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Details

Type: Bug
Resolution: Fixed
Priority: P2: Important
Fix Version/s: 6.8.0 Beta3, 6.9.0 FF
Affects Version/s: 6.7.2
Component/s: GUI: Painting
Labels:
None

Commits:
c7df8dda8 (dev), 051764ddf (6.8)

Description

When calling QPainter::drawText(QRectF, QString) with an invalid rect, e.g.

painter->drawText(QRectF(), "foo")

then nothing will be drawn unless the painter is rendering to a QSvgGenerator, in which case the text will be displayed at (0, 0). Here's a PySide6 script that demonstrates the issue, but we've experienced this with C++ code as well:

from PySide6 import QtWidgets, QtGui, QtCore, QtSvg
from PySide6.QtCore import Qt

app = QtWidgets.QApplication([])
widget = QtWidgets.QWidget()
layout = QtWidgets.QHBoxLayout(widget)
widget.setLayout(layout)
for test in ['invalid_SVG', 'valid_SVG', 'invalid_PXM', 'valid_PXM']:
    if 'invalid' in test:
        rect = QtCore.QRectF()  # invalid rect
    else:
        rect = QtCore.QRectF(25, 25, 75, 75)  # valid rect
    pixmap = QtGui.QPixmap(100, 100)
    painter = QtGui.QPainter()
    if 'SVG' in test:
        svg_gen = QtSvg.QSvgGenerator()
        buffer = QtCore.QBuffer()
        svg_gen.setOutputDevice(buffer)
        svg_gen.setSize(QtCore.QSize(100, 100))
        painter.begin(svg_gen)
    else:
        painter.begin(pixmap)
    painter.fillRect(QtCore.QRect(0, 0, 100, 100), Qt.white)
    painter.setPen(Qt.black)
    painter.drawText(rect, test)
    painter.end()
    if 'SVG' in test:
        pixmap.loadFromData(buffer.data(), "SVG")
    label = QtWidgets.QLabel(widget)
    layout.addWidget(label)
    label.setPixmap(pixmap)
widget.show()
app.exec()

This script generates

As you can see, "invalid_SVG" is rendered to the upper-left corner of the first image, but nothing is rendered to the third image (where the text is rendered to an invalid QRectF in a pixmap).