Animations

Something the plugin draws as a loop runs counts as an animation of the project.

The animation window plays it, and every export of the animation (a GIF, a video, a sprite sheet, a plugin's own kind of file) writes it.

animations: [{
  key: 'pulse', name: 'Pulse',
  frames: (doc) => (doc.pulse ? doc.pulse_frames ?? 12 : 0),      // 0 or 1: this project is not moved by it
  resize: (doc, frames) => void (doc.pulse_frames = frames),
  draw(doc, at) {
    const canvas = document.createElement('canvas');
    canvas.width = at.w;
    canvas.height = at.h;
    const pen = canvas.getContext('2d')!;
    pen.globalAlpha = 0.5 + 0.5 * Math.sin(at.t * Math.PI * 2);
    pen.fillStyle = '#ffffff';
    pen.fillRect(0, 0, at.w, at.h);
    return canvas;
  },
}],

import math

from rassam import canvas


def frames(doc):
    return doc.get('pulse_frames', 12) if doc.get('pulse') else 0      # 0 or 1: this project is not moved by it


def resize(doc, count):
    doc['pulse_frames'] = count


@plugin.animation('Pulse', frames=frames, resize=resize)
def pulse(doc, at):
    sheet = canvas(at.w, at.h)
    pen = sheet.getContext('2d')
    pen.globalAlpha = 0.5 + 0.5 * math.sin(at.t * math.tau)
    pen.fillStyle = '#ffffff'
    pen.fillRect(0, 0, at.w, at.h)
    return sheet

Key	What it does
`frames(doc)`	How many frames the loop has in a project. A picture with frames of its own keeps its own count; one without takes yours.
`draw(doc, at)`	The picture at a moment of the loop. `at.t` runs from 0 to 1, `at.frame` is the frame's number, `at.w` and `at.h` the picture's size, `at.layer(id)` a layer as it is drawn.
`resize(doc, frames)`	Lets the animation window set the number of frames.
`name`	Labels the loop in the animation window.

What `draw` gives

A canvas: laid over the whole image.
{ canvas, layer }: the canvas stands in for that layer, in its place among the others.
An array of those, for several at once. Or nothing.

In Python, canvas(width, height) from rassam makes a new picture to draw on, the layer form is a dict ({'canvas': sheet, 'layer': id}), and frames may be a plain number when it does not depend on the project.

Animations

What draw gives

What `draw` gives