Solved [PyQt5 5.15] QListWidgetItem.setSizeHint not working

[flashk]

I just updated from PyQT5 5.14.2 to 5.15 and setting the height of list items using QListWidgetItem.setSizeHint appears to have stopped working. Here is a simple example that worked in 5.14.2 and does not work with 5.15:

import sys
from PyQt5.QtWidgets import QApplication, QListWidget, QListWidgetItem, QMainWindow, QLabel
from PyQt5.QtCore import QSize

class MainWindow(QMainWindow):

	def __init__(self, *args, **kwargs):
		super(MainWindow, self).__init__(*args, **kwargs)
		self.setWindowTitle("List Widget Sample")

		listWidget = QListWidget()
		self.setCentralWidget(listWidget)

		for x in range(5):
			item = QListWidgetItem('item {}'.format(x+1))
			item.setSizeHint(QSize(-1, 100))
			listWidget.addItem(item)

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

Am I using the setSizeHint() method incorrectly or could this be a bug in the latest version? Is there a better way to set the height of list widget items?

[SGaist]

Hi and welcome to devnet,

I find a negative value for a size hint surprising.

Can you add a picture what you had before and now ?
By the way, which OS are you on ?

[flashk]

Hi, thanks for the reply.

I'm running on Windows 10.

Here is a before/after photo:

The default values for QListWidgetItem.sizeHint() is (-1, -1), so I assumed they are valid values. I just tried changing it to (0, 100), and it appears to work now. So I take it negative values are invalid, even though they are the default values? If I only want to apply the size hint to the height and keep the width stretched, is specifying 0 for the width considered the correct approach?

[JonB]

@flashk
https://doc.qt.io/qt-5/qsize.html#QSize

bool QSize::isValid() const

Returns true if both the width and height is equal to or greater than 0; otherwise returns false.

So technically QSize(-1, 100) could be treated as invalid. Perhaps behaviour now reflects this at 5.15.

[SGaist]

The default -1, -1 is explained in the constructor documentation. By default you create an invalid QSize if giving no parameters.

[flashk]

Great, thank you for the clarification!

[jeremy_k]

The behavior is indeed new with 5.15.

The change makes it possible to reset the background, foreground, or size hint by passing a default constructed QBrush or QSize.

https://github.com/qt/qtbase/commit/96c27eb710a37780e79e09df2ebce1d5e4922c9d