Awesomium Pool Interface

cl_browserpool.lua

if browserpool then return end -- ignore Lua refresh

local table = table
local vgui = vgui

_G.browserpool = {}

--
-- Debug variable which will allow outputting messages if enabled.
-- @type boolean
--
local DEBUG = true

--
-- Array of available, pooled browsers
-- @type table
--
local available = {}

--
-- Array of active, pooled browsers.
-- @type table
--
local active = {}

--
-- Minimum number of active browsers to be pooled.
-- @type Number
--
local numMin = 2

--
-- Number of currently active browsers.
-- @type Number
--
local numActive = 0

--
-- Default URL to set browsers on setup/teardown.
-- @type String
--
local defaultUrl = "about:blank"

--
-- JavaScript code to remove an object's property.
-- @type String
--
local JS_RemoveProp = "delete %s.%s;"

--
-- Helper function to setup/teardown a browser panel.
--
-- @param panel?	Browser panel to be cleaned up.
-- @return Panel	DMediaPlayerHTML panel instance.
--	
local function setupPanel( panel )

	-- Create a new panel if it wasn't passed in
	if panel then
		panel:Stop()
	else
		panel = vgui.Create("DMediaPlayerHTML")
	end

	-- Hide panel
	-- panel:SetSize(0, 0)
	panel:SetPos(0, 0)

	-- Disable input
	panel:SetKeyBoardInputEnabled(false)
	panel:SetMouseInputEnabled(false)

	-- Browser panels are usually manually drawn, use a regular panel if not
	panel:SetPaintedManually(true)

	-- Set default URL
	panel:OpenURL( defaultUrl )

	-- Remove any added function callbacks
	for obj, tbl in pairs(panel.Callbacks) do
		if obj ~= "console" then
			for funcname, _ in pairs(tbl) do
				panel:QueueJavascript(JS_RemoveProp:format(obj, funcname))
			end
		end
	end

	return panel

end

--
-- Retrieves an available browser panel from the pool. Otherwise, a new panel
-- will be created.
--
-- @return Panel	DMediaPlayerHTML panel instance.
--
function browserpool.get()

	local panel

	-- Check if there's an available panel
	if #available > 0 then
		panel = table.remove( available )
	else

		-- TODO: impose limit on number of active browsers

		-- Otherwise, create a new panel
		panel = setupPanel()
		numActive = numActive + 1

		if DEBUG then
			print( "browserpool: Spawned new browser [Active: "..numActive.."]" )
		end

	end

	table.insert( active, panel )

	return panel

end

--
-- Releases the given browser panel from the active pool.
--
-- @param panel		Browser panel to be released.
-- @return boolean	Whether the panel was successfully removed.
--
function browserpool.release( panel )

	if not panel then return end

	local key = table.RemoveByValue( active, panel )

	-- Unable to find active browser panel
	if not key then
		ErrorNoHalt( "browserpool: Attempted to release unactive browser.\n" )
		debug.Trace()
		return false
	end

	-- Remove panel if there are more active than the minimum pool size
	if numActive > numMin then

		panel:Remove()
		numActive = numActive - 1

		if DEBUG then
			print( "browserpool: Destroyed browser [Active: "..numActive.."]" )
		end

	else

		-- Cleanup panel
		setupPanel( panel )

		-- Add to the pool
		table.insert( available, panel )

	end

	return true

end