Resizing Images

The resizeImage function resizes and re-encodes a retained image through an admitted native image-transform provider. Its Rust codec stack performs the conversion without a Node/Sharp runtime or separate image CLI. The provider still needs a configured binding and artifact storage. Both input and output filenames are relative to the sandbox virtual filesystem.

Use it to shrink large generated images before embedding them in ebooks/PDFs, or before publishing them to the web.

Signature

resizeImage(
  inputFile: string,       // VFS path to the source image
  outputFile: string,      // VFS path for the resized image
  maxWidth?: number,       // Cap width in px (0 = no cap)
  maxHeight?: number,      // Cap height in px (0 = no cap)
  quality?: number,        // Lossy quality 1-100 for jpeg/webp/avif (default: 85)
  format?: "jpeg" | "png" | "webp" | "avif" // Output format
                           //   (default: inferred from outputFile extension)
) -> file

Images are only ever scaled down — a source smaller than the cap is left at its natural size. The output format is honored exactly: it comes from the explicit format parameter, or is inferred from the outputFile extension.

Example

let webHero = resizeImage(
  inputFile: "photos/hero.png",
  outputFile: "photos/hero-web.jpg",
  maxWidth: 1600,
  maxHeight: 0,        // no height cap; preserve aspect ratio
  quality: 82
)

Host Setup

Configure the renderer and grant the session access before running these examples. See the rendering overview for dependencies and the Tool Server guide for host setup.