Class: NSWTopo::Chrome

Inherits:
Object
  • Object
show all
Defined in:
lib/nswtopo/chrome.rb

Defined Under Namespace

Classes: Error, Node

Constant Summary collapse

MIN_VERSION = 
112
TIMEOUT_KILL = 
5
TIMEOUT_LOADEVENT = 
30
TIMEOUT_COMMAND = 
10
TIMEOUT_SCREENSHOT = 
120
ARGS = 
%W[
  --disable-background-networking
  --disable-component-extensions-with-background-pages
  --disable-component-update
  --disable-default-apps
  --disable-extensions
  --disable-features=site-per-process,Translate
  --disable-lcd-text
  --disable-renderer-backgrounding
  --force-color-profile=srgb
  --force-device-scale-factor=1
  --headless=new
  --hide-scrollbars
  --no-default-browser-check
  --no-first-run
  --no-startup-window
  --remote-debugging-pipe=JSON
  --use-mock-keychain
]

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(url, width: 800, height: 600, background: { r: 0, g: 0, b: 0, a: 0 }, args: []) ⇒ Chrome

Returns a new instance of Chrome.



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# File 'lib/nswtopo/chrome.rb', line 107

def initialize(url, width: 800, height: 600, background: { r: 0, g: 0, b: 0, a: 0 }, args: [])
  @id, @data_dir = 0, Dir.mktmpdir("nswtopo_headless_chrome_")
  ObjectSpace.define_finalizer self, Chrome.rmdir(@data_dir)

  args << "--disable-gpu" if Config["gpu"] == false
  args << "--user-data-dir=#{@data_dir}"

  input, @input, @output, output = *IO.pipe, *IO.pipe
  input.nonblock, output.nonblock = false, false
  @input.sync = true

  @pid = Process.spawn Chrome.path, *ARGS, *args, 1 => File::NULL, 2 => File::NULL, 3 => input, 4 => output, :pgroup => Chrome.windows? ? nil : true
  ObjectSpace.define_finalizer self, Chrome.kill(@pid, @input, @output)
  input.close; output.close

  target_id = command("Target.createTarget", url: url).fetch("targetId")
  @session_id = command("Target.attachToTarget", targetId: target_id, flatten: true).fetch("sessionId")
  command "Page.enable"
  wait "Page.loadEventFired", timeout: TIMEOUT_LOADEVENT
  command "Emulation.setDeviceMetricsOverride", width: width, height: height, deviceScaleFactor: 1, mobile: false
  command "Emulation.setDefaultBackgroundColorOverride", color: background
  @node_id = command("DOM.getDocument").fetch("root").fetch("nodeId")
rescue SystemCallError
  raise Error, "couldn't start chrome"
rescue KeyError
  raise Error
end

Class Method Details

.kill(pid, *pipes) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 74

def self.kill(pid, *pipes)
  Proc.new do
    if windows?
      *, status = Open3.capture2e *%W[taskkill /f /t /pid #{pid}]
      Process.kill "KILL", pid unless status.success?
    else
      Timeout.timeout(TIMEOUT_KILL, Error) do
        Process.kill "-USR1", Process.getpgid(pid)
        Process.wait pid
      rescue Error
        Process.kill "-KILL", Process.getpgid(pid)
        Process.wait pid
      end
    end
  rescue Errno::ESRCH, Errno::ECHILD
  ensure
    pipes.each(&:close)
  end
end

.mac? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nswtopo/chrome.rb', line 35

def self.mac?
  /darwin/ === RbConfig::CONFIG["host_os"]
end

.path ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 43

def self.path
  @path ||= case
  when Config["chrome"]
    [Config["chrome"]]
  when mac?
    ["/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", "/Applications/Chromium.app/Contents/MacOS/Chromium"]
  when windows?
    ["C:/Program Files/Google/Chrome/Application/chrome.exe", "C:/Program Files (x86)/Google/Chrome/Application/chrome.exe"]
  else
    ENV["PATH"].split(File::PATH_SEPARATOR).product(%w[chrome google-chrome chromium chromium-browser]).map do |path, binary|
      [path, binary].join(File::SEPARATOR)
    end
  end.find do |path|
    File.executable?(path) && !File.directory?(path)
  end.tap do |path|
    raise Error, "couldn't find chrome" unless path
    stdout, status = Open3.capture2 path, "--version"
    raise Error, "couldn't start chrome" unless status.success?
    version = /(?<major>\d+)(?:\.\d+)*/.match stdout
    raise Error, "couldn't start chrome" unless version
    raise Error, "chrome version #{MIN_VERSION} or higher required" if version[:major].to_i < MIN_VERSION
  end
end

.rmdir(tmp) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 67

def self.rmdir(tmp)
  Proc.new do
    FileUtils.remove_entry tmp
  rescue SystemCallError
  end
end

.windows? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nswtopo/chrome.rb', line 39

def self.windows?
  /mingw|mswin|cygwin/ === RbConfig::CONFIG["host_os"]
end

.with_browser(url, **opts, &block) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 100

def self.with_browser(url, **opts, &block)
  browser = new url, **opts
  block.call browser
ensure
  browser&.close
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 94

def close
  Chrome.kill(@pid, @input, @output).call
  Chrome.rmdir(@data_dir).call
  ObjectSpace.undefine_finalizer self
end

#command(method, timeout: TIMEOUT_COMMAND, **params) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 162

def command(method, timeout: TIMEOUT_COMMAND, **params)
  send id: @id += 1, method: method, params: params
  Timeout.timeout(timeout) do
    messages.find do |message|
      message["id"] == @id
    end
  end.fetch("result")
rescue Timeout::Error, KeyError
  raise Error
end

#messages ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 140

def messages
  Enumerator.produce do
    json = @output.readline(?\0).chomp(?\0)
    JSON.parse(json).tap do |message|
      raise Error if message["error"]
      raise Error if message["method"] == "Target.detachedFromTarget"
    end
  rescue JSON::ParserError, EOFError
    raise Error
  end
end

#print_to_pdf(pdf_path, &block) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 180

def print_to_pdf(pdf_path, &block)
  data = command("Page.printToPDF", timeout: nil, preferCSSPageSize: true).fetch("data")
  pdf = Base64.decode64 data
  if defined? HexaPDF
    HexaPDF::Document.new(io: StringIO.new(pdf)).tap(&block).write(pdf_path.to_s)
  else
    pdf_path.binwrite(pdf)
  end
rescue KeyError
  raise Error
end

#query_selector(selector) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 228

def query_selector(selector)
  Node.new self, selector
end

#query_selector_node_id(selector) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 192

def query_selector_node_id(selector)
  command("DOM.querySelector", selector: selector, nodeId: @node_id).fetch("nodeId")
rescue KeyError
  raise Error
end

#screenshot(png_path) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 173

def screenshot(png_path)
  data = command("Page.captureScreenshot", timeout: TIMEOUT_SCREENSHOT).fetch("data")
  png_path.binwrite Base64.decode64(data)
rescue KeyError
  raise Error
end

#send(**message) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 135

def send(**message)
  message.merge! sessionId: @session_id if @session_id
  @input.write message.to_json, ?\0
end

#wait(event, timeout: nil) ⇒ Object 



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# File 'lib/nswtopo/chrome.rb', line 152

def wait(event, timeout: nil)
  Timeout.timeout(timeout) do
    messages.find do |message|
      message["method"] == event
    end
  end
rescue Timeout::Error
  raise Error
end