Full screenshots don't show page content

[Odaeus]

Hi, I'm finding Ferrum to be a great lib, thank you! I have a bug to report when taking screenshots.

The full: true option when passed to #screenshot does not show the full page, instead it only renders the visible area of the page according to the viewport and then the rest is a solid background colour. I think the tests don't catch this because they only check the image dimensions.

Here's an example:

b = Ferrum::Browser.new
b.goto "http://www.csszengarden.com/"
b.resize width: 800, height: 200
b.screenshot(path: "zg200.png", full: true)

b.resize width: 800, height: 600
b.screenshot(path: "zg600.png", full: true)

b.resize width: 800, height: b.evaluate("document.documentElement.offsetHeight")
b.screenshot(path: "zgfull.png", full: true)

[route]

Thanks for reporting, it's great that it's a public website I'll take a look.

[Mifrill]

it "issue #18" do
	browser.goto "http://www.csszengarden.com/"
	sleep 1
	browser.resize width: 800, height: 200
	browser.screenshot(path: file, full: true)
	expect(File.exist?(file)).to be true
	expect(browser.viewport_size).to eq([800, 200])
end

Result in https://github.com/Mifrill/ferrum/tree/issue%2318_full-screenshots-dont-show-page-content