Re: Drawing a halo around text

[Behdad Esfahbod <behdad behdad org>]

On Fri, 2007-10-26 at 10:11 -0500, Matt Hoosier wrote:
> Hi,
> 
> I'd like to draw some text over the top of a user-supplied splash
> screen. Because I can't know what the color scheme contained in that
> image will be, I need to do something like paint a small (1-pixel ?)
> border of known color around the edges of my glyphs, in order to
> guarantee that the lettering is visible.
> 
> Is there a way to convince Pango to do that sort of thing?

Yes and no. You need to do it yourself, but pango gives you the tools
for.

First, use pangocairo with gdk.  Then you can do things like:

  cairo_move_to (cr, x, y);
  cairo_pango_layout_path (cr, layout);

  /* blue halo */
  cairo_set_source_rgba (cr, 0., 0., 1., .5);
  cairo_set_line_width (cr, 2.);
  cairo_stroke_preserve (cr);

  /* green letters */
  cairo_set_source_rgb (cr, 0., 1., 0.);
  cairo_fill (cr);

An uglier but possibly faster option is to render the text 5 times:

  /* blue halo */
  cairo_set_source_rgb (cr, 0., 0., 1.);
  cairo_move_to (cr, x-1, y); cairo_pango_show_layout (cr, layout);
  cairo_move_to (cr, x+1, y); cairo_pango_show_layout (cr, layout);
  cairo_move_to (cr, x, y-1); cairo_pango_show_layout (cr, layout);
  cairo_move_to (cr, x, y+1); cairo_pango_show_layout (cr, layout);

  /* green letters */
  cairo_set_source_rgb (cr, 0., 1., 0.);
  cairo_move_to (cr, x, y); cairo_pango_show_layout (cr, layout);

> --Matt

Cheers,
-- 
behdad
http://behdad.org/

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