p5.OffscreenCanvas

A library for manipulating OffscreenCanvas with p5

Usage

Download the p5.OffscreenCanvas.js file in dist folder and put it in your project.

Important it should be loaded after p5, your index.html file should look something like this

...
<script src="path/to/p5"></script>
<script src="path/to/p5.OffscreenCanvas"></script>
<script src="path/to/sketch"></script>
...

This little wrapper provides a new function createOffscreenCanvas, which return a p5.Graphics-like object. It can be used to draw things off screen with the OffscreenCanvas Object instead of creating a new canvas in the dom tree. The OffscreenCanvas object can be also use in worker thread. This library also overwrite the image function for the 2D renderer to allow it to display ImageBitmap and OffscreenCanvas object.

See files in the example folder for more information.

Worker template

There is also a template for using this library with worker (worker-templ.js) in dist folder. You can use it to start your project with web worker. You can find more about how to do it in the code comments.

API

createOffscreenCanvas

Type: function

Arguments: width, height, [renderer = P2D]

Create a new wrapper object (of class OC) of a OffscreenCanvas object with the given width and height.

OC.reset

Type: function

Argument: none

Reset the offscreen canvas context matrix.

OC.remove

Type: function

Argument: none

Remove this offscreen canvas from the p5 instance.

OC.currentFrame

Type: function

Argument: none

Return: a ImageBitmap object

Return a bitmap image of the current render of the offscreen render this action will transfer all content in the canvas to the ImageBitmap object.

OC.currentBlob

Type: function

Arguments:

{object} options: an object containing the options, see https://developer.mozilla.org/en-US/docs/Web/API/OffscreenCanvas/convertToBlob

{function} callback: an callback to handle the promise

Return: A Promise returning a Blob object if a callback is not specified, else undefined.

Create a Blob object representing the image contained in the canvas

OC.currentCanvas

Type: function

Argument: none

Return: The OffscreenCanvas Object

Return the transferable OffscreenCanvas object.

OC.loadCanvas

Type: function

Argument:

{OffscreenCanvas} comingCanvas

Load a transferable OffscreenCanvas object. This action will create a new renderer if the loaded canvas' drawing context is different from the current one. Else the drawing context properties (e.g. fill and stroke color in 2d context) are also loaded. This action will not copy the OffscreenCanvas object.