Pen and Brush Configuration

In the previous section, we learned the basic methods of drawing shapes. In this section, we'll learn about pen and brush configuration.

Pen Object (QPen)

The pen is primarily used to configure the thickness, color, style, etc., of shape outlines.

Common Pen Methods	Description
setColor()	Set the pen color
setWidth()	Set the pen width
setStyle()	Set the style: ● Qt.SolidLine: Regular solid line

Brush Object (QBrush)

The brush is primarily used to fill geometric shapes with color.

Common Brush Methods	Description
setColor()	Set the brush color
setStyle()	Set the style: ● Qt.SolidPattern: Solid fill

Example

Example: Change the line width of all shapes from the previous section to 5, fill the rectangle with red, and fill the circle with blue.

Here's the implementation code:

# -*- coding: utf-8 -*-

# pyQT5 For WalnutPi

from PyQt5 import QtCore, QtGui, QtWidgets

from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPainter,QPen,QBrush
from PyQt5.QtWidgets import QWidget

class Window(QWidget):
    
    def __init__(self):
        super().__init__() # Execute the parent QWidget's __init__ as well
        self.setWindowTitle("WalnutPi Paint") # Set window title
        self.resize(480,320) # Set window size
        
        # Window background color setting
        self.setObjectName("Paint_Window")
        self.setStyleSheet("#Paint_Window{background-color: black}") # Black

    def paintEvent(self,event):
        
        painter=QPainter(self) # Create drawing object
        
        # Pen configuration:
        pen = QPen()
        pen.setColor(Qt.green) # Green
        pen.setWidth(5) # Width 5
        painter.setPen(pen)
        
        # Brush configuration
        brush = QBrush()
        brush.setColor(Qt.red) # Red
        brush.setStyle(Qt.SolidPattern) # Fill
        painter.setBrush(brush) 
        
        painter.drawPoint(10,10) # Draw point
        
        painter.drawLine(20, 10, 80, 10) # Draw line
        
        painter.drawRect(100, 10, 80, 40) # Draw rectangle
        
        # Reconfigure brush, blue
        brush.setColor(Qt.blue)
        painter.setBrush(brush) 
        painter.drawEllipse(200, 10, 50, 50) # Draw circle
        

#################
#   Main Code    #
#################
import sys

# [Optional] Allow Thonny remote execution
import os
os.environ["DISPLAY"] = ":0.0"

# [Optional] Fix display issues on 2K+ resolution monitors
QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)

# Main program entry — build and display the window
app = QtWidgets.QApplication(sys.argv)
window = Window() # Create window object
window.show() # Show window
#window.showFullScreen() # Full-screen display

# [Recommended] Allow Ctrl+C to interrupt the window from terminal for easier debugging
import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)
timer = QtCore.QTimer()
timer.start(100)  # You may change this if you wish.
timer.timeout.connect(lambda: None)  # Let the interpreter run each 100 ms

sys.exit(app.exec_()) # Exit the process when the window is closed

The main difference from the previous code is the addition of pen and brush configuration:

    def paintEvent(self,event):

        ...

        # Pen configuration:
        pen = QPen()
        pen.setColor(Qt.green) # Green
        pen.setWidth(5) # Width 5
        painter.setPen(pen)
        
        # Brush configuration
        brush = QBrush()
        brush.setColor(Qt.red) # Red
        brush.setStyle(Qt.SolidPattern) # Fill
        painter.setBrush(brush) 

Additionally, the brush was initially set to red, so before drawing the circle after the rectangle, it needs to be reconfigured:

    ...
        # Reconfigure brush, blue
        brush.setColor(Qt.blue)
        painter.setBrush(brush) 
        painter.drawEllipse(200, 10, 50, 50) # Draw circle

The result is as follows: