Image.Plug.Capabilities (image_plug v0.1.0)

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Probes the local libvips build for optional encoder capabilities.

Run once at application boot. Results are cached in :persistent_term so per-request reads are free.

Currently probes AVIF, JP2, and TIFF write support. Adding a probe for another capability is one new clause in probe/0 and one new accessor.

Summary

Functions

avif_write?()

Returns whether the local libvips can encode AVIF.

jp2_write?()

Returns whether the local libvips can encode JPEG 2000 (JP2).

probe()

Performs every capability probe and caches the results.

tiff_write?()

Returns whether the local libvips can encode TIFF.

Functions

avif_write?()

@spec avif_write?() :: boolean()

Returns whether the local libvips can encode AVIF.

Falls back to a one-off probe if probe/0 (in this module) has not been called — useful in tests that exercise the encoder without booting the application.

Returns

  • true if libvips can write AVIF.

  • false otherwise.

Examples

iex> is_boolean(Image.Plug.Capabilities.avif_write?())
true

jp2_write?()

@spec jp2_write?() :: boolean()

Returns whether the local libvips can encode JPEG 2000 (JP2).

Required by IIIF Image API 3.0 Compliance Level 2 deployments that promise JP2 support. Available only when libvips was built with libopenjp2.

Returns

  • true if libvips can write JP2.

  • false otherwise.

probe()

@spec probe() :: :ok

Performs every capability probe and caches the results.

Idempotent: calling probe/0 twice in the same VM lifetime returns the same booleans without re-probing.

Returns

  • :ok.

tiff_write?()

@spec tiff_write?() :: boolean()

Returns whether the local libvips can encode TIFF.

Required by IIIF Image API 3.0 Compliance Level 2 deployments that promise TIFF support.

Returns

  • true if libvips can write TIFF.

  • false otherwise.