Although I choose the same camera frame size and widget size, white spaces appear around the window.

How can I remove these whites?

I never understood why these white parts were appearing.

Although I choose the same camera frame size and widget size, white spaces appear around the window.

How can I remove these whites?

I never understood why these white parts were appearing.

'''

class VideoThread(QThread):
    change_pixmap_signal = pyqtSignal(np.ndarray)

    def __init__(self):
        super().__init__()
        self._run_flag = True

    def run(self):
        # capture from analog camera
        cap = cv2.VideoCapture(0)
        cap.set(3,720)
        cap.set(4,576)
        while self._run_flag:
            now1=time.time()
            ret, cv_img = cap.read()
        if ret:
            cv_img = cv2.resize(cv_img, (1024, 768))
            self.change_pixmap_signal.emit(cv_img)
            now2=time.time()
    cap.release()

    def stop(self):
        #stop capture
        self._run_flag = False
        self.wait()


class App(QWidget):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("window")
        self.disply_width = 1024
        self.display_height = 768
        # create the label that holds the image
        self.image_label.resize(self.disply_width, self.display_height)

        # create a vertical box layout and add the two labels
        vbox = QVBoxLayout()
        vbox.addWidget(self.image_label)
        #vbox.addWidget(self.textLabel)
        # set the vbox layout as the widgets layout
        self.setLayout(vbox)

        # create the video capture thread
        self.thread = VideoThread()
        # connect its signal to the update_image slot
        self.thread.change_pixmap_signal.connect(self.update_image)
        # start the thread
        self.thread.start()

    def closeEvent(self, event):
        self.thread.stop()
        event.accept()

    @pyqtSlot(np.ndarray)
    def update_image(self, cv_img):
        """Updates the image_label with a new opencv image"""
        qt_img = self.convert_cv_qt(cv_img)
        self.image_label.setPixmap(qt_img)

    def convert_cv_qt(self, cv_img):
        """Convert from an opencv image to QPixmap"""
        rgb_image = cv2.cvtColor(cv_img, cv2.COLOR_BGR2RGB)
        h, w, ch = rgb_image.shape
        bytes_per_line = ch * w
        convert_to_Qt_format = QtGui.QImage(rgb_image.data, w, h, bytes_per_line, QtGui.QImage.Format_RGB888)
        p = convert_to_Qt_format.scaled(self.disply_width, self.display_height, Qt.KeepAspectRatio)
        return QPixmap.fromImage(p)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    a = App()
    a.show()
    #a.showFullScreen()
    sys.exit(app.exec_())

'''

CodePudding user response：

Use vbox.setContentsMargins(0, 0, 0, 0); to get rid of the white margins.

Plus there are many many more bugs in your code. For example you should not resize the image label self.image_label.resize(self.disply_width, self.display_height) (I guess this should crash, since you have not created the label yet... but I guess you did not show all your code). You should resize the whole window instead, i.e. self.resize(self.disply_width, self.display_height). Well, it seems you have no understanding how layouts work. But this my answer is not intended to teach you, I am only trying to answer your question.