pngsurface.lua

local argcheck = require 'argcheck'
local class = require 'class'
local ffi = require 'ffi'
local cairo = require 'cairo.env'
local C = cairo.C

local PNGImageSurface = class.new('cairo.PNGImageSurface', 'cairo.ImageSurface')
local Surface = class.metatable('cairo.Surface')
cairo.PNGImageSurface = PNGImageSurface

PNGImageSurface.__init = argcheck{
   {name="self", type="cairo.PNGImageSurface"},
   {name="filename", type="string"},
   call =
      function(self, filename)
         self.C = C.cairo_image_surface_create_from_png(filename)
         ffi.gc(self.C, C.cairo_surface_destroy)
         return self
      end
}

Surface.writeToPNG = argcheck{
   {name="self", type="cairo.Surface"},
   {name="filename", type="string"},
   call =
      function(self, filename)
         return C.cairo_surface_write_to_png(self.C, filename)
      end
}

Surface.writeToPNGStream = argcheck{
   {name="self", type="cairo.Surface"},
   {name="write_func", type="function"},
   {name="closure", type="void*"},
   call =
      function(self, write_func, closure)
         return C.cairo_surface_write_to_png_stream(self.C, write_func, closure)
      end
}