LinearRelations Example

linear_relations.enaml

#------------------------------------------------------------------------------
#  Copyright (c) 2012, Enthought, Inc.
#  All rights reserved.
#------------------------------------------------------------------------------
""" An example which demonstrates linear relational constraints.

This example shows how one may define a constraint as a linear relation
of some other constraint. In this example, the horizontal position and
width of a `PushButton` depends up the width of the `Container`, and the 
vertical position of another `PushButton` depends upon the width of the 
other `PushButton`.

This is a contrieved example, but serves to demonstrate the feature.

"""
from enaml.widgets.api import Window, Container, PushButton


enamldef Main(Window):
    Container:
        constraints = [
            # Pin the first push button to the top contents anchor.
            pb1.top == contents_top,

            # Relate the left side of the push button to the width
            # of the container.
            pb1.left == 0.3 * width,

            # Relate the width of the push button to the width of 
            # the container
            pb1.width == 0.5 * width, 

            # Pin the second push button to the left contents anchor.
            pb2.left == contents_left,

            # Relate the top of the push button to width of the first
            # push button.
            pb2.top == 0.3 * pb1.width + 10
        ]
        PushButton:
            id: pb1
            text = 'Horizontal'
        PushButton:
            id: pb2
            text = 'Long Name Foo'

$ enaml-run linear_relations.enaml