QPainter在两个小部件之间画线

Question

我有一个布局，我要在此布局中添加一个按钮（通过单击添加按钮）。

[每次我添加一个按钮时，我都想在上一个按钮和新按钮之间画一条线。每当我添加一个按钮时，都会完成此操作。另外，新按钮具有单击功能，当我单击它时，我将删除此按钮，并且在此按钮和上一个按钮之间画线，并更新布局。

似乎很复杂，但是我看到一些应用程序正在执行此操作。也许他们没有使用与我使用的布局相同的布局。

@@ eyllanesc，帮助安装了此事件，但它更加静态。每次更新布局时，我都需要使其更具动态性。 Pyqt5 draw a line between two widgets。以下是我的一些虚拟试验]

import sys

from PyQt5.QtCore import QEvent
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget


class Drawer:
    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawLine(self.p1, self.p2)


class Example(QWidget, Drawer):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.initUI()

    def initUI(self):
        self.AddButton = QPushButton("Add")
        self.AddButton.clicked.connect(self.addbuttonwithline)

        self.vbox = QVBoxLayout(self)
        self.vbox.addWidget(self.AddButton)

        self.setGeometry(300, 300, 300, 150)
        self.setWindowTitle("Buttons")

    def addbuttonwithline(self):

        # Add buttons
        b = QPushButton('delete')
        self.vbox.addWidget(b)

        # delete the button and it's corresponding line
        b.clicked.connect(self.deletebuttonandlines)

        # Define buttons
        curr_ind = self.vbox.indexOf(b)
        previous_but = self.vbox.itemAt(curr_ind-1).widget()

        # Draw lines
        self.p1, self.p2 = previous_but.pos(), b.pos()

        previous_but.installEventFilter(self)
        b.installEventFilter(self)

    def deletebuttonandlines(self):
        # Delete this button and it's corresponding line and update the layout


    def eventFilter(self, o, e):
        if e.type() == QEvent.Move:
            self.p1 = self.p1
            self.p2 = self.p2
            self.update()
        return super().eventFilter(o, e)


if __name__ == "__main__":

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

Answer 1

逻辑类似：跟踪事件和更改（例如创建和销毁小部件），然后使用信息获取信息以划清界限：

import functools
import sys

from PyQt5.QtCore import QEvent, QLine
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget


class Drawer:
    def __init__(self):
        self._lines = []

    @property
    def lines(self):
        return self._lines

    @lines.setter
    def lines(self, l):
        self._lines = l[:]
        self.update()

    def paintEvent(self, event):
        painter = QPainter(self)
        for line in self.lines:
            painter.drawLine(line)


class Example(QWidget, Drawer):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.initUI()

    def initUI(self):
        self.AddButton = QPushButton("Add")
        self.AddButton.clicked.connect(self.addbuttonwithline)

        self.vbox = QVBoxLayout(self)
        self.vbox.addWidget(self.AddButton)

        self.setGeometry(300, 300, 300, 150)
        self.setWindowTitle("Buttons")

        self.buttons = []

    def addbuttonwithline(self):
        button = QPushButton("delete")
        button.clicked.connect(functools.partial(self.remove_button, button))
        button.installEventFilter(self)
        self.vbox.addWidget(button)
        self.buttons.append(button)
        self.recalculate_position()

    def remove_button(self, button):
        self.buttons.remove(button)
        button.deleteLater()
        self.recalculate_position()

    def recalculate_position(self):
        lines = []
        for last_button, next_button in zip(self.buttons, self.buttons[1:]):
            l = QLine(last_button.pos(), next_button.pos())
            lines.append(l)
        self.lines = lines

    def eventFilter(self, o, e):
        if e.type() == QEvent.Move and o in self.buttons:
            self.recalculate_position()
        return super().eventFilter(o, e)


if __name__ == "__main__":

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