Re: lua cairo

[Hakki Dogusan <dogusanh@...>]

Hi,

Wesley Smith wrote:
> Hi Hakki,
> I've been using you Cairo bindings for Lua.  Thanks very much for
> this.  It's working like a charm and your code is very clean.  One
> question I have is why you decided to represent the Cairo C structs as
> tables instead of using userdata.  An example:
>
> static void push_matrix(lua_State* L, cairo_matrix_t *matrix)
> {
>     lua_newtable(L);
>     set_numfield(L, "xx", matrix->xx);
>     set_numfield(L, "yx", matrix->yx);
>     set_numfield(L, "xy", matrix->xy);
>     set_numfield(L, "yy", matrix->yy);
>     set_numfield(L, "x0", matrix->x0);
>     set_numfield(L, "y0", matrix->y0);
> }
>
>
> When you get into for loops where you're using alot of the data
> structures represented this way, it adds quite an overhead.  I wonder
> if you would consider moving these kinds of things to a userdata
> representation for a future release?
>
> thanks,
> wes

Thank you for kind words.

I changed implementation of cairo_matrix_t, cairo_text_extents_t, 
cairo_fontt_extents_t to userdata. This change eliminated many "//WARN: 
different usage" comments :) You may search changes with "//.." in code.
Snippets.lua updated accordingly. There is a matrix test section at 
bottom of that file.

Usage is like:
    local m1 = cairo.Matrix()
    local m2 = cairo.Matrix{xx=0,yy=0.3}
    m1.x0 = m2.xx + 12.1
    cairo.matrix_init (m1, 1, 2, 3, 4, 5, 6)

    local e1 = cairo.TextExtents()
    local e2 = cairo.TextExtents{x_bearing=2.1}
    cairo.text_extents (cr, utf8, e1);
    x = 0.5-(e1.width/2 + e1.x_bearing);

    local f1 = cairo.FontExtents()
    cairo.font_extents (cr, f1);


You may get it here:
http://www.dogusan.net/dogusanh/download/luacairo-0.7.zip (~3.5Mb)


--
Regards,
Hakki Dogusan