Module: Jekyll::ResponsiveMagickFilter

Defined in:
lib/jekyll-responsive-magick.rb

Constant Summary collapse

@@sizes = 
{}

Instance Method Summary collapse

Instance Method Details

#check_path(input, filter_name) ⇒ Object

Throw error if it is not an absolute path



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# File 'lib/jekyll-responsive-magick.rb', line 46

def check_path(input, filter_name)
  if not input.is_a? String || input.length == 0 || input.chr != '/'
    throw "#{filter_name}: path must be an absolute path"
  end
end

#check_size(input, from) ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 138

def check_size(input, from)
  check_path(input, from)
  if not @@sizes[input]
    identify(input)
  end
end

#convert(src, src_extname, dst, width) ⇒ Object

Convert an image from src to dst with the given width



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# File 'lib/jekyll-responsive-magick.rb', line 69

def convert(src, src_extname, dst, width)
  site = @context.registers[:site]      
  quality = site.config['responsive']['quality'] || 80
  verbose = site.config['responsive']['verbose'] || false

  if File.exist?(dst) and File.mtime(src) < File.mtime(dst)
    return
  end

  FileUtils.mkdir_p(File.dirname(dst))
  cmd = "convert #{src_extname == '.apng' ? 'apng:' : ''}#{src.shellescape} -strip -quality #{quality} -resize #{width} #{dst.shellescape}"
  
  if verbose
    print("#{cmd}\n")
  end
  
  if not system(cmd)
    throw "srcset: failed to execute 'convert', is ImageMagick installed?"
  end
end

#height(input, from = "height") ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 133

def height(input, from = "height")
  check_size(input, from)
  return @@sizes[input][1]
end

#identify(input) ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 27

def identify(input)
  site = @context.registers[:site]
  if site.config['responsive']['verbose']
    verbose = site.config['responsive']['verbose']
  else
    verbose = false
  end
  cmd = "identify -ping -format '%w,%h' .#{input.shellescape}"
  if verbose
    print("#{cmd}\n")
  end
  sizes = `#{cmd}`
  if not $?.success?
    throw "width/height: failed to execute 'identity', is ImageMagick installed?"
  end
  @@sizes[input] = sizes.split(',', 2).map!(&:to_i)
end

#is_image?(src) ⇒ Boolean

Return true if the file exists and is an image mime type



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# File 'lib/jekyll-responsive-magick.rb', line 53

def is_image?(src)
  cmd = "identify -ping #{src.shellescape} 2>&1"
  output = `#{cmd}`

  if not $?.success?
    if output.include?("identify: improper image header")
      throw "file is not an image: '#{src}'"
    else
      throw "width/height: failed to execute 'identity', is ImageMagick installed?"
    end
  end

  return true
end

#size(input, width) ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 145

def size(input, width)
  check_path(input, "size")
  site = @context.registers[:site]
  dirname = File.dirname(input)
  basename = File.basename(input, '.*')
  extname = File.extname(input)
  new_extname = site.config['responsive']['format'] ? ".#{site.config['responsive']['format']}" : extname
  src = ".#{dirname}/#{basename}#{extname}"

  if not File.exist?(src) or not is_image?(src)
    throw "srcset: file does not exist or is not an image: '#{src}'"
  end
  
  file = "#{basename}-#{width}w#{new_extname}"
  dst = "_responsive#{dirname}/#{file}"
  full_path = "#{dirname}/#{file}"

  if site.static_files.find{|file| file.path == dst}
    return full_path # image is already generated
  end

  site.static_files << StaticFile.new(site, "_responsive", dirname, file)
  convert(src, extname, dst, width)

  return full_path
end

#srcset(input) ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 90

def srcset(input)
  check_path(input, "srcset")
  site = @context.registers[:site]
  dirname = File.dirname(input)
  basename = File.basename(input, '.*')
  extname = File.extname(input)
  new_extname = site.config['responsive']['format'] ? ".#{site.config['responsive']['format']}" : extname
  src = ".#{dirname}/#{basename}#{extname}"
  srcwidth = width(input, "srcset")      
  srcset = ["#{input} #{srcwidth}w"]

  if not File.exist?(src) or not is_image?(src)
    throw "srcset: file does not exist or is not an image: '#{src}'"
  elsif File.extname(src) != '.svg'
    # as default, use breakpoints of Bootstrap 5
    widths = site.config['responsive']['widths'] || [576, 768, 992, 1200, 1400]
    
    widths.map do |width|
      if not srcwidth > width
        next # image is not large enough to generate a smaller version
      end

      file = "#{basename}-#{width}w#{new_extname}"
      dst = "_responsive#{dirname}/#{file}"
      srcset.push("#{dirname}/#{file} #{width}w")

      if site.static_files.find{|file| file.path == dst}
        next # image is already generated
      end
      
      site.static_files << StaticFile.new(site, "_responsive", dirname, file)
      convert(src, extname, dst, width)
    end
  end

  return srcset.join(', ')
end

#width(input, from = "width") ⇒ Object 



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# File 'lib/jekyll-responsive-magick.rb', line 128

def width(input, from = "width")
  check_size(input, from)
  return @@sizes[input][0]
end