python - 使用paintEvent 在 QLabel 中绘画

Question

我想在某个标签中绘制一个矩形，我使用 QtDesigner 制作了一个 GUI，它在一个名为“class Ui_MainWindow(QMainWindow):”的类中生成整个 GUI 代码，并且我在窗口中使用了三个选项卡。

我在标签上使用 QMouseEvent 时遇到问题，我找到了使用此代码的解决方案

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt
import sys
import cv2
from PyQt5.QtWidgets import QMainWindow, QWidget, QLabel
from PyQt5.QtGui import QPixmap, QImage

class Ui_MainWindow(QMainWindow):

    def __init__(self):
        # super(Ui_MainWindow, self).__init__ ()
        super().__init__()
        self.count = 0
        self.frame = 0
        self.fileName="0"
        self.imagesTab2 = []
        self.k = 0
        self.i = 1
        self.w = 0
        self.h = 0
        self.coordPt = []
        self.dictListClasses = {
            "face" :[],
            "car" : [] }
        self.dictColorClasses = {
            "face" :(0, 100, 255),
            "car" : (0,255, 0) }


    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(655, 364)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayout = QtWidgets.QVBoxLayout(self.centralwidget)
        self.verticalLayout.setObjectName("verticalLayout")
        self.tabWidget = QtWidgets.QTabWidget(self.centralwidget)
        self.tabWidget.setObjectName("tabWidget")
        self.tab = QtWidgets.QWidget()
        self.tab.setObjectName("tab")
        self.verticalLayout_2 = QtWidgets.QVBoxLayout(self.tab)
        self.verticalLayout_2.setContentsMargins(0, 0, 0, 0)
        self.verticalLayout_2.setObjectName("verticalLayout_2")
        self.horizontalLayout = QtWidgets.QHBoxLayout()
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.pushButton = QtWidgets.QPushButton(self.tab)
        self.pushButton.setObjectName("pushButton")
        self.horizontalLayout.addWidget(self.pushButton)
        self.verticalLayout_2.addLayout(self.horizontalLayout)
        self.label = QtWidgets.QLabel(self.tab)
        self.label.setText("")
        self.label.setObjectName("label")
        self.label.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.label.setFrameShadow(QtWidgets.QFrame.Sunken)
        self.setMouseEventDelegate(self.label)
        self.verticalLayout_2.addWidget(self.label)
        self.verticalLayout_2.setStretch(1, 1)
        self.tabWidget.addTab(self.tab, "")
        self.tab_2 = QtWidgets.QWidget()
        self.tab_2.setObjectName("tab_2")
        self.tabWidget.addTab(self.tab_2, "")
        self.verticalLayout.addWidget(self.tabWidget)
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 655, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Open"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab), _translate("MainWindow", "Tab 1"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab_2), _translate("MainWindow", "Tab 2"))

        self.pushButton.clicked.connect(self.openFileTab2)

    def setMouseEventDelegate (self, setQWidget):
        def subWidgetMousePressEvent(e: QtGui.QMouseEvent):
            if self.imagesTab2:
                if e.button() == Qt.LeftButton:
                    po = int(e.x()*self.w/self.label.width())
                    pa = int(e.y()*self.h/self.label.height())
                    self.coordPt = [(po, pa)]
                    print("coords click = ", self.coordPt)
                    self.begin = e.pos()
                    self.end = e.pos()
                    self.label.update()
                    print("begin 1= ",self.begin, self.end)

        def subWidgetMouseMoveEvent(e: QtGui.QMouseEvent):
            if self.imagesTab2:
                self.end = e.pos()
                self.label.update()

        def subWidgetMouseReleaseEvent(e: QtGui.QMouseEvent):
            if e.button() == Qt.LeftButton:
                if self.imagesTab2:
                    if e.x() >= 0 and e.y() >= 0 and e.x()<self.label.width() and e.y()<self.label.height():
                        po = int(e.x()*self.w/self.label.width())
                        pa = int(e.y()*self.h/self.label.height())
                        self.coordPt.append((po, pa))
                        print("coords release = ", self.coordPt)
                        self.begin = e.pos()
                        self.end = e.pos()
                        self.label.update()
                        print("begin 2= ",self.begin, self.end)
                        self.dictListClasses["car"].append(self.coordPt)
                        print("LL + ", self.dictListClasses)
        setQWidget.mousePressEvent = subWidgetMousePressEvent
        setQWidget.mouseReleaseEvent = subWidgetMouseReleaseEvent
        setQWidget.mouseMoveEvent = subWidgetMouseMoveEvent

    def openFileTab2(self):
        self.imagesTab2, _ = QtWidgets.QFileDialog.getOpenFileNames(None,"Select one or more images to open", "/Images","Images (*.jpg *.jpeg .*bmp .*png);;All Files (*)")
        if self.imagesTab2:
            self.showImageInLabel(self.imagesTab2[0])
            # self.label_9.setText("Image 1")

    def showImageInLabel(self, img):
        pix = QPixmap(img)
        self.w = pix.width()
        self.h = pix.height()
        print("Image resolution = ", '(',self.w,')', '(',self.h,')')
        pix = pix.scaled(self.size(), aspectRatioMode=QtCore.Qt.KeepAspectRatio, ) # To scale image for example and keep its Aspect Ration  
        self.label.setPixmap(pix)
        self.label.setScaledContents(True)


    def nextImageTab2(self):
        if not self.imagesTab2:
            print("No files, please open one or more images")
            return
        if self.i < len(self.imagesTab2):
            path = self.imagesTab2[self.i]
            self.showImageInLabel(path)
            self.i += 1
            print(self.i)
            x = "Image " + str(self.i)
            # self.label_9.setText(x)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

上面的代码是重写三个函数:mousePressEvent、mouseReleaseEvent 和 mouseMoveEvent因为如果我只使用 def mouseMoveEvent (self, event): 例如，它在我的标签上不起作用，我不知道如何将其设置为在某个标签上工作

所以我尝试重写 QPaintEvent 函数，但是如果我使用上面的代码并使用这个 setQWidget.paintEvent = subWidgetPaintEvent 标签就会消失，我只找到一个矩形

任何人都可以帮助我使用我的标签上的事件，就像这段代码一样，谢谢

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import QPainter, QColor, QBrush
from PyQt5 import QtWidgets, QtCore, QtGui

class Labella(QLabel):

    def __init__(self, parent):
        super().__init__(parent=parent)
        self.setStyleSheet('QFrame {background-color:white;}')
        self.resize(300, 300)
        self.begin = QtCore.QPoint()
        self.end = QtCore.QPoint()

    def paintEvent(self, event):
        qp = QtGui.QPainter(self)
        br = QtGui.QBrush(QtGui.QColor(100, 10, 10, 40))  
        qp.setBrush(br)   
        qp.drawRect(QtCore.QRect(self.begin, self.end))       

    def mousePressEvent(self, event):
        self.begin = event.pos()
        self.end = event.pos()
        self.update()
        print("beegin = ", self.begin)
        print("end 1 = ", self.end)

    def mouseMoveEvent(self, event):
        self.end = event.pos()
        self.update()

    def mouseReleaseEvent(self, event):
        self.begin = event.pos()
        self.end = event.pos()
        self.update()

    def drawRectangles(self, qp):    
        qp.setBrush(QColor(255, 0, 0, 100))
        qp.save() # save the QPainter config

        qp.drawRect(10, 15, 20, 20)

        qp.setBrush(QColor(0, 0, 255, 100))
        qp.drawRect(50, 15, 20, 20)

        qp.restore() # restore the QPainter config            
        qp.drawRect(100, 15, 20, 20)

class Example(QWidget):

    def __init__(self):
        super().__init__()

    lb = Labella(self)

    self.setGeometry(300, 300, 350, 300)
    self.setWindowTitle('Colours')
    self.show()

if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

Answer 1

解决方案是提升 Labella 在 Qt Designer 中使用，为此您必须首先创建文件 labella.py。

labella.py

from PyQt5 import QtCore, QtGui, QtWidgets

class Labella(QtWidgets.QLabel):
    def __init__(self, parent):
        super().__init__(parent=parent)
        self.setStyleSheet('QFrame {background-color:white;}')
        self.resize(300, 300)
        self.begin = QtCore.QPoint()
        self.end = QtCore.QPoint()

    def paintEvent(self, event):
        super().paintEvent(event)
        qp = QtGui.QPainter(self)
        br = QtGui.QBrush(QtGui.QColor(100, 10, 10, 40))  
        qp.setBrush(br)   
        qp.drawRect(QtCore.QRect(self.begin, self.end))       

    def mousePressEvent(self, event):
        self.begin = event.pos()
        self.end = event.pos()
        self.update()
        print("beegin = ", self.begin)
        print("end 1 = ", self.end)

    def mouseMoveEvent(self, event):
        self.end = event.pos()
        self.update()

    def drawRectangles(self, qp):    
        qp.setBrush(QColor(255, 0, 0, 100))
        qp.save() # save the QPainter config
        qp.drawRect(10, 15, 20, 20)
        qp.setBrush(QColor(0, 0, 255, 100))
        qp.drawRect(50, 15, 20, 20)
        qp.restore() # restore the QPainter config            
        qp.drawRect(100, 15, 20, 20)

然后我们将 labella.py 和将调用 mainwindow.ui 的 .ui 放在同一文件夹中

.
├── labella.py
└── mainwindow.ui

您可以通过获取以下内容来打开 .ui 文件:

右键单击QLabel并选择选项:升级到...

填写如下图所示的字段，然后按添加按钮，然后按推广按钮:

最后在pyuic5的帮助下再次生成.py:

pyuic5 mainwindow.ui -o mainwindow.py -x