imageresize

Documentation

Overview

Package imageresize shrinks inline images to fit the provider request-size limits, mirroring the upstream coding-agent image-resize behaviour with a stdlib-only implementation (PNG/JPEG/GIF decode, area-averaging downscale, PNG/JPEG re-encode). It is depended on by both the @file CLI path and the read tool, and intentionally lives in its own leaf package so packages/ai stays at the bottom of the dependency DAG.

Index

• func DimensionNote(r *Result) string
• type Options
• type Result
  • func Resize(input []byte, mimeType string, opts Options) *Result

Functions

func DimensionNote

func DimensionNote(r *Result) string

DimensionNote returns the note that maps resized-image coordinates back to the original, or "" when the image was not resized. It mirrors the upstream formatDimensionNote string exactly.

Types

type Options

type Options struct {
	MaxWidth    int // default 2000
	MaxHeight   int // default 2000
	MaxBytes    int // default 4.5MB of base64 payload (below Anthropic's 5MB limit)
	JPEGQuality int // default 80
}

Options controls Resize. Zero fields fall back to the defaults that mirror the upstream image-resize-core defaults.

type Result

type Result struct {
	Data           string
	MimeType       string
	OriginalWidth  int
	OriginalHeight int
	Width          int
	Height         int
	WasResized     bool
}

Result is the outcome of Resize: base64 data plus the dimensions before/after, mirroring the upstream ResizedImage shape.

func Resize

func Resize(input []byte, mimeType string, opts Options) *Result

Resize shrinks an image to fit within the configured max dimensions and base64 payload size, returning nil when it cannot be brought under MaxBytes. It is a stdlib port of the upstream resizeImageInProcess: try the original if it already fits, otherwise downscale to the max box and pick the smallest of PNG / decreasing-quality JPEG, progressively reducing dimensions if needed.

Inputs whose format the standard library cannot decode (e.g. WebP) are passed through unchanged when already under MaxBytes, or omitted (nil) when not.