QPainter不画

Question

我试图用变量QPainter绘制一些线，但它没有做到这一点。当我试图画任何其他东西，但是我用手传递数字时，一切都进展顺利。这是我的密码：

import sys, os
from math import pi
from PyQt5.QtWidgets import (QApplication, QWidget, QPushButton, QMenuBar, QMenu, QAction, QHBoxLayout, QFileDialog)
from PyQt5.QtGui import (QPainter, QPen)
from PyQt5.QtCore import (Qt, QPoint, QLineF)

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

        self.coords, self.graph, self.used, self.tin, self.fup, self.con_points = [], [], [], [], [], []
        self.num_of_peaks, self.circle_size, self.timer = 0, 40, 0
        self.algo_starts, self.from_file = False, False
        self.graph_config, self.graph_new = None, None

        self.lines = []

        self.setGeometry(300, 300, 1000, 500)
        self.move(QApplication.desktop().screen().rect().center()-self.rect().center())
        self.setWindowTitle("con point")

        self.menubar = QMenuBar(self)
        self.filemenu = self.menubar.addMenu("File")
        self.newfile = self.filemenu.addAction("New")
        self.openfile = self.filemenu.addAction("Open")
        self.savefile = self.filemenu.addAction("Save")
        self.exitfile = self.filemenu.addAction("Exit")

        self.filemenu.triggered[QAction].connect(self.ProcessTrigger)

        self.startalgobtn = QPushButton("Start", self)
        self.startalgobtn.setGeometry(self.width()-self.startalgobtn.width(), self.menubar.height(),self.startalgobtn.width(), self.startalgobtn.height())
        self.startalgobtn.setVisible(False)

        self.exitbtn = QPushButton("Exit", self)
        self.exitbtn.setGeometry(self.width()-self.startalgobtn.width(), self.menubar.height() + self.exitbtn.height(),self.startalgobtn.width(),
                                 self.startalgobtn.height())
        self.exitbtn.setVisible(False)
        self.exitbtn.clicked.connect(self.Exit)

        self.show()

    def ProcessTrigger(self, q):
        if q == self.newfile: self.NewFile()
        if q == self.openfile: self.OpenFile()
        if q == self.savefile: self.SaveFile()
        if q == self.exitfile: self.Exit()

    def paintEvent(self, a0):
        self.paint_teritory = QPainter(self)
        self.paint_teritory.setRenderHint(QPainter.Antialiasing)
        self.paint_teritory.setBackground(Qt.white)
        self.paint_teritory.setBrush(Qt.black)
        self.paint_teritory.setPen(QPen(Qt.black, 2, Qt.SolidLine))
        self.paint_teritory.drawEllipse(40, 40, 40, 40)
        self.paint_teritory.drawLines(self.lines)

        self.paint_teritory.end()

    def NewFile(self):
        return

    def OpenFile(self):
        self.from_file = True
        self.graph_config = QFileDialog.getOpenFileName(self, "Open File", os.getcwd(), "Text Files (*.txt)")[0]
        self.ReadGraph()

    def SaveFile(self):
        return

    def Exit(self): QApplication.instance().quit()

    def ReadGraph(self):
        if self.from_file:
            with open(self.graph_config) as f: self.graph_config = f.readlines()

            self.num_of_peaks = int(self.graph_config[0])
            self.graph = [[] for x in range(self.num_of_peaks)]

            i = 1
            while self.graph_config[i] != "COORDS\n":
                line = self.graph_config[i].split()
                if len(line) == 1: self.graph[int(line[0])-1] = []
                else: self.graph[int(line[0])-1] = sorted(list(map(int, line[1::])))
                i += 1

            i += 1
            for x in range(i, len(self.graph_config)):
                self.coords.append(list(map(int, self.graph_config[i].split())))

        for i in self.graph:
            for j in i:
                self.lines.append(
                    QLineF(QPoint(self.coords[self.graph.index(i)][0], self.coords[self.graph.index(i)][1]),
                           QPoint(self.coords[j - 1][0], self.coords[j - 1][1])))
        self.conf_yes = True

        self.startalgobtn.setVisible(True)
        self.exitbtn.setVisible(True)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    con_point_app = MainWindow()
    sys.exit(app.exec_())

所以，正如我所说的，当我试图用self.lines绘图时，什么都不会发生，但是当我用self.paint_teritory.drawEllipse(40, 40, 40, 40)画一个圆圈时，它实际上就出现了。

下面是我用来测试的文件：hoClfllYLvFXB78Cjxyh/view?usp=sharing

这就是如何为这个程序制作一个程序：https://drive.google.com/open?id=1EPxlxUPxH3oWaYJdi9N3RVtC7WPokOCU

Answer 1

问题是，您生成的行的起始点和结束点是相同的，因此这是无效的，PyQt将创建一个空QLine。

此外，绘制线条也很费劲，在本例中，最可取的方法是使用QPainterPath，如下所示：

import sys, os
from math import pi
from PyQt5.QtWidgets import (QApplication, QWidget, QPushButton, QMenuBar, QMenu, QAction, QHBoxLayout, QFileDialog)
from PyQt5.QtGui import (QPainter, QPen, QPainterPath)
from PyQt5.QtCore import (Qt, QPointF, QLineF)

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

        self.algo_starts, self.from_file = False, False
        self.graph_config, self.graph_new = None, None

        self.paths = []

        self.setGeometry(300, 300, 1000, 500)
        self.move(QApplication.desktop().screen().rect().center()-self.rect().center())
        self.setWindowTitle("con point")

        self.menubar = QMenuBar(self)
        self.filemenu = self.menubar.addMenu("File")
        self.newfile = self.filemenu.addAction("New")
        self.openfile = self.filemenu.addAction("Open")
        self.savefile = self.filemenu.addAction("Save")
        self.exitfile = self.filemenu.addAction("Exit")

        self.filemenu.triggered[QAction].connect(self.ProcessTrigger)

        self.startalgobtn = QPushButton("Start", self)
        self.startalgobtn.setGeometry(self.width()-self.startalgobtn.width(), self.menubar.height(),self.startalgobtn.width(), self.startalgobtn.height())
        self.startalgobtn.setVisible(False)

        self.exitbtn = QPushButton("Exit", self)
        self.exitbtn.setGeometry(self.width()-self.startalgobtn.width(), self.menubar.height() + self.exitbtn.height(),self.startalgobtn.width(),
                                 self.startalgobtn.height())
        self.exitbtn.setVisible(False)
        self.exitbtn.clicked.connect(self.Exit)

        self.show()

    def ProcessTrigger(self, q):
        if q == self.newfile: self.NewFile()
        if q == self.openfile: self.OpenFile()
        if q == self.savefile: self.SaveFile()
        if q == self.exitfile: self.Exit()

    def paintEvent(self, a0):
        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)
        painter.setBackground(Qt.white)
        painter.setBrush(Qt.black)
        painter.setPen(QPen(Qt.black, 2, Qt.SolidLine))
        painter.drawEllipse(40, 40, 40, 40)
        painter.setBrush(Qt.NoBrush)
        for path in self.paths:
            painter.drawPath(path)

    def NewFile(self):
        return

    def OpenFile(self):
        self.from_file = True
        self.graph_config = QFileDialog.getOpenFileName(self, "Open File", os.getcwd(), "Text Files (*.txt)")[0]
        self.ReadGraph()

    def SaveFile(self):
        return

    def Exit(self): QApplication.instance().quit()

    def ReadGraph(self):
        if self.from_file:
            with open(self.graph_config) as f: data = f.readlines()
            num_of_peaks, *info = data
            ix = info.index("COORDS\n")
            vertices_raw = info[:ix]
            coords_raw = info[ix+1:]
            vertices = [list(map(int, vertice.split())) for vertice in vertices_raw]
            coords = [list(map(int, coord.split())) for coord in coords_raw] 

            for vertice in vertices:
                path = QPainterPath()
                for i, p in enumerate(vertice):

                    point = QPointF(*coords[i])
                    if i == 0:
                        path.moveTo(point)
                    else:
                        path.lineTo(point)
                self.paths.append(path)

            self.update()

        self.conf_yes = True

        self.startalgobtn.setVisible(True)
        self.exitbtn.setVisible(True)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    con_point_app = MainWindow()
    sys.exit(app.exec_())

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