.0, self._takeScreenshot)
self.timer.start()
def stopScreenshots(self):
print 'Stopped taking screenshots.'
self.timer.cancel()
def _takeScreenshot(self):
# Build scrot command
fileNumber = str(self.currentShot)
fileNumber = fileNumber.zfill(self.numDigits - len(fileNumber))
fileName = 'scr-' + fileNumber + '.jpg'
command = 'scrot -q ' + str(self.quality) + ' ' + self.outputDir + os.sep + fileName
print 'Taking screenshot: ' + command + '...'
os.system(command)
# Schedule next screenshot
self.currentShot = self.currentShot + 1
self.timer = threading.Timer(self.interval, self._takeScreenshot)
self.timer.start()
我的输出看起来像这样：
Starting taking screenshots...
Output folder: /home/david/glapse-screens
Quality: 80.0
Interval: 2.0
Stopped taking screenshots.
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000000.jpg...
Closing gLapse...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000001.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000002.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000003.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000004.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000005.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000006.jpg...
Taking screenshot: scrot -q 80.0 /home/david/glapse-screens/scr-00000000000007.jpg...
希望你能帮我，非常感谢。
编辑：
我改变了方法，现在我使用线程：
def startScreenshots(self, output, quality, interval):
print 'Starting taking screenshots...'
print 'Output folder: ' + str(output)
print 'Quality: ' + str(quality)
print 'Interval: ' + str(interval)
# Update attributes
self.outputDir = output
self.quality = quality
self.interval = interval
self.currentShot = 0
# Start a thread to take screenshots
self.done = False
self.thread = threading.Thread(target=self._takeScreenshot)
self.thread.start()
def stopScreenshots(self):
print 'Stopped taking screenshots.'
self.done = True
self.thread.join()
def _takeScreenshot(self):
# Run until we're done
while not self.done:
# Build scrot command
fileNumber = str(self.currentShot)
fileNumber = fileNumber.zfill(self.numDigits - len(fileNumber))
fileName = 'scr-' + fileNumber + '.jpg'
command = 'scrot -q ' + str(self.quality) + ' ' + self.outputDir + os.sep + fileName
print 'Taking screenshot: ' + command + '...'
os.system(command)
# Schedule next screenshot
print 'Scheduling next screenshot...'
self.currentShot = self.currentShot + 1
time.sleep(self.interval)
它打印了消息，但在我按下停止按钮之前，并没有执行os.system的指令。
1 个回答
4
为了响应：
如果你想在使用gtk的情况下进行多线程处理，你还需要在调用
gtk.gdk.threads_init()
之前先调用它。
让 _takeScreenshot() 使用一个循环，而不是为下一个截图启动一个新线程。你已经有一个工作线程可以用，比如：
你还需要使用线程，而不是定时器。
def _takeScreenshot(self):
while self.notDone:
# take screen shot
# ..
time.sleep(self.interval)
然后在你的取消方法中做类似这样的事情：
def stopScreenshots(self):
self.notDone = False
self.timer.join() # wait for thread to finish