如何正确更新 QLabel 图像？ [复制]

Question

我有一个名为 ImageLabel 的自定义 QLabel 类来显示图像和视频流。我想用setPixmap() 方法更新图像，但它不能正确更新图像。

注意：StreamThread 方法与视频流有关，我暂时不使用它来更新图像。

这是扭曲的图像：

主类：

import sys

from PyQt5.QtCore import Qt, pyqtSlot
from PyQt5.QtGui import QImage, QPixmap
from PyQt5.QtWidgets import QApplication, QVBoxLayout, QWidget, QPushButton, QHBoxLayout


from ImageLabel import ImageLabel
from Stream_Thread import Stream_Thread

import cv2

class MainWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.init_UI()


    def init_UI(self):
        self.setFixedSize(690, 530)
        self.image_lbl = ImageLabel()

        # start the video stream of selected camera
        th = Stream_Thread()
        th.set_index(1)
        th.changePixmap.connect(self.setImage, Qt.QueuedConnection)
        th.start()


        btn_cnt = QPushButton("Continue")
        btn_pa = QPushButton("Pause")

        hbox = QHBoxLayout()
        hbox.addWidget(btn_cnt)
        hbox.addWidget(btn_pa)

        vbox = QVBoxLayout()
        vbox.addWidget(self.image_lbl)
        vbox.addLayout(hbox)

        self.setLayout(vbox)

        btn_pa.clicked.connect(lambda: self.btn_pa_clicked(th))

        self.show()


    @pyqtSlot(QImage)
    def setImage(self, image):
       self.image_lbl.pixmap = QPixmap.fromImage(image).scaled(720, 540)
       self.image_lbl.setPixmap(QPixmap.fromImage(image).scaled(720, 540))

    def btn_pa_clicked(self, th):
        th.terminate()                                                    # terminates the video stream

        image = cv2.imread("img/49.jpg", cv2.COLOR_BGR2RGB)  # self.image_lbl.pixmap
        # image = image.toImage()
        if image is not None:
            (h, w, c) = image.shape
            qimage = QImage(image.data, h, w, 3 * h, QImage.Format_RGB888)
            self.image_lbl.pixmap = QPixmap.fromImage(qimage)
            #self.image_lbl.setPixmap(QPixmap.fromImage(qimage))
            self.image_lbl.repaint()


def main():
    app = QApplication(sys.argv)
    main_form = MainWindow()
    sys.exit(app.exec_())



if __name__ == '__main__':
    main()

StreamThread 类：

import cv2
from PyQt5.QtCore import QThread, pyqtSignal, Qt
from PyQt5.QtGui import QImage

#https://stackoverflow.com/a/44404713/13080899
class Stream_Thread(QThread):
    changePixmap = pyqtSignal(QImage)

    def __init__(self):
        super(Stream_Thread, self).__init__()
        self.ref = False        #refresh flag

    def set_index(self, index = 0):
        self.index = int(index)

    def refresh(self):
        self.ref = True
        self.capt.open(self.index)


    def run(self):
        self.capt = cv2.VideoCapture(self.index, cv2.CAP_DSHOW)

        while(True):
            ret, frame = self.capt.read()

            if ret:
                rbgImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
                h, w, ch = rbgImage.shape
                bytesPerLine = ch*w
                convertToQtFormat = QImage(rbgImage.data, w, h, bytesPerLine, QImage.Format_RGB888)
                p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
                self.changePixmap.emit(p)

ImageLabel 类：

from PyQt5 import QtGui, QtCore
from PyQt5.QtCore import Qt, QSize, pyqtSignal, QObject, QPoint, pyqtSlot
from PyQt5.QtWidgets import QLabel

class Communicate(QObject):
    cor_update = pyqtSignal()
    cor_curr = pyqtSignal()

class ImageLabel(QLabel):
    def __init__(self, width=720, height=540):
        super(ImageLabel, self).__init__()
        self.setMouseTracking(True)
        self.pixmap = QtGui.QPixmap("img/im.jpg")

        #### initialize coordinates ####
        self.x1 = 0
        self.y1 = 0

        self.x_curr = 0
        self.y_curr = 0

        self.x2 = 0
        self.y2 = 0

        ##### enable state to allow user for drawing
        self.enable_labelling = False

        ##### enable state to track coordinates for drawing
        self.enable_cor = False

        ################################
        self.source = Communicate()

    def paintEvent(self, event):
        qp = QtGui.QPainter(self)
        qp.drawPixmap(self.rect(), self.pixmap)
        if self.enable_labelling == True:
            self.paintRect(event, qp)
            qp.end()

    def paintRect(self, event, qp):
        br = QtGui.QBrush(QtGui.QColor(50, 255, 255, 40))
        qp.setBrush(br)

        if self.enable_cor == True:
            qp.drawRect(QtCore.QRect(QPoint(self.x1, self.y1), QSize(self.x_curr - self.x1, self.y_curr - self.y1)))
        else:
            qp.drawRect(QtCore.QRect(QPoint(self.x1, self.y1), QSize(self.x2 - self.x1, self.y2 - self.y1)))

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton and self.enable_labelling == True:
            self.x1 = event.x()
            self.y1 = event.y()

            self.enable_cor = True

            self.source.cor_update.emit()

    def mouseMoveEvent(self, event):
        self.x_curr = event.x()
        self.y_curr = event.y()

        self.source.cor_curr.emit()

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton and self.enable_labelling == True:
            self.x2 = event.x()
            self.y2 = event.y()

            self.source.cor_update.emit()

            self.enable_cor = False

Answer 1

不是通过 Imread 打开图像并将其转换为 QImage，而是通过 QImage 打开它并转换应该可以解决您的问题的格式。用途：

image = QImage("img/49.jpg");
image = image.convertToFormat(QImage.Format_RGB888);

这是伪代码，未经测试，可能需要修改。