Class: LoaderDetector::Detector

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

Defined Under Namespace

Classes: IDnotSetError, ThresholdNegativeError

Constant Summary collapse

@@logger = 
Logger.new(STDOUT)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(driver, threshold = 0, frame_count = 10, timeout = 10) ⇒ Detector

Sets the id of the window of which the program will take screenshots and creates the two initial screenshots.

Parameters:

  • id (String) —

    id of the window to be screenshotted

  • threshold (Integer) (defaults to: 0) —

    threshold for the pixel difference between two screenshots. If the difference is below the threshold the website is assumed to be loaded.

  • frame_count (Integer) (defaults to: 10) —

    number of times the pixel difference has to be below the threshold to assume that the website is loaded.

  • timeout (Integer) (defaults to: 10) —

    number of seconds the program will wait for the website to load.

Raises:



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# File 'lib/loader_detector.rb', line 31

def initialize( driver, threshold = 0, frame_count = 10, timeout = 10 )
    raise IDnotSetError.new if id == ""
    raise ThresholdNegativeError.new if threshold < 0

    @driver = driver
    @threshold = threshold
    @frame_count = frame_count
    @timeout = timeout
end

Instance Attribute Details

#id ⇒ Object (readonly)

Returns the value of attribute id.



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# File 'lib/loader_detector.rb', line 20

def id
  @id
end

#threshold ⇒ Object (readonly)

Returns the value of attribute threshold.



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# File 'lib/loader_detector.rb', line 20

def threshold
  @threshold
end

Instance Method Details

#wait_until_content_loaded ⇒ Object

Checks if a website has finished loading already. Calls the comparison algorithm, if the pixel difference is below the threshold 10 times in a row it assumes that the website doesn’t change anymore.



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# File 'lib/loader_detector.rb', line 42

def wait_until_content_loaded
    imagefile1 = Tempfile.new(['image1', '.pnm'])
    imagefile2 = Tempfile.new(['image2', '.pnm'])

    @driver.pam_screenshot_file(imagefile1.path)

    count = 0
    t0 = Time.now

    while Time.now - t0 < @timeout do

        @driver.pam_screenshot_file(imagefile2.path)

        count = difference_detected?(imagefile1, imagefile2) ? 0 : count + 1

        begin
            File.rename(imagefile2.path, imagefile1.path)
        rescue Errno::ENOENT
            logger.warn("Can't rename imagefile2")
        end

        if count >= @frame_count
            yield if block_given?
            return true
        end
    end

    logger.warn("check_loading timed out. Couldn't detect a loaded website.")

    return false
end