How to set a PySide6 QTableWidget column width to 15pt?

Question

I'd like to create a small table widget with buttons in column #2. The buttons are thin (15pt) as they only contain a T.

Here is a small working example.

import sys
from PySide6.QtWidgets import (
    QMainWindow, QApplication, QTableWidget, QLabel, QPushButton
)
from PySide6.QtCore import Qt

class MainWindow(QMainWindow):

    def __init__(self):
        super(MainWindow, self).__init__()
        self.setWindowTitle("My App")

        Nrows, Ncols = 5, 3
        table = QTableWidget(Nrows, Ncols, self)

        for col in [0, 2]:
            for row in range(Nrows):
                table.setCellWidget(row, col,
                    QLabel(f"row {row} column {col}")
                )
        for row in range(Nrows):
            push = QPushButton("T")
            push.setFixedWidth(15)
            table.setCellWidget(row, 1,push)

        self.setCentralWidget(table)

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

This produces the following window.

The problem is that I want the push button column to be 15pt with at startup too. So that the column width is the same width as the push button.

The two problems are:

1. I need to resize at startup
2. Resizing does not goes down to 15pt. It seems the column width can not be under approx. 20pt.

How can this be resolved?

Answer 1

The default minimum section size is computed by the current style and font.

You can override the size of a section by using setColumnWidth():

table.setColumnWidth(1, 15)

Which is the same as using resizeSection of the header:

table.horizontalHeader().resizeSection(1, 15)

But you should also ensure that the minimum section is set, otherwise if the user tries to resize the section, it will fall back to the default minimum:

table.horizontalHeader().setMinimumSectionSize(15)

Note that you can also use the setSectionResizeMode() (but you still must set the minimum section size):

table.horizontalHeader().setMinimumSectionSize(15)
table.horizontalHeader().setSectionResizeMode(1, QHeaderView.ResizeToContents)

Note that a button width of 15 is really too narrow, and you cannot rely on your computer font: other users might have different styles (which add bigger margins between text and button borders) or fonts bigger than yours; you should ensure that the minimum width is based on the font and style, and also always provide the possibility to adjust the size:

width = (
    self.fontMetrics().horizontalAdvance("T")
    + self.style().pixelMetric(QStyle.PM_ButtonMargin) * 2
    + self.style().pixelMetric(QStyle.PM_DefaultFrameWidth) * 2
)

for row in range(Nrows):
    push = QPushButton("T")
    push.setMinimumWidth(width) # set a *minimum* width, not a fixed one
    table.setCellWidget(row, 1, push)
table.horizontalHeader().setMinimumSectionSize(width)
table.setColumnWidth(1, width)