Class: Thumbshooter

Inherits:
Object
  • Object
show all
Defined in:
lib/thumbshooter.rb,
lib/webkit2png.rb

Overview

Binding for webkit2png

Constant Summary collapse

IMAGE_TYPE = 
'png'
CHECK_LOADING_STATUS_INTERVAL = 
0.1
WEBKIT2PNG = 
File.dirname(__FILE__) + '/webkit2png.rb'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Thumbshooter

screen: dimension of the view part (w * h) i.e. 800x800 resize: resize thumbshot (w * h) i.e. 160x160 format: png (any others?) timeout: timeout for the page to load



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# File 'lib/thumbshooter.rb', line 23

def initialize
  @timeout     = 30
  @state       = 'waiting'
  @progress    = 0
  @started_at  = nil
  @output      = nil
  self.screen_size = '1024x768'
end

Instance Attribute Details

#timeout ⇒ Object

Returns the value of attribute timeout.



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# File 'lib/webkit2png.rb', line 26

def timeout
  @timeout
end

Class Method Details

.use_xvfb ⇒ Object

use X window virtual framebuffer?



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# File 'lib/thumbshooter.rb', line 12

def self.use_xvfb
  @use_xvfb
end

.use_xvfb=(value) ⇒ Object

use X window virtual framebuffer?



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# File 'lib/thumbshooter.rb', line 7

def self.use_xvfb=(value)
  @use_xvfb = value
end

Instance Method Details

#create(url, output = nil) ⇒ Object

creates a thumbshot returns it if no output-path given



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# File 'lib/thumbshooter.rb', line 46

def create(url, output=nil)
  args = @args
  args << "--output=#{output}" if output
  
  # execute webkit2png-script and save stdout
  command = ''
  if self.class.use_xvfb
    # calculate screen size
    screen = @screen ? @screen.split('x').collect{|i|i.to_i+100}.join("x") : '1024x768'
    # add xvfb wrapper
    command << "xvfb-run -n 14 --server-args='-screen 0, #{screen}x24' "
  end
  
  command << "#{WEBKIT2PNG} '#{url}' #{args}"
  
  img    = `#{command} 2>&1`
  status = $?.to_i
  pos    = img.index("\211PNG")
  
  if status != 0 || !pos
    raise "#{WEBKIT2PNG} failed with status #{status}: #{img}"
  end
  
  # strip beginning rubish
  img = img[pos..-1]
  
  if @resize
    width,height = @resize.split("x")
    img = resize(img,width,height)
  end
  
  img
end

#create_by_html(html) ⇒ Object

creates a thumb from direct html using a temporary file



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# File 'lib/thumbshooter.rb', line 81

def create_by_html(html)
  tmp_file = Tempfile.new('thumbshot')
  tmp_file.write(html)
  tmp_file.close
  
  begin
    create(tmp_file.path)
  ensure
    #tmp_file.close!
  end
end

#generate(url) ⇒ Object 



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# File 'lib/webkit2png.rb', line 42

def generate(url)
  app     = Qt::Application.new(ARGV)
  webview = Qt::WebView.new()
  
  webview.connect(SIGNAL("loadStarted()")) do
    @started_at = Time.now.to_i
  end
  
  webview.connect(SIGNAL('loadFinished(bool)')) do |result|
    if result
      @state = 'finished-success'
    else
      @state = 'finished-fail'
      @progress = false
    end
    suspend_thread # Give it enough time to switch to the sentinel thread and avoid an empty exec loop
  end
  
  webview.connect(SIGNAL("loadProgress(int)")) do |progress|
    @progress = progress
    suspend_thread if has_reached_time_out?
  end
  
  # Hide the scrollbars
  mainFrame = webview.page.mainFrame
  mainFrame.setScrollBarPolicy(Qt::Horizontal, Qt::ScrollBarAlwaysOff)
  mainFrame.setScrollBarPolicy(Qt::Vertical,   Qt::ScrollBarAlwaysOff)
  
  webview.load(Qt::Url.new(url))
  webview.resize(@screen_size)
  webview.show
  render_page_thread = Thread.new do
    app.exec
  end
  
  check_status_thread = Thread.new do
    while true do
      sleep CHECK_LOADING_STATUS_INTERVAL
      if @state =~ /^finished/ || has_reached_time_out?
        # Save a screenshot if page finished loaded or it has timed out with 50%+ completion
        if @state == 'finished-success' || (@progress && @progress >= 50)
          save_screenshot(webview)
        end
        render_page_thread.kill
        break
      end
    end
  end
  
  check_status_thread.join
  render_page_thread.join
  
  # percentage of completion
  @progress
end

#output ⇒ Object 



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# File 'lib/webkit2png.rb', line 98

def output
  @output
end

#progress ⇒ Object 



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# File 'lib/webkit2png.rb', line 102

def progress
  @progress
end

#screen_size=(value) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/webkit2png.rb', line 37

def screen_size=(value)
  raise ArgumentError, "invalid size: #{value}" unless value =~ /^(\d+)x(\d+$)/
  @screen_size = Qt::Size.new($~[1].to_i, $~[2].to_i)
end