在 PyQt5 中绘制图像顶部跟踪鼠标 [英] Drawing on top of image in PyQt5 tracing the mouse

问题描述

我是 PyQt5 的新手.我正在尝试在跟踪我的鼠标的已加载图像线的顶部绘制，即按下鼠标将导致绘制鼠标移动到的任何内容，同时鼠标仍然按下，并在我们释放鼠标时停止.

我看到了

I'm new to PyQt5. I'm trying to draw on top of a loaded image lines that are tracing my mouse, i.e. pressing the mouse will result in drawing whatever your mouse moves to, while the mouse is still pressed, and stops when we release the mouse.

I saw This answer and it was very helpful, but I'm trying to do something a bit more complicated.

I think I'm messing up with the events.

What I wrote (which doesn't work):

import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtWidgets import QMainWindow, QApplication, QLabel
from PyQt5.QtGui import QPixmap, QPainter, QPen


class Menu(QMainWindow):

    def __init__(self):
        super().__init__()
        self.drawing = False
        self.lastPoint = QPoint()
        self.image = QPixmap("picture.png")
        self.setGeometry(100, 100, 500, 300)
        self.resize(self.image.width(), self.image.height())
        self.label = QLabel(self)
        self.show()

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawPixmap(self.rect(), self.image)
        pen = QPen(Qt.red, 3)
        painter.setPen(pen)
        painter.drawLine(self.lastPoint, event.pos())

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

    def mouseMoveEvent(self, event):
        if event.buttons() and Qt.LeftButton and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(QPen(Qt.red, 3, Qt.SolidLine))
            self.lastPoint = event.pos()
            self.update()

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


if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainMenu = Menu()
    sys.exit(app.exec_())

解决方案

You want to use drawLine in mouseMoveEvent. When you move your mouse, it will invoke mouseMoveEvent which will draw a line from the last position, and then it will invoke by itself the paintEvent.

Try this:

import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtWidgets import QMainWindow, QApplication
from PyQt5.QtGui import QPixmap, QPainter, QPen


class Menu(QMainWindow):

    def __init__(self):
        super().__init__()
        self.drawing = False
        self.lastPoint = QPoint()
        self.image = QPixmap("picture.png")
        self.setGeometry(100, 100, 500, 300)
        self.resize(self.image.width(), self.image.height())
        self.show()

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawPixmap(self.rect(), self.image)

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

    def mouseMoveEvent(self, event):
        if event.buttons() and Qt.LeftButton and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(QPen(Qt.red, 3, Qt.SolidLine))
            painter.drawLine(self.lastPoint, event.pos())
            self.lastPoint = event.pos()
            self.update()

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


if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainMenu = Menu()
    sys.exit(app.exec_())

这篇关于在 PyQt5 中绘制图像顶部跟踪鼠标的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！