Dynamically paint or draw filled and coloured rectangle using pyqt

jacha

I've created a simple gui using qt-designer and python. I would like to dynamically create a rectangle (with fill and colour) by adjusting a slider in the gui. I have managed to do this with a dashed line rectangle but I think that is the limit of drawRecangle. This is what I have:

from PyQt5 import QtWidgets, uic, QtGui, QtCore
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import*  
from matplotlib.backends.backend_qt5agg import (NavigationToolbar2QT as NavigationToolbar)
from matplotlib.patches import Rectangle
import sys

class MainWindow(QtWidgets.QMainWindow):
    
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
    
        #Load the UI Page
        uic.loadUi('mainwindow.ui', self)

        global slider_widget
        slider_widget = self.findChild(QtWidgets.QSlider, "verticalSlider")
        slider_widget.valueChanged.connect(self.valueChanged)
    
        self.update_paintwidget()
        self.update_graph()
    
    def update_paintwidget(self):
        self.PaintWidget.paintEvent
    
    def update_graph(self):
        self.MplWidget.canvas.drawRectangle((10,200,100,0))
    
    def valueChanged(self):
        global val 
        val = slider_widget.value()
        self.MplWidget.canvas.drawRectangle((10,100-((val*2)-100),100,100+((val*2)-100)))

def main():
    app = QtWidgets.QApplication(sys.argv)
    main = MainWindow()
    main.show()
    sys.exit(app.exec_())

if __name__ == '__main__':      
    main()

I have a separate widget (promoted in qt designer) to dynamically draw the rectangle. I cannot however colour the lines of the rectangle or fill in with a colour. It is just dashed black lines.

mplwidget.py

from PyQt5.QtWidgets import*

from matplotlib.backends.backend_qt5agg import FigureCanvas

from matplotlib.figure import Figure

class MplWidget(QWidget):

    def __init__(self,parent = None):

        QWidget.__init__(self, parent)
        self.canvas = FigureCanvas(Figure())
        vertical_layout = QVBoxLayout()
        vertical_layout.addWidget(self.canvas)
        self.setLayout(vertical_layout)

I've tried using paintevent and can create a rectange but I can't figure out how to dynamically pass the co-ordinate values to it.

paintwidget.py

from PyQt5 import QtCore, QtGui, Qt
from PyQt5.QtWidgets import*

class PaintWidget(QWidget):

    def __init__(self,parent = None):
        QWidget.__init__(self, parent)

    def paintEvent(self,event): #,event
        qp = QtGui.QPainter(self)
        qp.setPen(QtGui.QPen(QtCore.Qt.red))
        qp.drawRect(10, 15, 20, 20)

Is this possible?

SGaist

Hi and welcome to devnet,

You should add a setter to your widget to pass it the coordinates you want.

On a side note, you should call update and not try to call the paintEvent method directly.

Depending on your end goal, you might want to consider the Graphics View framework.