import time
import cv2
import numpy
class CaptureManager(object):
def __init__(self, capture, previewWindowManager=None, shouldMirrorPreview=False):
self.previewWindowManager = previewWindowManager
self.shouldMirrorPreview = shouldMirrorPreview
self._capture = capture
self._channel = 0
self._enteredFrame = False
self._frame = None
self._imageFilename = None
self._videoFilename = None
self._videoEncoding = None
self._videoWriter = None
self._startTime = None
self._framesElapsed = long(0)
self._fpsEstimate = None
@property
def channel(self):
return self._channel
@channel.setter
def channel(self, value):
if self._channel != value:
self._channel = value
self._frame = None
@property
def frame(self):
if self._enteredFrame and self._frame is None:
_, self._frame = self._capture.retrieve()
return self._frame
@property
def isWritingImage(self):
return self._imageFilename is not None
@property
def isWritingVideo(self):
return self._videoFilename is not None
def enterFrame(self):
"""捕获下一帧，如果有的话"""
assert not self._enteredFrame, \
'previous enterFrame() had no matching exitFrame()'
if self._capture is not None:
self._enteredFrame = self._capture.grab()
def exitFrame(self):
"""绘制窗口. 写入文件. 释放."""
if self.frame is None:
self._enteredFrame = False
return
if self._framesElapsed == 0:
self._startTime = time.time()
else:
timeElapsed = time.time() - self._startTime
self._fpsEstimate = self._framesElapsed / timeElapsed
self._framesElapsed += 1
if self.previewWindowManager is not None:
if self.shouldMirrorPreview:
mirroredFrame = numpy.fliplr(self._frame).copy()
self.previewWindowManager.show(mirroredFrame)
else:
self.previewWindowManager.show(self._frame)
if self.isWritingImage:
cv2.imwrite(self._imageFilename, self._frame)
self._imageFilename = None
self._writeVideoFrame()
self._frame = None
self._enteredFrame = False
def writeImage(self, filename):
"""写入一帧到图像"""
self._imageFilename = filename
def startWritingVideo(self, filename, encoding=cv2.VideoWriter_fourcc('I', '4', '2', '0')):
"""开始准备写入视频"""
self._videoFilename = filename
self._videoEncoding = encoding
def stopWritingVideo(self):
"""停止写入视频"""
self._videoFilename = None
self._videoEncoding = None
self._videoWriter = None
def _writeVideoFrame(self):
if not self.isWritingVideo:
return
if self._videoWriter is None:
fps = self._capture.get(cv2.CAP_PROP_FPS)
if fps == 0.0:
if self._framesElapsed < 20:
return
else:
fps = self._fpsEstimate
size = (int(self._capture.get(cv2.CAP_PROP_FRAME_WIDTH)), int(self._capture.get(cv2.CAP_PROP_FRAME_HEIGHT)))
self._videoWriter = cv2.VideoWriter(self._videoFilename, self._videoEncoding, fps, size)
self._videoWriter.write(self._frame)
class WindowManager(object):
def __init__(self, windowName, keypressCallback=None):
self.keypressCallback = keypressCallback
self._windowName = windowName
self._isWindowCreated = False
@property
def isWindowCreated(self):
return self._isWindowCreated
def createWindow(self):
cv2.namedWindow(self._windowName)
self._isWindowCreated = True
def show(self, frame):
cv2.imshow(self._windowName, frame)
def destroyWindow(self):
cv2.destroyWindow(self._windowName)
self._isWindowCreated = False
def processEvents(self):
keycode = cv2.waitKey(1)
if self.keypressCallback is not None and keycode != -1:
keycode &= 0xFF
self.keypressCallback(keycode)
class Cameo(object):
def __init__(self):
self._windowManager = WindowManager('Cameo', self.onKeypress)
self._captureManager = CaptureManager(cv2.VideoCapture(0), self._windowManager, True)
def run(self):
"""开始循环"""
self._windowManager.createWindow()
while self._windowManager.isWindowCreated:
self._captureManager.enterFrame()
frame = self._captureManager.frame
self._captureManager.exitFrame()
self._windowManager.processEvents()
def onKeypress(self, keycode):
"""
处理案件
space -> 截屏
tab -> 开始/停止录像
escape -> 退出
"""
if keycode == 32:
self._captureManager.writeImage('screenshot.png')
elif keycode == 9:
if not self._captureManager.isWritingVideo:
self._captureManager.startWritingVideo('screencast.avi')
else:
self._captureManager.stopWritingVideo()
elif keycode == 27:
self._windowManager.destroyWindow()
if __name__ == "__main__":
Cameo().run()
