`module Printing`

Helpers for printing the current page to PDF.

Definitions

`def print(orientation: nil, scale: nil, background: nil, page: nil, margin: nil, page_ranges: nil, shrink_to_fit: nil)`

Print the current page as a PDF and return the raw binary data.

All margin and page measurements are in centimetres. The W3C WebDriver default page size is US Letter (21.59 × 27.94 cm) with 1 cm margins.

Signature

parameter　orientation　String | Nil: "portrait" or "landscape". Default: "portrait".
parameter　scale　Float | Nil: Scaling factor between 0.1 and 2.0. Default: 1.0.
parameter　background　Boolean | Nil: Whether to print background graphics and colours. Default: false.
parameter　page　Hash | Nil: Page dimensions in cm. Keys: :width, :height.
parameter　margin　Hash | Nil: Page margins in cm. Keys: :top, :bottom, :left, :right.
parameter　page_ranges　Array(String) | Nil: Page ranges to print, e.g. ["1-5", "8"]. Default: all pages.
parameter　shrink_to_fit　Boolean | Nil: Whether to shrink content to fit the page. Default: true.
returns　String: The raw PDF binary data.

Implementation

def print(orientation: nil, scale: nil, background: nil, page: nil, margin: nil, page_ranges: nil, shrink_to_fit: nil)
	parameters = {
		orientation: orientation,
		scale: scale,
		background: background,
		page: page,
		margin: margin,
		pageRanges: page_ranges,
		shrinkToFit: shrink_to_fit,
	}.compact
	
	# Synchronise with Chrome's rendering pipeline before issuing the print
	# command. The underlying CDP call (Page.printToPDF) is synchronous: if
	# the renderer process has not yet fully initialised its print pipeline
	# by the time the command arrives, Chrome returns JSON-RPC error -32000
	# ("Printing failed") with no retry. A JavaScript round-trip forces
	# ChromeDriver to wait for the renderer to be live (a JS execution
	# context must exist), which also guarantees the print pipeline is ready.
	# Without this, fast-loading pages can trigger the race intermittently.
	session.execute("return document.readyState")
	
	reply = session.post("print", parameters)
	
	return Base64.decode64(reply)
end