I’m making a GUI using PyQt5 where I have hexagonal cells that have a button that is part of a circle at some vertex. However, I can’t find a way to make the clickable area of the button be the arc, and nothing but the arc. Even when I create a “slice” widget and paint it, there is either a clickable area outside of the slice (making a clickable area of a rectangle), or the clickable area is too small. How can I make a button of the correct shape?
Here is a stripped-down version of my code. The button position is determined by the channel_pos argument for the Hex class; 0 is the top vertex and they are numbered clockwise around the hexagon.

import sys, csv
import numpy as np
import pandas as pd
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QLabel
from PyQt5.QtCore import Qt, QRectF, QRect, QPoint, QPointF
from PyQt5.QtGui import QPainter, QPen, QColor, QRegion, QPainterPath, QPolygonF
from PyQt5.QtWidgets import QWidget, QScrollArea, QVBoxLayout

class Hex(QWidget): #pads
    def __init__(self, buttons, state, radius, cell_id, label_pos, channel_id, channel_pos, color, parent=None):
        super().__init__(parent)
        self.cell_id = cell_id
        self.label_pos = label_pos
        self.radius = radius
        self.state = state
        self.color = color
        self.channel_id = channel_id
        self.channel_pos = channel_pos
        #make button, store it in button dict
        self.button2 = WedgeButton(self.state, channel_id, self.channel_pos, ' ',
            [self.radius/3*np.cos(channel_pos*np.pi/3 + np.pi/2),self.radius/3*np.sin(channel_pos*np.pi/3 + np.pi/2)], self.radius/1.5, self)
        buttons[cell_id] = self.button2
        
    def paintEvent(self, event):
        #draw pad
        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)
        vertices = [QPointF(self.radius * np.cos(x*np.pi/3 + np.pi/2) + self.radius, self.radius * np.sin(x*np.pi/3 + np.pi/2) + self.radius) for x in range (0,6)]
        polygon = QPolygonF(vertices)
        pen = QPen(QColor(self.color))
        painter.setPen(pen)
        painter.setBrush(QColor(self.color))
        painter.drawPolygon(polygon)
        
        # Draw label
        font = painter.font()
        font.setPointSize(9)
        painter.setFont(font)
        pen = QPen(Qt.black)
        painter.setPen(pen)
        
        #based on position number of channel, calculate position of button within pad
        angle = 3*np.pi/2 + self.channel_pos*np.pi/3 #angle from center of cell to vertex identified by channel_pos
        self.button2.setGeometry(int(self.radius - self.button2.radius + self.radius*np.cos(angle)), 
            int(self.radius - self.button2.radius + self.radius*np.sin(angle)),int(self.button2.radius*2),int(self.button2.radius*2))
        self.button2.show()

class WedgeButton(QPushButton):
    #whether or not front side buttons are active
    active = 0
    def __init__(self, state, channel_id, channel_pos, label, label_pos, radius, parent=None):
        super().__init__(parent)
        self.channel_id = channel_id
        self.channel_pos = channel_pos
        self.label_pos = label_pos
        self.label = label
        self.state = int(state)
        self.radius = radius
        self.clicked.connect(self.changeState)

    def changeState(self):
        old_state = self.state
        self.state = (self.state + 1) % 4
        self.update()

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)
        rect = QRectF(0, 0, self.width(), self.height())
        pen = QPen(Qt.black)
        painter.setPen(pen)
        if self.state == 0:
            painter.setBrush(QColor('#3498db'))
            pen.setColor(QColor('#3498db'))
        elif self.state == 1:
            painter.setBrush(Qt.yellow)
            pen.setColor(Qt.yellow)
        elif self.state == 3:
            painter.setBrush(Qt.red)
            pen.setColor(Qt.red)
        elif self.state == 2:
            painter.setBrush(QColor('#ffbc36'))
            pen.setColor(QColor('#ffbc36'))
        
        painter.setPen(pen)
        
        start_angle = ((210-self.channel_pos*60)*16)%(360*16)
        span_angle  = 120*16
        painter.drawPie(0,0,int(2*self.radius),int(2*self.radius), start_angle, span_angle)
        
class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setGeometry(0, 0, 1000, 900)

        self.scroll = QScrollArea()
        self.scroll.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
        self.scroll.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.scroll.setWidgetResizable(True)  # Allow the widget inside the scroll area to resize
        self.setCentralWidget(self.scroll)

        self.widget = QWidget()
        self.scroll.setWidget(self.widget)
        self.vbox = QVBoxLayout()  # Create a layout for the buttons
        self.widget.setLayout(self.vbox)  # Set the layout for the widget contained within the scroll area
        self.widget.adjustSize()
        self.buttons = {}
        
        pad = Hex(self.buttons,  0,
                30, 0, [0,18], 0, 
                0, '#d1dbe8', 
                parent = self.widget)
        pad.setGeometry(500, 500, pad.radius*2, pad.radius*2)
        
if __name__ == "__main__":
    app = QApplication(sys.argv)
    mainWindow = MainWindow()
    mainWindow.show()
    sys.exit(app.exec_())

I tried using a setting a mask for the area, but that produced the same issues and was very pixellated.