Module imaging 

Image processing — pure Rust, zero external dependencies.

This module handles all image manipulation in Simple Gal: reading dimensions, extracting IPTC metadata, generating responsive sizes, and creating thumbnails. Everything uses pure Rust crates (image, rav1e) — no ImageMagick, no FFmpeg, no system libraries. This is a deliberate choice: the binary is fully self-contained, so it works on any machine without installing prerequisites.

Operation Table

Operation	Implementation
Identify (dimensions)	image::image_dimensions
IPTC metadata	Custom parser (iptc_parser) — reads JPEG APP13 + TIFF IFD
Resize → AVIF	Lanczos3 resampling + rav1e AVIF encoder
Thumbnail	resize_to_fill (center crop) + optional unsharpen

Architecture: Backend Trait Pattern

The module separates what to do from how to do it using the ImageBackend trait:

• calculations — Pure functions for dimension math (aspect ratios, responsive sizes). Fully unit-testable with no I/O.
• params — Data structs (ResizeParams, ThumbnailParams) describing operations.
• backend — The ImageBackend trait defining identify/resize/thumbnail. Includes a MockBackend (behind #[cfg(test)]) for fast, deterministic tests.
• rust_backend — RustBackend, the production implementation using image + rav1e.
• operations — High-level functions (create_responsive_images, create_thumbnail) that combine calculations + backend. Accept &dyn ImageBackend for testability.

Re-exports

pub use backend::BackendError;

pub use backend::ImageBackend;

pub use calculations::calculate_thumbnail_dimensions;

pub use operations::ResponsiveConfig;

pub use operations::ThumbnailConfig;

pub use operations::create_responsive_images;

pub use operations::create_thumbnail;

pub use operations::get_dimensions;

pub use params::Quality;

pub use params::Sharpening;

pub use rust_backend::RustBackend;

pub use rust_backend::supported_input_extensions;

Modules

backend

Image processing backend trait and shared types.

calculations

Pure calculation functions for image dimensions.

operations

High-level image operations.

params

Parameter types for image operations.

rust_backend

Pure Rust image processing backend — zero external dependencies.