Question

#Importing necessary libraries, mainly the OpenCV, and PyQt libraries
import cv2
import numpy as np
import sys
from PyQt5 import QtCore
from PyQt5 import QtWidgets
from PyQt5 import QtGui
from PyQt5.QtCore import pyqtSignal

class ShowVideo(QtCore.QObject):

    #initiating the built in camera
    camera_port = -1
    camera = cv2.VideoCapture(camera_port)
    VideoSignal = QtCore.pyqtSignal(QtGui.QImage)

    def __init__(self, parent = None):
        super(ShowVideo, self).__init__(parent)

    @QtCore.pyqtSlot()
    def startVideo(self):
        run_video = True

        while run_video:
            ret, image = self.camera.read()

            color_swapped_image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
            height, width, _ = color_swapped_image.shape

            qt_image = QtGui.QImage(color_swapped_image.data,
                                    width, 
                                    height,
                                    color_swapped_image.strides[0],
                                    QtGui.QImage.Format_RGB888)

            pixmap = QtGui.QPixmap(qt_image)
            qt_image = pixmap.scaled(640, 480, QtCore.Qt.KeepAspectRatio)
            qt_image = QtGui.QImage(qt_image)

            self.VideoSignal.emit(qt_image)

    @QtCore.pyqtSlot()
    def makeScreenshot(self):
        #cv2.imwrite("test.jpg", self.image)
        print("Screenshot saved")
        #self.qt_image.save('test.jpg')

class ImageViewer(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super(ImageViewer, self).__init__(parent)
        self.image = QtGui.QImage()
        self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent)



    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        painter.drawImage(0,0, self.image)
        self.image = QtGui.QImage()

    def initUI(self):
        self.setWindowTitle('Test')


    @QtCore.pyqtSlot(QtGui.QImage)
    def setImage(self, image):
        if image.isNull():
            print("viewer dropped frame!")

        self.image = image
        if image.size() != self.size():
            self.setFixedSize(image.size())
        self.update()


if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    thread = QtCore.QThread()
    thread.start()

    vid = ShowVideo()
    vid.moveToThread(thread)
    image_viewer = ImageViewer()
    #image_viewer.resize(200,400)

    vid.VideoSignal.connect(image_viewer.setImage)

    #Button to start the videocapture:

    push_button = QtWidgets.QPushButton('Start')
    push_button.clicked.connect(vid.startVideo)
    push_button2 = QtWidgets.QPushButton('Screenshot')
    push_button2.clicked.connect(vid.makeScreenshot)
    vertical_layout = QtWidgets.QVBoxLayout()

    vertical_layout.addWidget(image_viewer)
    vertical_layout.addWidget(push_button)
    vertical_layout.addWidget(push_button2)

    layout_widget = QtWidgets.QWidget()
    layout_widget.setLayout(vertical_layout)

    main_window = QtWidgets.QMainWindow()
    main_window.setCentralWidget(layout_widget)
    main_window.resize(640,480)
    main_window.show()
    sys.exit(app.exec_())

此代码使用OpenCV和PyQt5在无限循环中显示来自摄像头的视频。但是如何制作截图并且不要停止显示视频。我认为它需要稍微停止循环，让screnshot再次运行循环。

Answer 1

您可以使用cv2.waitKey（），如下所示：

while run_video:
            ret, image = self.camera.read()

            if(cv2.waitKey(10) & 0xFF == ord('s')):
            cv2.imwrite("screenshot.jpg",image)

（我猜这个用术语＆＃34;截图＆＃34;，你的意思是相机框架，而不是整个屏幕的图像。）当你按下＆＃39;在键盘上，它会执行imwrite。请注意，如果您想保存多个图像，则必须更改文件名。上面的代码将覆盖screenshot.jpg以仅保存最新的帧。

如何在显示来自cam的视频时制作屏幕截图？

1 个答案: