# CheckBox

    __init__(
        self,
        master,
        text="",
        command=None,
        grid=None,
        align=None,
        args=None,
        visible=True,
        enabled=None,
        width=None,
        height=None)

### What is it?

The `CheckBox` object displays a check box to allow an option to be ticked or un-ticked.

### How do I make one?

Create a `CheckBox` object like this:

    from guizero import App, CheckBox
    app = App()
    checkbox = CheckBox(app, text="Add extra glitter")
    app.display()

### Starting parameters

When you create a `CheckBox` object you must specify `master` and `text` and you can specify any of the optional parameters. Specify parameters in the brackets, like this: `checkbox = CheckBox(app, text="Add extra glitter")`

Parameter | Takes | Default | Compulsory | Description
--- | --- | --- | --- | ---
master | App, Window or Box | - | Yes | The container to which this widget belongs
text | string | "" | No | The text to display next to the check box
align | string | None | - | Alignment of this widget within its container. Possible values: `"top"`, `"bottom"`, `"left"`, `"right"`.
command | function name | None | - | The name of a function to call when this checkbox is ticked/unticked
args | list | None | - | If you wish to pass any arguments to the function specified in the command parameter, you can specify them as a list
grid | List [int, int] | None | - | `[x,y]` coordinates of this widget. This parameter is only required if the `master` object has a grid layout.
visible | boolean | True | No | If the widget should be visible.
enabled | boolean | None | No | If the widget should be enabled. If `None` (the default) the enabled property will be inherited from the master
width | size | None | No | Set the width of the widget in characters or to `"fill"`
height | size | None | No | Set the height of the widget in characters or to `"fill"`

### Methods

You can call the following methods on a `CheckBox` object.

Method | Takes | Returns | Description
--- | --- | --- | ---
after(time, command, args=None) | time (int), command (function name), args (list of arguments) | - | Schedules a single call to `command` after `time` milliseconds. (To repeatedly call the same command, use `repeat()`)
cancel(command) | command (function name) | - | Cancels a scheduled call to `command`
destroy() | - | - | Destroys the widget
disable() | - | - | Disables the widget so that it is "greyed out" and cannot be interacted with
enable() | - | - | Enables the widget
focus() | - | - | Gives focus to the widget
hide() | - | - | Hides the widget from view. This method will unpack the widget from the layout manager.
repeat(time, command, args=None) | time (int), command (function name), args (list of arguments) | - | Repeats `command` every `time` milliseconds. This is useful for scheduling a function to be regularly called, for example updating a value read from a sensor.
resize(width, height) | width (int), height (int) | - | Sets the width and height of the widget
show() | - | - | Displays the widget if it was previously hidden
toggle() | - | - | Switches the `CheckBox` to the opposite of its current value. i.e. if it is ticked, untick it and vice versa
update_command(command, args =None) | command (function name), args (Optional List of arguments to be passed to command) | - | Updates the function to call when the checkbox is ticked/unticked

### Properties

You can set and get the following properties:

Method | Data type | Description
--- | --- | ---
align | string | The alignment of this widget within its container
bg | color | The background colour of the widget
enabled | boolean | `True` if the widget is enabled
font | string | The font of the text
grid | List | `[x,y]` coordinates of this widget. This parameter is only required if the `master` object has a grid
height | size | Set the height of the widget in characters or to `"fill"`
master | App or Box | The container to which this widget belongs
text | string | The text associated with the checkbox
value | int | `1` if the CheckBox is ticked or `0` if it is not ticked
visible | boolean | If this widget is visible
width | size | Set the width of the widget in characters or to `"fill"`
text_size | int | The size of the text
text_color | color | The colour of the text
tk | tkinter.Checkbutton | The internal tkinter object, see Using tkinter

Refer to a property as `<name of widget>.property`. For example, if your `CheckBox` object is called `checkbox` you would write `checkbox.value`.

You can set the property (for example `checkbox.value = 1`) or get the value of the property to use (for example `print(checkbox.value)`).

### Examples

Creating multiple CheckBoxes

Create multiple CheckBoxes like this.

    from guizero import App, CheckBox
    app = App()
    glitter = CheckBox(app, text="Add glitter")
    sparkles = CheckBox(app, text="Add sparkles")
    app.display()

Calling a function when a CheckBox value changes

You can call a function when the value of a CheckBox changes (becomes checked or unchecked). In this particular example all three CheckBoxes call the same function, but it is possible for each CheckBox object to call a different function.

    from guizero import App, Text, CheckBox, TextBox
    def calculate_extras():
        total = 0
        if syrup.value == 1:
            total += 20
        if sprinkles.value == 1:
            total += 10
        if cream.value == 1:
            total += 50
        cost.value = total

    app = App()

    questions = Text(app, text="What would you like with your coffee?")

    syrup = CheckBox(app, text="Caramel syrup (20p)", command=calculate_extras)
    sprinkles = CheckBox(app, text="Chocolate sprinkles (10p)", command=calculate_extras)
    cream = CheckBox(app, text="Whipped cream (50p)", command=calculate_extras)

    cost_of_extras = Text(app, text="Cost of extras:")
    cost = TextBox(app, text="0")

    app.display()