Module: JekyllAutoThumbnails::Scanner

Defined in:
lib/jekyll-auto-thumbnails/scanner.rb

Overview

HTML scanning for images

Class Method Summary collapse

Class Method Details

.calculate_dimensions(url, width, height, site_source) ⇒ Array<Integer, Integer>

Calculate missing dimension based on aspect ratio

Parameters:

  • url (String) —

    image URL

  • width (Integer, nil) —

    specified width

  • height (Integer, nil) —

    specified height

  • site_source (String) —

    site source directory

Returns:

  • (Array<Integer, Integer>) —

    [width, height] with calculated dimension



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 92

def self.calculate_dimensions(url, width, height, site_source)
  file_path = UrlResolver.to_filesystem_path(url, site_source)
  return [width, height] unless file_path && File.exist?(file_path)

  actual_width, actual_height = image_dimensions(file_path)
  return [width, height] unless actual_height

  # Calculate missing dimension preserving aspect ratio
  if width && !height
    # Width specified, calculate height
    aspect_ratio = actual_height.to_f / actual_width
    height = (width * aspect_ratio).round
  elsif height && !width
    # Height specified, calculate width
    aspect_ratio = actual_width.to_f / actual_height
    width = (height * aspect_ratio).round
  end

  [width, height]
end

.check_and_register_oversized(url, registry, config, site_source) ⇒ Object

Check if image exceeds max dimensions and register if so

Parameters:

  • url (String) —

    image URL

  • registry (Registry) —

    image registry

  • config (Configuration) —

    configuration

  • site_source (String) —

    site source directory



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 51

def self.check_and_register_oversized(url, registry, config, site_source)
  file_path = UrlResolver.to_filesystem_path(url, site_source)
  return unless file_path && File.exist?(file_path)

  actual_width, actual_height = image_dimensions(file_path)
  return unless actual_height

  # Check if exceeds max dimensions
  exceeds_width = config.max_width && actual_width > config.max_width
  exceeds_height = config.max_height && actual_height > config.max_height

  return unless exceeds_width || exceeds_height

  # Register with max dimensions (preserving aspect ratio logic in Generator)
  registry.register(url, config.max_width, config.max_height)
end

.dimensions_match_original?(url, width, height, site_source) ⇒ Boolean

Check if requested dimensions match original dimensions

Parameters:

  • url (String) —

    image URL

  • width (Integer) —

    requested width

  • height (Integer) —

    requested height

  • site_source (String) —

    site source directory

Returns:

  • (Boolean) —

    true if dimensions match original



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 132

def self.dimensions_match_original?(url, width, height, site_source)
  file_path = UrlResolver.to_filesystem_path(url, site_source)
  return false unless file_path && File.exist?(file_path)

  actual_width, actual_height = image_dimensions(file_path)

  width == actual_width && height == actual_height
end

.image_dimensions(file_path) ⇒ Array<Integer, Integer>?

Get image dimensions from file

Parameters:

  • file_path (String) —

    path to image file

Returns:

  • (Array<Integer, Integer>, nil) —

    [width, height] or nil



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 72

def self.image_dimensions(file_path)
  # Use ImageMagick identify command (shell-free, cross-platform)
  # Use [0] to get only first frame (important for animated GIFs)
  # Wrapper handles both ImageMagick v6 and v7
  output, status = ImageMagickWrapper.execute_identify("-format", "%wx%h", "#{file_path}[0]")
  return nil unless status.success?

  match = output.match(/\A\s*(\d+)x(\d+)\s*\z/)
  [Integer(match[1]), Integer(match[2])]
rescue StandardError
  nil
end

.parse_dimension(value) ⇒ Integer?

Parse dimension attribute (width or height)

Parameters:

  • value (String, nil) —

    attribute value

Returns:

  • (Integer, nil) —

    parsed integer or nil



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 117

def self.parse_dimension(value)
  # Strip non-numeric characters (e.g., "300px" -> 300)
  numeric = value.to_s.gsub(/[^\d]/, "")
  return nil if numeric.empty?

  Integer(numeric)
end

.scan_html(html, registry, config, site_source = nil) ⇒ Object

Scan HTML for images needing optimization

Parameters:

  • html (String) —

    HTML content

  • registry (Registry) —

    image registry

  • config (Configuration) —

    configuration

  • site_source (String) (defaults to: nil) —

    Jekyll site source (optional, for unsized image checking)



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# File 'lib/jekyll-auto-thumbnails/scanner.rb', line 17

def self.scan_html(html, registry, config, site_source = nil)
  doc = HtmlParser.parse(html, config.parser)

  # Only process images in <article> tags
  doc.css("article img").each do |img|
    src = img["src"]
    next unless src
    next if UrlResolver.external?(src)

    # Check for explicit dimensions
    width = parse_dimension(img["width"])
    height = parse_dimension(img["height"])

    if width || height
      # Only identify for aspect-ratio fill when a dimension is missing
      width, height = calculate_dimensions(src, width, height, site_source) if site_source && (!width || !height)

      # Skip if dimensions match original (no thumbnail needed)
      next if site_source && dimensions_match_original?(src, width, height, site_source)

      registry.register(src, width, height)
    elsif site_source && (config.max_width || config.max_height)
      # Unsized but max config exists - check actual dimensions
      check_and_register_oversized(src, registry, config, site_source)
    end
  end
end