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author | Matthew Barnes <mbarnes@redhat.com> | 2010-06-14 06:37:27 +0800 |
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committer | Matthew Barnes <mbarnes@redhat.com> | 2010-06-14 09:31:58 +0800 |
commit | e6972011f01eab9f8d0a4584f32ee1e2a00f3231 (patch) | |
tree | 69e2a5e846965c3b369724b825f5b35c6d88056a /libart_lgpl/art_alphagamma.c | |
parent | 7f3377c78a560aa762e04d596b79f847c4acd870 (diff) | |
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Embed libart_lgpl and libgnomecanvas.
Both of these modules are deprecated and going away in GNOME 3 but we
still rely heavily on them for GnomeCalendar and ETable. So, welcome
to the island of unwanted libraries...
Diffstat (limited to 'libart_lgpl/art_alphagamma.c')
-rw-r--r-- | libart_lgpl/art_alphagamma.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/libart_lgpl/art_alphagamma.c b/libart_lgpl/art_alphagamma.c new file mode 100644 index 0000000000..4651883cf5 --- /dev/null +++ b/libart_lgpl/art_alphagamma.c @@ -0,0 +1,85 @@ +/* Libart_LGPL - library of basic graphic primitives + * Copyright (C) 1998 Raph Levien + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with this library; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +/* Some functions to build alphagamma tables */ + +#include "config.h" +#include "art_alphagamma.h" + +#include <math.h> + +/** + * art_alphagamma_new: Create a new #ArtAlphaGamma. + * @gamma: Gamma value. + * + * Create a new #ArtAlphaGamma for a specific value of @gamma. When + * correctly implemented (which is generally not the case in libart), + * alpha compositing with an alphagamma parameter is equivalent to + * applying the gamma transformation to source images, doing the alpha + * compositing (in linear intensity space), then applying the inverse + * gamma transformation, bringing it back to a gamma-adjusted + * intensity space. + * + * Return value: The newly created #ArtAlphaGamma. + **/ +ArtAlphaGamma * +art_alphagamma_new (double gamma) +{ + int tablesize; + ArtAlphaGamma *alphagamma; + int i; + int *table; + art_u8 *invtable; + double s, r_gamma; + + tablesize = ceil (gamma * 8); + if (tablesize < 10) + tablesize = 10; + + alphagamma = (ArtAlphaGamma *)art_alloc (sizeof(ArtAlphaGamma) + + ((1 << tablesize) - 1) * + sizeof(art_u8)); + alphagamma->gamma = gamma; + alphagamma->invtable_size = tablesize; + + table = alphagamma->table; + for (i = 0; i < 256; i++) + table[i] = (int)floor (((1 << tablesize) - 1) * + pow (i * (1.0 / 255), gamma) + 0.5); + + invtable = alphagamma->invtable; + s = 1.0 / ((1 << tablesize) - 1); + r_gamma = 1.0 / gamma; + for (i = 0; i < 1 << tablesize; i++) + invtable[i] = (int)floor (255 * pow (i * s, r_gamma) + 0.5); + + return alphagamma; +} + +/** + * art_alphagamma_free: Free an #ArtAlphaGamma. + * @alphagamma: An #ArtAlphaGamma. + * + * Frees the #ArtAlphaGamma. + **/ +void +art_alphagamma_free (ArtAlphaGamma *alphagamma) +{ + art_free (alphagamma); +} |