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%%html
<style>
.example-container { background: #999999; padding: 2px; min-height: 100px; }
.example-container.sm { min-height: 50px; }
.example-box { background: #9999FF; width: 50px; height: 50px; text-align: center; vertical-align: middle; color: white; font-weight: bold; margin: 2px;}
.example-box.med { width: 65px; height: 65px; }   
.example-box.lrg { width: 80px; height: 80px; }   
</style>
In [ ]:
from IPython.html import widgets
from IPython.display import display

Widget Styling

Basic styling

The widgets distributed with IPython can be styled by setting the following traits:

  • width
  • height
  • fore_color
  • back_color
  • border_color
  • border_width
  • border_style
  • font_style
  • font_weight
  • font_size
  • font_family

The example below shows how a Button widget can be styled:

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button = widgets.Button(
    description='Hello World!',
    width=100, # Integers are interpreted as pixel measurements.
    height='2em', # em is valid HTML unit of measurement.
    color='lime', # Colors can be set by name,
    background_color='#0022FF', # and also by color code.
    border_color='red')
display(button)

Parent/child relationships

To display widget A inside widget B, widget A must be a child of widget B. Widgets that can contain other widgets have a children attribute. This attribute can be set via a keyword argument in the widget's constructor or after construction. Calling display on an object with children automatically displays those children, too.

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from IPython.display import display

float_range = widgets.FloatSlider()
string = widgets.Text(value='hi')
container = widgets.Box(children=[float_range, string])

container.border_color = 'red'
container.border_style = 'dotted'
container.border_width = 3
display(container) # Displays the `container` and all of it's children.

After the parent is displayed

Children can be added to parents after the parent has been displayed. The parent is responsible for rendering its children.

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container = widgets.Box()
container.border_color = 'red'
container.border_style = 'dotted'
container.border_width = 3
display(container)

int_range = widgets.IntSlider()
container.children=[int_range]

Fancy boxes

If you need to display a more complicated set of widgets, there are specialized containers that you can use. To display multiple sets of widgets, you can use an Accordion or a Tab in combination with one Box per set of widgets (as seen below). The "pages" of these widgets are their children. To set the titles of the pages, one can call set_title.

Accordion

In [ ]:
name1 = widgets.Text(description='Location:')
zip1 = widgets.BoundedIntText(description='Zip:', min=0, max=99999)
page1 = widgets.Box(children=[name1, zip1])

name2 = widgets.Text(description='Location:')
zip2 = widgets.BoundedIntText(description='Zip:', min=0, max=99999)
page2 = widgets.Box(children=[name2, zip2])

accord = widgets.Accordion(children=[page1, page2])
display(accord)

accord.set_title(0, 'From')
accord.set_title(1, 'To')

TabWidget

In [ ]:
name = widgets.Text(description='Name:')
color = widgets.Dropdown(description='Color:', options=['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet'])
page1 = widgets.Box(children=[name, color])

age = widgets.IntSlider(description='Age:', min=0, max=120, value=50)
gender = widgets.RadioButtons(description='Gender:', options=['male', 'female'])
page2 = widgets.Box(children=[age, gender])

tabs = widgets.Tab(children=[page1, page2])
display(tabs)

tabs.set_title(0, 'Name')
tabs.set_title(1, 'Details')

Alignment

Most widgets have a description attribute, which allows a label for the widget to be defined. The label of the widget has a fixed minimum width. The text of the label is always right aligned and the widget is left aligned:

In [ ]:
display(widgets.Text(description="a:"))
display(widgets.Text(description="aa:"))
display(widgets.Text(description="aaa:"))

If a label is longer than the minimum width, the widget is shifted to the right:

In [ ]:
display(widgets.Text(description="a:"))
display(widgets.Text(description="aa:"))
display(widgets.Text(description="aaa:"))
display(widgets.Text(description="aaaaaaaaaaaaaaaaaa:"))

If a description is not set for the widget, the label is not displayed:

In [ ]:
display(widgets.Text(description="a:"))
display(widgets.Text(description="aa:"))
display(widgets.Text(description="aaa:"))
display(widgets.Text())

Flex boxes

Widgets can be aligned using the FlexBox, HBox, and VBox widgets.

Application to widgets

Widgets display vertically by default:

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buttons = [widgets.Button(description=str(i)) for i in range(3)]
display(*buttons)

Using hbox

To make widgets display horizontally, you need to child them to a HBox widget.

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container = widgets.HBox(children=buttons)
display(container)

By setting the width of the container to 100% and its pack to center, you can center the buttons.

In [ ]:
container.width = '100%'
container.pack = 'center'

Visibility

Sometimes it is necessary to hide or show widgets in place, without having to re-display the widget. The visible property of widgets can be used to hide or show widgets that have already been displayed (as seen below). The visible property can be:

  • True - the widget is displayed
  • False - the widget is hidden, and the empty space where the widget would be is collapsed
  • None - the widget is hidden, and the empty space where the widget would be is shown
In [ ]:
w1 = widgets.Latex(value="First line")
w2 = widgets.Latex(value="Second line")
w3 = widgets.Latex(value="Third line")
display(w1, w2, w3)
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w2.visible=None
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w2.visible=False
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w2.visible=True

Another example

In the example below, a form is rendered, which conditionally displays widgets depending on the state of other widgets. Try toggling the student checkbox.

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form = widgets.VBox()
first = widgets.Text(description="First Name:")
last = widgets.Text(description="Last Name:")

student = widgets.Checkbox(description="Student:", value=False)
school_info = widgets.VBox(visible=False, children=[
    widgets.Text(description="School:"),
    widgets.IntText(description="Grade:", min=0, max=12)
    ])

pet = widgets.Text(description="Pet's Name:")
form.children = [first, last, student, school_info, pet]
display(form)

def on_student_toggle(name, value):
    if value:
        school_info.visible = True
    else:
        school_info.visible = False
student.on_trait_change(on_student_toggle, 'value')