Embed

Embedding is a simple way to include the app in your website. Add the following code to your website:

<iframe
  id="butterfly"
  src="https://web.butterfly.linwood.dev/embed"
  width="100%"
  height="500px"
  allowtransparency="true"
></iframe>

Options

Option	Tip	Default	Opis
save	Boolean (true, false)	true	Enable save. If disabled, only an exit button will be shown
editable	Boolean (true, false)	true	Enable editing. If disabled, the document will be read-only
language	String (…, system, user)	user	Language of the document. If system, the language will be detected from the browser. If user, the language will set to the users preference
fileName	String		Display this file name in the embed title. It is visual only and does not change the document metadata

Messaging

The embed uses browser postMessage events. Send messages to the iframe with iframe.contentWindow.postMessage({ type, message }, origin). Butterfly sends messages back to the parent window with the same shape: { type: string, message?: unknown }.

See the embedding example for a live page that sends messages to the iframe and listens for messages from it.

<iframe
  id="butterfly"
  src="https://web.butterfly.linwood.dev/embed?save=true&editable=true&fileName=Example.bfly"
  width="100%"
  height="500"
></iframe>

<script>
  const butterflyOrigin = 'https://web.butterfly.linwood.dev';
  const butterfly = document.querySelector('#butterfly');

  function sendToButterfly(type, message) {
    butterfly.contentWindow.postMessage({ type, message }, butterflyOrigin);
  }

  window.addEventListener('message', (event) => {
    if (
      event.origin !== butterflyOrigin ||
      event.source !== butterfly.contentWindow
    ) {
      return;
    }

    const { type, message } = event.data ?? {};

    if (type === 'save') {
      const documentBytes = Array.from(message);
      console.log('Save requested by the embed', documentBytes);
    }

    if (type === 'exit') {
      const documentBytes = Array.from(message);
      console.log('Exit requested by the embed', documentBytes);
    }

    if (type === 'change') {
      console.log('Document changed', message);
    }

    if (type === 'getData') {
      console.log('Current document bytes', message);
    }

    if (type === 'render') {
      const image = new Image();
      image.src = `data:image/png;base64,${message}`;
      document.body.append(image);
    }

    if (type === 'renderSVG') {
      const preview = document.createElement('div');
      preview.innerHTML = message;
      document.body.append(preview);
    }
  });

  butterfly.addEventListener('load', () => {
    sendToButterfly('getData');

    // Omit camera and size fields to render the current visible canvas view.
    sendToButterfly('render', {
      renderBackground: true,
    });

    // Set the camera explicitly to render from the document origin instead.
    sendToButterfly('render', {
      x: 0,
      y: 0,
      width: 600,
      height: 400,
      scale: 1,
      rotation: 0,
      padding: { top: 0, right: 0, bottom: 0, left: 0 },
      renderBackground: true,
    });
  });
</script>

To load document bytes into the embed, send an array of byte values:

sendToButterfly('setData', documentBytes);

Events

Listen for events with window.addEventListener('message', ...).

save

The save event is emitted when the user clicks the save button.

Parameters:

• message (Type List<int>): The data of the document.

exit

The exit event is emitted when the user clicks the exit button.

Parameters:

• message (Type List<int>): The data of the document.

change

The change event is emitted when the user changes the document.

Parameters:

• message (Type List<int>): The data of the document.

Methods

Call methods with iframe.contentWindow.postMessage(...). Methods that return data send another message back with the same type.

getData

The getData method returns the data of the document.

No parameters. Returns: List<int>

setData

The setData method sets the data of the document.

Parameters:

• data (Type List<int>): The data of the document.

render

The render method renders the document to a png image.

All parameters are optional. With no camera or size parameters, Butterfly exports the current visible canvas view. To export from the document origin, set x: 0, y: 0, scale: 1, and rotation: 0 together with the desired output size.

Padding expands the output dimensions: the final width is width + left + right and the final height is height + top + bottom.

Parameters:

Parameter	Tip	Default	Opis
x	Number	Current view x	Document x position of the exported view.
y	Number	Current view y	Document y position of the exported view.
width	Number	Current viewport width	Output width in pixels.
height	Number	Current viewport height	Output height in pixels.
scale	Number	Current zoom	Camera zoom used for the export.
rotation	Number	Current rotation	Camera rotation in radians.
padding	Object	All sides 0	Extra output pixels added with top, right, bottom, and left fields.
renderBackground	Boolean	true	Whether to include the document background.

Returns: String (Base64 encoded image)

renderSVG

The renderSVG method renders the document to a svg image.

It accepts the same optional view parameters as render. Omitting them exports the current visible canvas view; explicitly setting an identity camera exports from the document origin.

Parameters:

Parameter	Tip	Default	Opis
x	Number	Current view x	Document x position of the exported view.
y	Number	Current view y	Document y position of the exported view.
width	Number	Current viewport width	Output width in pixels.
height	Number	Current viewport height	Output height in pixels.
scale	Number	Current zoom	Camera zoom used for the export.
rotation	Number	Current rotation	Camera rotation in radians.
padding	Object	All sides 0	Extra output pixels added with top, right, bottom, and left fields.
renderBackground	Boolean	true	Whether to include the document background.

Returns: String (SVG)