CODEWITHSUNDEEP
pythonuser-interfacepyqt4pyside
AnjoMan
AnjoMan

Reputation: 4918

How to add widgets dynamically after parent is created

I'm trying to build an interface using custom widgets, and have run into the following problem.

I have a widget Rectangle which I want to use as an interactive element in my interface. To define a rectangle I just need to give it a parent, so it knows what window to draw itself in, and a position [x,y, width, height] defining its position and size. (I know that some of you will say "You should be using layouts as opposed to absolute positioning" but I am 100% sure that I need absolute positioning for this particular application).

from PySide.QtCore import *
from PySide.QtGui import *
import sys

class Rectangle(QWidget):

    def __init__(self, parent, *args):
        super(self.__class__,self).__init__(parent)

        print parent, args
        #expect args[0] is a list in the form [x,y,width,height]
        self.setGeometry(*args[0])

    def enterEvent(self, e):
        print 'Enter'

    def leaveEvent(self, e):
        print 'Leave'

    def paintEvent(self, e):

        print 'Painted: ',self.pos
        painter = QPainter(self)
        painter.setPen(Qt.NoPen)
        painter.setBrush(QColor(200,100,100))
        painter.drawRect(0,0,self.width()-1, self.height()-1)
        painter.end()

I also have a Window widget which is the canvas on which my visualization is to be drawn. In the Window's __init__() definition I create a rectangle A at 20,40.

class Window(QWidget):

    def __init__(self):
        super(self.__class__, self).__init__()


        self.widgets = [Rectangle(self,[20,40,100,80])]
        self.setMouseTracking(True)
        self.setGeometry(300,300,800,600)
        self.setWindowTitle('Window')
        self.show()

    def addWidget(self,Widget, *args):
        self.widgets += [Widget(self, *args)]
        self.update()

    def mousePressEvent(self, e):
        for widget in self.widgets:
            print widget.geometry()

Since I am building a visualization, I want to create my Window and then add widgets to it afterwords, so I create an instance mWindow, which should already have rectangle A defined. I then use my window's addWidget() method to add a second rectangle at 200,200 - call it rectangle B.

if __name__ == "__main__":
    app= QApplication(sys.argv)

    mWindow = Window()
    mWindow.addWidget(Rectangle, [200,200,200,80])
    sys.exit(app.exec_())

The issue I have is that only rectangle A actually gets drawn.

I know that both rectangle A and **rectangle B are getting instantiated and both have myWindow as their parent widgets, because of the output of print parent in the constructor for Rectangle.

However, when I resize the window to force it to repaint itself, the paintEvent() method is only called on rectangle A, not rectangle B. What am I missing?

Upvotes: 2

Views: 1192

Answers (1)

mguijarr
mguijarr

Reputation: 7930

You just forgot to show the rectangle. In addWidget, add this before self.update():

self.widgets[-1].show()

The reason why you don't need show for the first rectangle object is because it is created in the Window constructor. Then, Qt itself is making sure objects are properly shown (which is misleading, I agree...).

Upvotes: 3

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