Extension contracts

These contracts are public for integrations. Application code normally starts with Image and uses the built-in implementations.

Drivers

DriverInterface reports its name, capabilities, support for a concrete operation, decode support for a format, encode support for an Encoding, and processes a negotiated Plan.

Built-in drivers are GdDriver and ImagickDriver. See Writing a driver for the implementation contract and conformance suite.

Operations

An executable operation implements OperationInterface. A portable operation also implements PortableOperationInterface, which provides projection, parsing, and stable serialization. Geometry operations may implement Solvable and return a resolved Placement.

The built-in operation classes are Adjust, Blur, Crop, Escape, Extend, Flatten, Flip, Grayscale, IccConvert, Invert, Orient, Overlay, Pixelate, Resize, Rotate, Sharpen, Tint, and Trim.

Apply custom operations with apply(). Use escape() only for trusted, driver-specific code. Supply a stable identity when its output affects cache keys.

Portable operations can be serialized for URLs or stored configuration:

<?php

use Alto\Image\Image;
use Alto\Image\Transform;

$transform = Transform::parse('cover=1280x720,g:top-right|sharpen');
$image = Image::open('photo.jpg')->transformedBy($transform);

Parse untrusted strings with Transform::parse($value, only: [...]). Exclude overlay unless its paths are also constrained.

Stores

StoreInterface defines deterministic path lookup, existence checks, one and many output writes, and pruning. The built-in implementations are LocalStore and FlysystemStore.

See Storage for usage and backend behavior.

Analyzers

AnalyzerInterface<TResult> receives a bounded Raster and returns an application-defined result. Built-in analyzers are DominantColors and PerceptualHash.

See Image analysis.

Driver testing toolkit

The Alto\Image\Test namespace is supported public API for third-party drivers:

• ArrayDriver
• Corpus
• DriverTestCase
• ImageAssertions

Extend DriverTestCase to apply the same behavioral contract used by the built-in drivers.