philiprehberger-image_size

Image dimension detection from file headers without full decode.

Requirements

Ruby >= 3.1

Installation

Add to your Gemfile:

gem "philiprehberger-image_size"

Or install directly:

gem install philiprehberger-image_size

Usage

Basic Detection

require "philiprehberger/image_size"

info = Philiprehberger::ImageSize.of("photo.png")
info.width   # => 1920
info.height  # => 1080
info.format  # => :png

Dimensions Only

width, height = Philiprehberger::ImageSize.dimensions("banner.jpg")

Format Detection

format = Philiprehberger::ImageSize.format("image.webp")
# => :webp

IO Objects

File.open("photo.gif", "rb") do |f|
  info = Philiprehberger::ImageSize.of(f)
  puts info.to_s  # => "GIF 320x240"
end

Animation Detection

info = Philiprehberger::ImageSize.of("animation.gif")
info.animated?  # => true

Alpha Channel Detection

info = Philiprehberger::ImageSize.of("transparent.png")
info.alpha?  # => true

EXIF Orientation

info = Philiprehberger::ImageSize.of("rotated.jpg")
info.orientation  # => 6
# Width and height reflect actual display dimensions (swapped for 90/270 rotation)

ImageInfo Value Object

info = Philiprehberger::ImageSize.of("photo.bmp")
info.to_a  # => [640, 480]
info.to_h  # => { width: 640, height: 480, format: :bmp, animated: false, alpha: false, orientation: nil }

API

`Philiprehberger::ImageSize`

Method	Description
`.of(path_or_io)`	Returns `ImageInfo` with width, height, format, and metadata
`.dimensions(path_or_io)`	Returns `[width, height]` array
`.format(path_or_io)`	Returns format symbol (`:png`, `:jpeg`, `:gif`, `:bmp`, `:webp`, `:tiff`, `:ico`, `:cur`, `:svg`, `:avif`)

`Philiprehberger::ImageSize::ImageInfo`

Method	Description
`#width`	Image width in pixels (display dimensions for rotated JPEG)
`#height`	Image height in pixels (display dimensions for rotated JPEG)
`#format`	Format symbol
`#animated?`	Whether the image is animated (GIF, WebP, APNG)
`#alpha?`	Whether the image has an alpha channel
`#orientation`	EXIF orientation (1-8), nil if not applicable
`#to_a`	Returns `[width, height]`
`#to_h`	Returns hash with all attributes
`#to_s`	Returns `"FORMAT WxH"` string

Development

bundle install
bundle exec rspec
bundle exec rubocop

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License

MIT