Another small sample, showing how to achieve some basic effects.

Originally committed to SVN as r1496.

OverLua/docs/test4.lua

@@ -0,0 +1,64 @@
+function render_frame(f, t)
+	-- Some data
+	local basex, basey = 100, 100
+	local thetext = overlua_datastring or "OverLua R0xx0rz?"
+
+	-- Create a new blank surface to draw on
+	local surf = cairo.image_surface_create(f.width, f.height, "argb32")
+	-- And a context to go with it. Drawing happens through the context.
+	local c = surf.create_context()
+	
+	-- The source video is 16:9 anamorphic, so create a scaling matrix
+	local scaling = cairo.matrix_create()
+	scaling.init_scale(f.width/853, f.height/480)
+	-- And set it for the surface
+	c.set_matrix(scaling)
+	
+	-- Create a surface of the video frame...
+	local fs = f.create_cairo_surface()
+	-- .. and blur it a bit
+	raster.gaussian_blur(fs, 2)
+	-- Then create a pattern from it, that can be used for filling shapes with
+	local fspattern = cairo.pattern_create_for_surface(fs)
+	-- Also apply the scaling matrix to the pattern
+	fspattern.set_matrix(scaling)
+	
+	-- Prepare a few things
+	c.select_font_face("Gill Sans Std UltraBold", "", "bold")
+	c.set_font_size(42)
+	c.set_line_width(4)
+	c.set_line_join("round")
+	
+	-- First stroke the text a bit above and to the left of main
+	c.move_to(basex-2, basey-2)
+	c.set_source_rgba(0.8, 0.8, 1, 0.8)
+	c.text_path(thetext)
+	c.stroke()
+	
+	-- Then a bit below and to the right, so it overlaps the first stroking a bit
+	c.move_to(basex+2, basey+2)
+	c.set_source_rgba(0.4, 0.4, 0.5, 0.8)
+	c.text_path(thetext)
+	c.stroke()
+	
+	-- And blur them both together, also softening the border
+	raster.gaussian_blur(surf, 3)
+	
+	-- Now prepare the main text fill and the real location
+	c.move_to(basex, basey)
+	c.text_path(thetext)
+	-- First a thing black outline
+	c.set_source_rgba(0, 0, 0, 1)
+	c.set_line_width(2)
+	c.stroke_preserve() -- _preserve version to keep the outline
+	-- Then use the blurred video frame as fill source
+	c.set_source(fspattern)
+	c.fill_preserve()
+	-- And create a very dark and rather transparent colour
+	-- Filling this on top of the first fill will create a darkening/reddening effect
+	c.set_source_rgba(0.2, 0, 0, 0.3)
+	c.fill()
+	
+	-- Finally draw the surface onto the video
+	f.overlay_cairo_surface(surf, 0, 0)
+end