CameraSnapshotWidget

class menpowidgets.options.CameraSnapshotWidget(canvas_width=640, hd=True, n_preview_windows=5, preview_windows_margin=3, render_function=None, style='minimal', preview_style='minimal')[source]

Bases: MenpoWidget

Creates a webcam widget for taking screenshots. The widget consists of the following objects from ipywidgets and menpowidgets.tools:

No Object Property (self.) Description
1 CameraWidget camera_wid The webcam widget
2 Latex n_snapshots_text Number of snapshots
3 Button snapshot_but Take snapshot button
4 VBox snapshot_box Contains 3, 2
5 Button close_but Close widget button
8 ZoomOneScaleWidget zoom_widget Resolution controller
9 HBox buttons_box Contains 3, 5, 8
10 Image preview_children List of preview images
11 HBox preview Contains all 10

Note that:

  • The selected values are stored in the self.selected_values trait.
  • To set the styling of this widget please refer to the style() and predefined_style() methods.
  • To update the handler callback function of the widget, please refer to the replace_render_function() method.
Parameters:
  • canvas_width (int, optional) – The initial width of the rendered canvas. Note that this doesn’t actually change the webcam resolution. It simply rescales the rendered image, as well as the size of the returned screenshots.
  • hd (bool, optional) – If True, then the webcam will be set to high definition (HD), i.e. 720 x 1280. Otherwise the default resolution will be used.
  • n_preview_windows (int, optional) – The number of preview thumbnails that will be used as a FIFO stack to show the captured screenshots. It must be at least 4.
  • preview_windows_margin (int, optional) – The margin between the preview thumbnails in pixels.
  • render_function (callable or None, optional) –

    The render function that is executed when a widgets’ value changes. It must have signature render_function(change) where change is a dict with the following keys:

    • type : The type of notification (normally 'change').
    • owner : the HasTraits instance
    • old : the old value of the modified trait attribute
    • new : the new value of the modified trait attribute
    • name : the name of the modified trait attribute.

    If None, then nothing is assigned.

  • style (str (see below), optional) –

    Sets a predefined style at the widget. Possible options are:

    Style Description
    'minimal' Simple black and white style
    'success' Green-based style
    'info' Blue-based style
    'warning' Yellow-based style
    'danger' Red-based style
    '' No style
  • preview_style (str (see below), optional) –

    Sets a predefined style at the widget’s preview box. Possible options are:

    Style Description
    'minimal' Simple black and white style
    'success' Green-based style
    'info' Blue-based style
    'warning' Yellow-based style
    'danger' Red-based style
    '' No style

Example

Let’s create a webcam widget. Firstly, we need to import it:

>>> from menpowidgets.options import CameraSnapshotWidget

Create the widget with some initial options and display it:

>>> wid = CameraSnapshotWidget(canvas_width=640, hd=True,
>>>                            n_preview_windows=5,
>>>                            preview_windows_margin=1, style='info')
>>> wid

By pressing the “Take snapshot” button, the snapshots appear in the thumbnails below the stream. The video stream can be interrupted by pressing the “Close” button.

add_render_function(render_function)

Method that adds the provided render_function() as a callback handler to the selected_values trait of the widget. The given function is also stored in self._render_function.

Parameters:render_function (callable or None, optional) –

The render function that behaves as a callback handler of the selected_values trait for the change event. Its signature can be render_function() or render_function(change), where change is a dict with the following keys:

  • owner : the HasTraits instance
  • old : the old value of the modified trait attribute
  • new : the new value of the modified trait attribute
  • name : the name of the modified trait attribute.
  • type : 'change'

If None, then nothing is added.

add_traits(**traits)

Dynamically add trait attributes to the Widget.

call_render_function(old_value, new_value, type_value='change')

Method that calls the existing render_function() callback handler.

Parameters:
  • old_value (int or float or dict or list or tuple) – The old selected_values value.
  • new_value (int or float or dict or list or tuple) – The new selected_values value.
  • type_value (str, optional) – The trait event type.
close()

Close method.

Closes the underlying comm. When the comm is closed, all of the widget views are automatically removed from the front-end.

has_trait(name)

Returns True if the object has a trait with the specified name.

observe(handler, names=traitlets.All, type='change')

Setup a handler to be called when a trait changes.

This is used to setup dynamic notifications of trait changes.

Parameters:
  • handler (callable) – A callable that is called when a trait changes. Its signature should be handler(change), where change```is a dictionary. The change dictionary at least holds a 'type' key. * ``type: the type of notification. Other keys may be passed depending on the value of ‘type’. In the case where type is ‘change’, we also have the following keys: * owner : the HasTraits instance * old : the old value of the modified trait attribute * new : the new value of the modified trait attribute * name : the name of the modified trait attribute.
  • names (list, str, All) – If names is All, the handler will apply to all traits. If a list of str, handler will apply to all names in the list. If a str, the handler will apply just to that name.
  • type (str, All (default: 'change')) – The type of notification to filter by. If equal to All, then all notifications are passed to the observe handler.
predefined_style(style, preview_style='minimal')[source]

Function that sets a predefined style on the widget.

Parameters:
  • style (str (see below)) –

    Style options:

    Style Description
    'minimal' Simple black and white style
    'success' Green-based style
    'info' Blue-based style
    'warning' Yellow-based style
    'danger' Red-based style
    '' No style
  • preview_style (str (see below)) –

    Preview box style options:

    Style Description
    'minimal' Simple black and white style
    'success' Green-based style
    'info' Blue-based style
    'warning' Yellow-based style
    'danger' Red-based style
    '' No style
remove_render_function()

Method that removes the current self._render_function() as a callback handler to the selected_values trait of the widget and sets self._render_function = None.

replace_render_function(render_function)

Method that replaces the current self._render_function() with the given render_function() as a callback handler to the selected_values trait of the widget.

Parameters:render_function (callable or None, optional) –

The render function that behaves as a callback handler of the selected_values trait for the change event. Its signature can be render_function() or render_function(change), where change is a dict with the following keys:

  • owner : the HasTraits instance
  • old : the old value of the modified trait attribute
  • new : the new value of the modified trait attribute
  • name : the name of the modified trait attribute.
  • type : 'change'

If None, then nothing is added.

style(box_style=None, border_visible=False, border_colour='black', border_style='solid', border_width=1, border_radius=0, padding='0.2cm', margin=0, preview_box_style=None, preview_border_visible=True, preview_border_colour='black', preview_border_style='solid', preview_border_width=1, preview_border_radius=1, preview_padding=0, preview_margin=0, font_family='', font_size=None, font_style='', font_weight='')[source]

Function that defines the styling of the widget.

Parameters:
  • box_style (str or None (see below), optional) –

    Possible widget style options:

    'success', 'info', 'warning', 'danger', '', None
    
  • border_visible (bool, optional) – Defines whether to draw the border line around the widget.
  • border_colour (str, optional) – The colour of the border around the widget.
  • border_style (str, optional) – The line style of the border around the widget.
  • border_width (float, optional) – The line width of the border around the widget.
  • border_radius (float, optional) – The radius of the border around the widget.
  • padding (float, optional) – The padding around the widget.
  • margin (float, optional) – The margin around the widget.
  • preview_box_style (str or None (see below), optional) –

    Possible tab widgets style options:

    'success', 'info', 'warning', 'danger', '', None
    
  • preview_border_visible (bool, optional) – Defines whether to draw the border line around the preview.
  • preview_border_colour (str, optional) – The color of the border around the preview.
  • preview_border_style (str, optional) – The line style of the border around the preview.
  • preview_border_width (float, optional) – The line width of the border around the preview.
  • preview_border_radius (float, optional) – The radius of the corners of the box of the preview.
  • preview_padding (float, optional) – The padding around the preview box.
  • preview_margin (float, optional) – The margin around the preview box.
  • font_family (str (see below), optional) –

    The font family to be used. Example options:

    'serif', 'sans-serif', 'cursive', 'fantasy', 'monospace',
    'helvetica'
    
  • font_size (int, optional) – The font size.
  • font_style (str (see below), optional) –

    The font style. Example options:

    'normal', 'italic', 'oblique'
    
  • font_weight (See Below, optional) –

    The font weight. Example options:

    'ultralight', 'light', 'normal', 'regular', 'book', 'medium',
    'roman', 'semibold', 'demibold', 'demi', 'bold', 'heavy',
    'extra bold', 'black'
    
trait_names(**metadata)

Get a list of all the names of this class’ traits.

traits(**metadata)

Get a dict of all the traits of this class. The dictionary is keyed on the name and the values are the TraitType objects.

The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.

The metadata kwargs allow functions to be passed in which filter traits based on metadata values. The functions should take a single value as an argument and return a boolean. If any function returns False, then the trait is not included in the output. If a metadata key doesn’t exist, None will be passed to the function.

unobserve(handler, names=traitlets.All, type='change')

Remove a trait change handler.

This is used to unregister handlers to trait change notificiations.

Parameters:
  • handler (callable) – The callable called when a trait attribute changes.
  • names (list, str, All (default: All)) – The names of the traits for which the specified handler should be uninstalled. If names is All, the specified handler is uninstalled from the list of notifiers corresponding to all changes.
  • type (str or All (default: 'change')) – The type of notification to filter by. If All, the specified handler is uninstalled from the list of notifiers corresponding to all types.
unobserve_all(name=traitlets.All)

Remove trait change handlers of any type for the specified name. If name is not specified, removes all trait notifiers.