Another, much more complex and interesting, sample.

Originally committed to SVN as r1545.

OverLua/docs/sample2.lua

@@ -0,0 +1,235 @@
+--[[
+
+Sample script for OverLua
+ - demonstrate basic reading in an ASS subtitle file and rendering its lines on the video
+ 
+Given into the public domain.
+(You can do anything you want with this file, with no restrictions whatsoever.
+ You don't get any warranties of any kind either, though.)
+ 
+Originally authored by Niels Martin Hansen.
+
+]]
+
+-- Set up some parameters
+timing_input_file = overlua_datastring
+-- Just the font name to use.
+font_name = "Arial"
+-- This is height in pixels, I suppose ;)
+font_size = 40
+-- This is the position of the _baseline_ of the text, neither top, bottom nor center!
+ypos = 50
+-- Duration of fadein/out in seconds
+fadetime = 1
+
+-- Error out if no file name was given (data= in Avisynth invocation)
+assert(timing_input_file, "Missing timing input file for sample effect.")
+
+
+-- ASS file reading stuff
+function parsenum(str)
+	return tonumber(str) or 0
+end
+function parse_ass_time(ass)
+	local h, m, s, cs = ass:match("(%d+):(%d+):(%d+)%.(%d+)")
+	return parsenum(cs)/100 + parsenum(s) + parsenum(m)*60 + parsenum(h)*3600
+end
+
+function parse_k_timing(text)
+	local syls = {}
+	local cleantext = ""
+	local i = 1
+	for timing, syltext in text:gmatch("{\\k(%d+)}([^{]*)") do
+		local syl = {dur = parsenum(timing)/100, text = syltext, i = i}
+		table.insert(syls, syl)
+		cleantext = cleantext .. syltext
+		i = i + 1
+	end
+	return syls, cleantext
+end
+
+function read_input_file(name)
+	for line in io.lines(name) do
+		local start_time, end_time, fx, text = line:match("Dialogue: 0,(.-),(.-),Default,,0000,0000,0000,(.-),(.*)")
+		if text then
+			local ls = {}
+			ls.start_time = parse_ass_time(start_time)
+			ls.end_time = parse_ass_time(end_time)
+			ls.fx = fx
+			ls.rawtext = text
+			ls.kara, ls.cleantext = parse_k_timing(text)
+			table.insert(lines, ls)
+		end
+	end
+end
+
+function init()
+	if inited then return end
+	inited = true
+	
+	lines = {}
+	read_input_file(timing_input_file)
+end
+
+
+-- Get/create a "sparks" texture, singleton-style
+function get_sparks_texture(width, height)
+	-- Check if it already exists, just return it then
+	if sparks_texture then return sparks_texture end
+	-- We'll make a 128x128 black image with some blurred whitish spots on
+	local surf = cairo.image_surface_create(128, 128, "rgb24")
+	local c = surf.create_context()
+	-- Paint it all black
+	c.set_source_rgb(0,0,0)
+	c.paint()
+	-- Then create a very light yellow
+	c.set_source_rgb(1,1,0.9)
+	-- And create 50 small, random circles
+	for i = 1, 50 do
+		local x, y = math.random(120)+4, math.random(120)+4
+		c.arc(x, y, 3, 0, 2*math.pi)
+		c.fill()
+	end
+	-- And blur the result
+	raster.gaussian_blur(surf, 2.5)
+	
+	-- Then create a texture of it.
+	-- sparks_texture becomes a global variable
+	sparks_texture = cairo.pattern_create_for_surface(surf)
+	sparks_texture.set_extend("repeat")
+	
+	return sparks_texture
+end
+
+
+function render_frame(f, t)
+	init()
+	
+	-- Create a blurred copy of the video frame
+	local fsurf = f.create_cairo_surface()
+	raster.gaussian_blur(fsurf, 5)
+	
+	-- Function to create "wobble" effect on the text
+	local function blubble_mapper(x, y)
+		local nx = x + math.sin(x/30 + y/10 + t*2.0)*3
+		local ny = y + math.cos(y/20 + x/20 + t*2.3)*3
+		return nx, ny
+	end
+	
+	-- Find lines to be drawn
+	for i, line in pairs(lines) do
+		-- Check if the line is within time range.
+		-- "In time range" means starts fadetime seconds later than current time or ends "fadetime" seconds earlier.
+		if line.start_time <= t+fadetime and line.end_time > t-fadetime then
+			local x = 0
+			local y = ypos
+			
+			-- Prepare a surface to draw on
+			local surf = cairo.image_surface_create(f.width, 200, "argb32")
+			local c = surf.create_context()
+			-- Select the font
+			c.select_font_face(font_name)
+			c.set_font_size(font_size)
+			-- Get the text extents for the line text if we don't have them already
+			if not line.te then line.te = c.text_extents(line.cleantext); line.fe = c.font_extents() end
+			-- And calculate the start X to have the line centered
+			x = (f.width - line.te.width) / 2 - line.te.x_bearing
+			-- Then make a path for the text
+			c.move_to(x, y)
+			c.text_path(line.cleantext)
+			
+			-- Create the "wobble" effect on the text
+			-- First get a Path object for the text
+			local path = c.copy_path()
+			-- Run the path through the mapping function
+			path.map_coords(blubble_mapper)
+			-- Clear the path in the context
+			c.new_path()
+			-- And add the modified path back
+			c.append_path(path)
+			
+			-- Prepare drawing the text outline
+			c.set_line_width(8)
+			-- Red outline
+			c.set_source_rgba(1, 0, 0, 1)
+			-- Stroke it but keep the path in the canvas
+			c.stroke_preserve()
+			-- Blur this outline
+			raster.gaussian_blur(surf, 1.5)
+			-- Prepare another, smaller outline on top
+			c.set_line_width(3)
+			-- This one is white
+			c.set_source_rgba(1, 1, 1, 1)
+			-- Stroke that one too, but clear the path afterwards
+			c.stroke()
+			
+			-- Now loop over the syllables to draw them one by one
+			local sumdur = line.start_time
+			for j, syl in pairs(line.kara) do
+				-- Get the text extents for this syllable
+				if not syl.te then syl.te = c.text_extents(syl.text) end
+				-- Prepare the path
+				c.move_to(x, y)
+				c.text_path(syl.text)
+				-- Wobble the path; this will work because the mapper is deterministic on X, Y and timestamp
+				local path = c.copy_path()
+				path.map_coords(blubble_mapper)
+				c.new_path()
+				c.append_path(path)
+				-- And advance X position
+				x = x + syl.te.x_advance
+				-- Now figure out whether this syllable is the active one or not
+				-- Use a more complicated test, this makes the first syllable be highlighted
+				-- also while the line is fading in, and the last while the line is fading out.
+				if (syl.i == 1 and t < sumdur+syl.dur) or
+						(syl.i == #line.kara and t > sumdur) or
+						(t >= sumdur and t < sumdur+syl.dur) then
+					-- Get the "sparks" texture
+					local sparks = get_sparks_texture()
+					-- Prepare a transformation matrix for it
+					local texmat = cairo.matrix_create()
+					texmat.init_rotate(t/10)
+					texmat.scale(3, 3)
+					sparks.set_matrix(texmat)
+					-- Use the texture
+					c.set_source(sparks)
+					-- And fill the path
+					c.fill()
+				else
+					-- Not the active syllable, fill it with a blurred video frame
+					-- Remember fsurf is the blurred video frame
+					c.set_source_surface(fsurf, 0, 0)
+					c.fill_preserve()
+					-- Also add a slight darkening to the fill
+					c.set_source_rgba(0, 0, 0, 0.2)
+					c.fill()
+				end
+				-- Advance the sum of syllable durations
+				sumdur = sumdur + syl.dur
+			end
+			
+			-- Figure out whether we're past the actual start/end time of the line and do some fading then
+			local final = surf
+			if t < line.start_time or t > line.end_time then
+				-- Make invisibility the amount the line is invisible
+				local invisibility
+				if t < line.start_time then
+					invisibility = (line.start_time - t) / fadetime
+				else
+					invisibility = (t - line.end_time) / fadetime
+				end
+				-- We'll need a new surface object here
+				final = cairo.image_surface_create(surf.get_width(), surf.get_height(), "argb32")
+				local c = final.create_context()
+				-- So we can alpha-blend the original drawn text image onto it using invisibility as alpha
+				c.set_source_surface(surf, 0, 0)
+				c.paint_with_alpha(1-invisibility)
+				-- And then do some heavy blur-out
+				raster.gaussian_blur(final, invisibility*15)
+			end
+			
+			-- Finally just overlay the text image on the video
+			f.overlay_cairo_surface(final, 0, 0)
+		end
+	end
+end