PyQt adding widget dynamically in front of existing ones

Question

What I want to archive is to create an (pixmap-)widget that is then visible in front of the main widget. Later on, this widget is supposed to follow the mouse.

So my main problem is to create an widget dynamically when the spacebar is pressed that is then visible in front of the other widgets, without creating a seperate window.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtCore import Qt


class MainWindow(QtWidgets.QMainWindow):

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

        self.label = QtWidgets.QLabel()
        canvas = QtGui.QPixmap(1200, 800)
        canvas.fill(QtGui.QColor('#ffffff')) # Fill entire canvas.
        self.label.setPixmap(canvas)
        self.setCentralWidget(self.label)

        self.last_x, self.last_y = None, None


    def mouseMoveEvent(self, e):
        if self.last_x is None: # First event.
            self.last_x = e.x()
            self.last_y = e.y()
            return # Ignore the first time.

        painter = QtGui.QPainter(self.label.pixmap())
        painter.drawLine(self.last_x, self.last_y, e.x(), e.y())
        painter.end()
        self.update()

        # Update the origin for next time.
        self.last_x = e.x()
        self.last_y = e.y()

    def mouseReleaseEvent(self, e):
        self.last_x = None
        self.last_y = None

    def keyPressEvent(self, QKeyEvent):
        if QKeyEvent.key() == Qt.Key_Space:
            block = QtGui.QPixmap(20, 20)
            block.fill(QtGui.QColor('blue'))
            self.image = QtWidgets.QLabel()
            self.image.setPixmap(block)
            self.image.move(20,20)
            # self.image.raise_()
            # self.image.show()

app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()

If I where to call .show() on the image a seperate window with this widget would be opened. But that is not what I want to archive. _raise doesn't seem to do anything at all.

Edit: can i achive this by using a QStackedLayout?

eyllanesc · Accepted Answer · 2020-10-02 19:20:58Z

2

A widget that does not have a parent will be shown as a window, so the solution is to pass it a parent and call the show() method to show it:

def keyPressEvent(self, QKeyEvent):
    if QKeyEvent.key() == Qt.Key_Space:
        block = QtGui.QPixmap(20, 20)
        block.fill(QtGui.QColor('blue'))
        self.image = QtWidgets.QLabel(self.label)
        self.image.setPixmap(block)
        self.image.move(20,20)
        self.image.show()

answered Oct 2, 2020 at 19:20

eyllanesc

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