Mpl Canvas Size Example

An example of how to override tolkit-supplied size hints on your widget.

The toolkit-supplied size hint for MPLCanvas is 480 x 640 pixels, which prevents you from sizing the canvas smaller. This can be a problem when you are presenting a large grid of Matplotlib figures.

This example demonstrates how to override the tookit-supplied size hint for MPLCanvas. By setting resist_width, resist_height, hug_height, and hug_width to ‘ignore’, you can resize the figure almost freely in any direction.

This serves to demonstrate how the resist, hug and limit constraints interact to control the size of a widget.

resist:

If “strong”, the widget will not shrink smaller than the preferred size (i.e., the constraint width >= width_hint or height >= height_hint is set on the object).

hug:

If “strong”, the widget will not change from the preferred size (i.e., the constraint width == width_hint or height == height_hint is set on the object).

limit:

If “strong”, the widget will not expand larger than the preferred size (i.e., the constraint width <= width_hint and height <= height_hint is set on the object).

To allow a MPLCanvas to shrink smaller than the default size but not expand larger:

resist = ignore or weak hug = ignore or weak limit = strong

To allow a MPLCanvas to expand larger than the default size but not shrink smaller:

resist = strong hug = ignore or weak limit = ignore or weak

To disallow a MPLCanvas to change in size:

resist = strong, ignore or weak hug = strong limit = strong, ignore or weak

Tip

To see this example in action, download it from mpl_canvas_size and run:

$ enaml-run mpl_canvas_size.enaml

Screenshot

Example Enaml Code

#------------------------------------------------------------------------------
# Copyright (c) 2022, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
#------------------------------------------------------------------------------
""" An example of how to override tolkit-supplied size hints on your widget.


The toolkit-supplied size hint for MPLCanvas is 480 x 640 pixels, which
prevents you from sizing the canvas smaller. This can be a problem when you are
presenting a large grid of Matplotlib figures.

This example demonstrates how to override the tookit-supplied size hint for
MPLCanvas. By setting resist_width, resist_height, hug_height, and hug_width to
'ignore', you can resize the figure almost freely in any direction.

This serves to demonstrate how the resist, hug and limit constraints interact
to control the size of a widget.

resist:
    If "strong", the widget will not shrink smaller than the preferred size
    (i.e., the constraint `width >= width_hint` or `height >= height_hint` is
    set on the object).

hug:
    If "strong", the widget will not change from the preferred size (i.e., the
    constraint `width == width_hint` or `height == height_hint` is set on the
    object).

limit:
    If "strong", the widget will not expand larger than the preferred size
    (i.e., the constraint `width <= width_hint` and `height <= height_hint` is
    set on the object).

To allow a MPLCanvas to shrink smaller than the default size but not expand
larger:

    resist = ignore or weak
    hug = ignore or weak
    limit = strong

To allow a MPLCanvas to expand larger than the default size but not shrink
smaller:

    resist = strong
    hug = ignore or weak
    limit = ignore or weak


To disallow a MPLCanvas to change in size:

    resist = strong, ignore or weak
    hug = strong
    limit = strong, ignore or weak


<< autodoc-me >>
"""

import matplotlib.pyplot as plt
import numpy as np

from enaml.widgets.api import (Form, Label, MPLCanvas, ObjectCombo, VGroup,
                               Window)


def make_figure():
    # Constrained layout uses the kiwisolver engine and will ensure that the
    # axes are formatted properly regardless of the size of the figure.
    figure, axes = plt.subplots(constrained_layout=True)
    x = np.arange(1000) / 1000
    y = np.sin(2 * np.pi * 5 * x)
    axes.plot(x, y)
    return figure


enamldef Main(Window):

    Form:
        Label:
            text = 'resist_height and resist_width'

        ObjectCombo: resist:
            items = ['strong', 'weak', 'ignore']

        Label:
            text = 'hug_height and hug_width'

        ObjectCombo: hug:
            items = ['strong', 'weak', 'ignore']

        Label:
            text = 'limit_height and limit_width'

        ObjectCombo: limit:
            items = ['strong', 'weak', 'ignore']

        MPLCanvas: canvas:
            resist_width << resist.selected
            resist_height << resist.selected
            hug_width << hug.selected
            hug_height << hug.selected
            limit_width << limit.selected
            limit_height << limit.selected

            # This specifies the minimum possible size for the window.
            constraints = [(width >= 100) | 'strong', (height >= 100) | 'strong']
            figure = make_figure()