Interface RenderOptions

Number of pixels per grid ‘point’ (defaults to 1)

Background color to draw beneath transparent parts of the canvas

Number of samples used for antialiasing each pixel. 0 and 1 both mean one sample a pixel -- no multisampling.

Which page to export, numbered from 1.

Left out, a single-page format encodes the current page -- the most recently added one, which is what canvas.getContext() hands back -- and a format that gathers pages takes all of them. A negative number counts from the end, so -1 is that same current page named explicitly.

A number past either end is a RangeError that names the page asked for, not the index it resolved to.

Which pages to gather, numbered from 1 and inclusive at both ends.

Left out, a format that gathers pages takes all of them. Negative numbers count from the end, as RenderOptions.page does, so [2, -1] is everything after the first page.

This is what separates an intro from the loop that follows it: two calls over one canvas, each with its own loop, rather than one file that has to compromise between them.

const intro = await canvas.toBuffer('webp', { fps: 30, pageRange: [1, 20], loop: 1 })
const cycle = await canvas.toBuffer('webp', { fps: 30, pageRange: [21, 60], loop: 0 })
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It serves the paged documents as well -- { pageRange: [12, 18] } pulls one chapter out of a long PDF, and a filename template such as frame-{}.png writes only the frames named.

Naming both this and page is a TypeError: they answer the same question differently. A bound past either end is a RangeError naming the page asked for, an end before its start is a RangeError, and a range given to a format that encodes a single page -- with no filename template to write a sequence -- is a TypeError.