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alogim

Member

Registered: 2015-08-25

Posts: 43

[SOLVED] [Conky + Cairo] Centering text

I am using Conky and Cairo to draw some nice things on my desktop. I would like to try to center some text. I was trying to follow this tutorial, however when porting that code into Lua code, the line

cairo_text_extents(cr, utf8, extents)

causes conky to stop without showing any error. I think the problem is that the data type cairo_text_extents_t is not recognized by lua. Is there any solution to this?

My ported code is as following:

local extents
local utf8 = "cairo"
local x, y
cairo_select_font_face(cr, "Ubuntu", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL)
cairo_set_font_size(cr, 13)
cairo_text_extents(cr, utf8, extents)
x = 128.0 - (extents.width / 2 + extents.x_bearing)
y = 128.0 - (extents.height / 2 + extents.y_bearing)

cairo_move_to (cr, x, y)
cairo_show_text (cr, utf8)

cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6)
cairo_set_line_width (cr, 6.0)
cairo_arc (cr, x, y, 10.0, 0, 2 * math.pi)
cairo_fill (cr)
cairo_move_to (cr, 128.0, 0)
cairo_rel_line_to (cr, 0, 256)
cairo_move_to (cr, 0, 128.0)
cairo_rel_line_to (cr, 256, 0)
cairo_stroke (cr)

Conky package is conky-cairo from the AUR and the version is the following:

conky -v
conky 1.10.6_pre compiled Tue  7 Feb 12:07:34 CET 2017 for Linux 4.9.7-1-ARCH x86_64

Compiled in features:

System config file: /etc/conky/conky.conf
Package library path: /usr/lib/conky


 General:
  * math
  * hddtemp
  * portmon
  * IPv6
  * Curl
  * RSS
  * iconv
  * Weather (METAR)
  * Weather (XOAP)
  * wireless
  * support for IBM/Lenovo notebooks
  * nvidia
  * builtin default configuration
  * old configuration syntax
  * Imlib2
  * apcupsd
  * iostats
  * ncurses
  * Internationalization support

 Lua bindings:
  * Cairo
  * Imlib2
  * RSVG
 X11:
  * Xdamage extension
  * Xinerama extension (virtual display)
  * Xshape extension (click through)
  * XDBE (double buffer extension)
  * Xft
  * ARGB visual
  * Own window

 Music detection:
  * MPD
  * MOC

 Default values:
  * Netdevice: eth0
  * Local configfile: $HOME/.conkyrc
  * Localedir: /usr/share/locale
  * Maximum netdevices: 64
  * Maximum text size: 16384
  * Size text buffer: 256

Last edited by alogim (2017-03-08 13:11:19)

alogim

Member

Registered: 2015-08-25

Posts: 43

Re: [SOLVED] [Conky + Cairo] Centering text

Solved by using the following:

local extents=cairo_text_extents_t:create()
tolua.takeownership(extents)
local utf8 = "cairo"
local x, y
cairo_select_font_face(cr, "Ubuntu", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL)
cairo_set_font_size(cr, 52)
cairo_text_extents(cr, utf8, extents)
x = 128.0 - (extents.width / 2 + extents.x_bearing)
y = 128.0 - (extents.height / 2 + extents.y_bearing)

cairo_move_to (cr, x, y)
cairo_show_text (cr, utf8)