如何在PyQt5的图像上用笔刷画线

Question

我想在已经打开的图像上画一条线（或画线）。我可以打开图像，但不能在图像上绘画。但是，如果我不打开任何图像，则可以在空白区域上绘制任何想要的图像。

所以，如何用刷子在图像上绘制？对于现在的橡皮擦等，这并不重要。我只想用刷子在图像上做些事情，该图像已经在计算机中打开。

我没有收到任何错误或其他信息。所以我不能专门搜索。

这是我的代码；

from PyQt5.QtWidgets import QMainWindow, QApplication, QMenu, QMenuBar, QAction, QFileDialog, QLabel
from PyQt5.QtGui import QIcon, QImage, QPainter, QPen, QBrush, QPixmap
from PyQt5.QtCore import Qt, QPoint
import sys


class Window(QMainWindow):
    def __init__(self):
        super().__init__()


        title = "Paint Application"
        top = 400
        left = 400
        width = 800
        height = 600

        icon = "icons/pain.png"

        self.setWindowTitle(title)
        self.setGeometry(top, left, width, height)
        self.setWindowIcon(QIcon(icon))

        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)

        self.drawing = False
        self.brushSize = 2
        self.brushColor = Qt.black
        self.lastPoint = QPoint()

        mainMenu = self.menuBar()
        fileMenu = mainMenu.addMenu("File")
        brushSize = mainMenu.addMenu("Brush Size")
        brushColor = mainMenu.addMenu("Brush Color")

        openAction = QAction('Open Image', self)
        openAction.triggered.connect(self.openImage)
        fileMenu.addAction(openAction)

        closeAction = QAction('Exit', self)
        closeAction.triggered.connect(self.close)
        fileMenu.addAction(closeAction)
        self.label = QLabel()
        self.setCentralWidget(self.label)


        saveAction = QAction(QIcon("icons/save.png"), "Save",self)
        saveAction.setShortcut("Ctrl+S")
        fileMenu.addAction(saveAction)
        saveAction.triggered.connect(self.save)

        clearAction = QAction(QIcon("icons/clear.png"), "Clear", self)
        clearAction.setShortcut("Ctrl+C")
        fileMenu.addAction(clearAction)
        clearAction.triggered.connect(self.clear)

        threepxAction = QAction( QIcon("icons/threepx.png"), "3px", self)
        brushSize.addAction(threepxAction)
        threepxAction.triggered.connect(self.threePixel)

        fivepxAction = QAction(QIcon("icons/fivepx.png"), "5px", self)
        brushSize.addAction(fivepxAction)
        fivepxAction.triggered.connect(self.fivePixel)

        sevenpxAction = QAction(QIcon("icons/sevenpx.png"),"7px", self)
        brushSize.addAction(sevenpxAction)
        sevenpxAction.triggered.connect(self.sevenPixel)

        ninepxAction = QAction(QIcon("icons/ninepx.png"), "9px", self)
        brushSize.addAction(ninepxAction)
        ninepxAction.triggered.connect(self.ninePixel)

        blackAction = QAction(QIcon("icons/black.png"), "Black", self)
        blackAction.setShortcut("Ctrl+B")
        brushColor.addAction(blackAction)
        blackAction.triggered.connect(self.blackColor)


        whitekAction = QAction(QIcon("icons/white.png"), "White", self)
        whitekAction.setShortcut("Ctrl+W")
        brushColor.addAction(whitekAction)
        whitekAction.triggered.connect(self.whiteColor)


        redAction = QAction(QIcon("icons/red.png"), "Red", self)
        redAction.setShortcut("Ctrl+R")
        brushColor.addAction(redAction)
        redAction.triggered.connect(self.redColor)

        greenAction = QAction(QIcon("icons/green.png"), "Green", self)
        greenAction.setShortcut("Ctrl+G")
        brushColor.addAction(greenAction)
        greenAction.triggered.connect(self.greenColor)

        yellowAction = QAction(QIcon("icons/yellow.png"), "Yellow", self)
        yellowAction.setShortcut("Ctrl+Y")
        brushColor.addAction(yellowAction)
        yellowAction.triggered.connect(self.yellowColor)


    def openImage(self):
        imagePath, _ = QFileDialog.getOpenFileName()
        pixmap = QPixmap(imagePath)
        self.label.setPixmap(pixmap)
        self.resize(pixmap.size())
        self.adjustSize()

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = True
            self.lastPoint = event.pos()
            #print(self.lastPoint)


    def mouseMoveEvent(self, event):
        if(event.buttons() & Qt.LeftButton) & self.drawing:
            painter = QPainter(self.image)
            painter.setPen(QPen(self.brushColor, self.brushSize, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
            painter.drawLine(self.lastPoint, event.pos())
            self.lastPoint = event.pos()
            self.update()



    def mouseReleaseEvent(self, event):

        if event.button() == Qt.LeftButton:
            self.drawing = False


    def paintEvent(self, event):
        canvasPainter  = QPainter(self)
        canvasPainter.drawImage(self.rect(),self.image, self.image.rect() )





    def save(self):
        filePath, _ = QFileDialog.getSaveFileName(self, "Save Image", "", "PNG(*.png);;JPEG(*.jpg *.jpeg);;All Files(*.*) ")

        if filePath == "":
            return
        self.image.save(filePath)



    def clear(self):
        self.image.fill(Qt.white)
        self.update()


    def threePixel(self):
        self.brushSize = 3

    def fivePixel(self):
        self.brushSize = 5

    def sevenPixel(self):
        self.brushSize = 7

    def ninePixel(self):
        self.brushSize = 9


    def blackColor(self):
        self.brushColor = Qt.black

    def whiteColor(self):
        self.brushColor = Qt.white

    def redColor(self):
        self.brushColor = Qt.red

    def greenColor(self):
        self.brushColor = Qt.green

    def yellowColor(self):
        self.brushColor = Qt.yellow




if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Window()
    window.show()
app.exec()

Answer 1

而不是从文件路径构造QPixmap，而是构造QImage并将其分配给变量self.image。您无需更改任何其他内容，因为paintEvent将绘制由self.image指向的QImage对象。

def openImage(self):
    imagePath, _ = QFileDialog.getOpenFileName()
    self.image = QImage(imagePath)
    self.resize(self.image.size())