cpml/cpml-util.c

   1 /* CPML - Cairo Path Manipulation Library
   2  * Copyright (C) 2008, 2009  Nicola Fontana <ntd at entidi.it>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301, USA.
  18  */
  19
  20
  21 /**
  22  * SECTION:cpml-util
  23  * @Section_Id:utilities
  24  * @title: Utilities
  25  * @short_description: Assorted macros and functions
  26  *
  27  * Collection of macros and functions that do not fit inside any other topic.
  28  **/
  29
  30
  31 #include "cpml-util.h"
  32 #include <math.h>
  33
  34
  35 /**
  36  * CPML_GNUC_CONST:
  37  *
  38  * To be appended at the end of a function to notice the compiler (gcc)
  39  * that the return value is constant.
  40  *
  41  * The coded is an adaptation of the #G_GNUC_CONST macro defined by
  42  * glib-2.18.3 in <filename>glib/gmacros.h</filename>.
  43  **/
  44
  45 /**
  46  * CAIRO_HAS_ARC_SUPPORT:
  47  *
  48  * Defined to 1 if cairo has arc support. Actually (cairo-1.8.8) cairo
  49  * does not have arc support so it is expected this define will be always
  50  * undefined.
  51  **/
  52
  53 /**
  54  * CAIRO_PATH_ARC_TO:
  55  *
  56  * The code of an arc-to primitive. This is expected to be defined by
  57  * cairo whenever (and if) cairo will support arc primitives. Actually
  58  * it resolves to an harcoded %100 constant.
  59  *
  60  * Check out the #CpmlArc section for further information.
  61  **/
  62
  63
  64 /**
  65  * cpml_angle:
  66  * @angle: an angle in radians
  67  *
  68  * Normalizes @angle, that is returns the equivalent radians value
  69  * between the range %M_PI (inclusive) and %-M_PI (exclusive).
  70  *
  71  * Returns: an equivalent value in radians
  72  **/
  73 double
  74 cpml_angle(double angle)
  75 {
  76     while (angle > M_PI)
  77         angle -= M_PI * 2;
  78
  79     while (angle <= -M_PI)
  80         angle += M_PI * 2;
  81
  82     return angle;
  83 }