Add a button to a graph

A button is a small scene that is pretty much just some text drawn over a rounded rectangle. The button scene contains logic to detect when the button is pressed, tracks it as the pointer moves around, and when it is released.

Data

title

• title - a bitstring describing the text to show in the button

Messages

If a button press is successful, it sends an event message to the host scene in the form of:

{:click, id}

These messages can be received and handled in your scene via Scenic.Scene.filter_event/3. For example:

...

@impl Scenic.Scene
def init(_, _opts) do
  graph =
    Graph.build()
    |> Scenic.Components.button("Sample Button", id: :sample_btn_id, t: {10, 10})

  state = %{}

  {:ok, state, push: graph}
end

@impl Scenic.Scene
def filter_event({:click, :sample_btn_id}, _from, state) do
  IO.puts("Sample button was clicked!")
  {:cont, event, state}
end

Styles

Buttons honor the following standard styles

• :hidden - If false the component is rendered. If true, it is skipped. The default is false.
• :theme - The color set used to draw. See below. The default is :primary

Additional Styles

Buttons honor the following list of additional styles.

• :width - :auto (default) or pass in a number to set the width of the button
• :height - :auto (default) or pass in a number to set the height of the button.
• :radius - pass in a number to set the radius of the button's rounded rectangle.
• :alignment - set the alignment of the text inside the button. Can be one of :left, :right, :center. The default is :center.
• :button_font_size - the size of the font in the button

Buttons do not use the inherited :font_size style as they should look consistent regardless of what size the surrounding text is.

Theme

Buttons work well with the following predefined themes: :primary, :secondary, :success, :danger, :warning, :info, :text, :light, :dark

To pass in a custom theme, supply a map with at least the following entries:

• :text - the color of the text in the button
• :background - the normal background of the button
• :active - the background while the button is pressed

Usage

You should add/modify components via the helper functions in Scenic.Components

Examples

The following example creates a simple button and positions it on the screen.

graph
|> button("Example", id: :button_id, translate: {20, 20})

The next example makes the same button as before, but colors it as a warning button. See the options list above for more details.

graph
|> button("Example", id: :button_id, translate: {20, 20}, theme: :warning)