QSGGeometry does not work on PySide2

SGaist

Did you open an issue on the bug tracker ?

Advig

SGaist

Thank you !

Advig

@SGaist : Do you know any easy way I could write a patch for this. I am not sure if I will get a solution soon from bug tracking system.

Yossip

I am facing the same issue. This basically makes writing custom QQuickItems in Python impossible.

Also, I am hitting this issue with PySide6.

The bug that was reported is stuck nowhere.

Yossip

Quick update. I reviewed the ticket again and realized there is a patch there. I recomplied PySide6 with the patch applied and I can say that vertexDataAsPoint2D() now does return a list of Point2D instead of just Point2D. In the ticket the developer states that the fix crashes submitted example. I am yet to confirm whether this causes any issues on my side.

Yossip

Ok, I have the same problem as mentioned in the ticket - it segfaults.

To summarize, you cannot write custom QQuickItems in Python at this time.

SGaist

Thanks for the feedback !

Can you upload your minimal example on the report ?
It can help fix this issue as well.

Yossip1

Hi SGaist,

Here's the code. It's really basic:

# This Python file uses the following encoding: utf-8
import os
from pathlib import Path
import sys

from PySide6.QtGui import QGuiApplication, QColor
from PySide6.QtQml import QQmlApplicationEngine, qmlRegisterType
from PySide6.QtQuick import QQuickItem, QSGGeometryNode, QSGGeometry, QSGFlatColorMaterial, QSGNode


class JustItem(QQuickItem):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setFlag(QQuickItem.ItemHasContents, enabled=True)


    def updatePaintNode(self, node, update_data):
        if node is None:
            node = QSGGeometryNode()
            geometry = QSGGeometry(QSGGeometry.defaultAttributes_Point2D(), 4)
            geometry.setLineWidth(1)
            geometry.setDrawingMode(QSGGeometry.DrawTriangles)


            material = QSGFlatColorMaterial()
            material.setColor(QColor(255, 0, 0, 127))

            node.setGeometry(geometry)
            node.setMaterial(material)
            node.setFlag(QSGNode.OwnsGeometry)
            node.setFlag(QSGNode.OwnsMaterial)
        else:
            geometry = node

        vertex_data = geometry.vertexDataAsPoint2D()

        vertex_data[0].set(10, 10)
        vertex_data[1].set(100, 10)
        vertex_data[2].set(100, 100)
        vertex_data[3].set(10, 100)
        node.markDirty(QSGNode.DirtyGeometry)

        return node


if __name__ == "__main__":
    qmlRegisterType(JustItem, "PythonTypes", 1, 0, "JustItem")

    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    engine.load(os.fspath(Path(__file__).resolve().parent / "main.qml"))


    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec())

and main.qml:

import QtQuick
import QtQuick.Window
import PythonTypes 1.0

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    JustItem {

    }
}

If you run it without the patch, it will complain that Point2D is not subscriptible (because Point2D and not a list of Point2Ds is returned). If you run it with the patch applied, it will segfault.

SGaist

Thanks for posting it here but you should add it to the bug report as well. It will be easier to find over there.