How to set fixed width/height in Enaml grid container

Question

I have just come across Enaml for python GUI programming. I only used PySide2 once before for a simple calculator GUI mockup, so I'm new to both Qt and Enaml. Forgive my ignorance ;)

Essentially, I want to have a regular grid of Field or other elements, with fixed, square sizes. After going over some of the examples, I came up with:

from enaml.layout.api import grid
from enaml.widgets.api import Window, Container, Field


enamldef DigitField(Field):
    # The fields will contain a single digit for testing.
    mask = 'D'
    max_length = 1
    # These don't have any effect?
    hug_width = 'required'
    hug_height = 'required'

enamldef Main(Window):
    Container:
        constraints = [
            grid(
                [f11, f12],
                [f21, f22],
            ),
        ]

        DigitField: f11:
            text = '1'
        DigitField: f12:
            text = '1'

        DigitField: f21:
            text = '1'
        DigitField: f22:
            text = '1'

But the hug_width and hug_height don't seem to work. I then tried manually setting f11.width == 50, for example, inside the constraints, but the kiwisolver shouts at me about unresolvable constraints. I tried everything I could find from the examples about setting width values, but stuff that works for vbox doesn't seem to play with grid.

Any ideas? Also, if someone has a full app made with Enaml, that is open source, I would love to take a look. The docs are OK but some more advanced examples would be awesome.

Answer 1

Well, I think I have found a way to make it work. hug_width restricts width to the field content plus some default padding (from the Qt toolkit). Instead, using resist_width = 'ignore' I was able to completely remove the padding. The grid can be generated using a manual or an automatic method.

The manual method:

from enaml.layout.api import grid
from enaml.widgets.api import Window, Container, Field


enamldef DigitField(Field):
    # The fields will contain a single digit for testing.
    mask = 'D'
    max_length = 1
    resist_width = 'ignore'
    resist_height = 'ignore'

enamldef Main(Window):
    Container:
        constraints = [
            grid(
                [f11, f12],
                [f21, f22],
            ),
            f11.width == f11.height,
            f12.width == f12.height,
        ]

        DigitField: f11:
            text = '1'
        DigitField: f12:
            text = '1'

        DigitField: f21:
            text = '1'
        DigitField: f22:
            text = '1'

This is too WET and scales horribly, so instead we have...

The factory method:

from itertools import zip_longest

from enaml.core.api import Include
from enaml.layout.api import align, grid, factory
from enaml.widgets.api import Window, Container, Field


enamldef DigitField(Field):
    mask = 'D'
    max_length = 1
    resist_width = 'ignore'
    resist_height = 'ignore'

def generate_grid(container, num_cols):
    rows = []
    widgets = container.visible_widgets()
    row_iters = (iter(widgets),) * num_cols
    rows = list(zip_longest(*row_iters))
    return [grid(*rows), align('width', *widgets)]

enamldef Main(Window):
    Container:
        Container:
            constraints << [factory(generate_grid, 3)]
            Include:
                objects << [DigitField(text=str(1)) for i in range(9)]

I have nested the Container because there will probably be other things in the main window as well, and Enaml windows require a single master Container.