adg/adg-matrix.c

   1 /* ADG - Automatic Drawing Generation
   2  * Copyright (C) 2007,2008,2009 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  * SECTION:matrix
  22  * @title: AdgMatrix
  23  * @short_description: A wrapper for the cairo_matrix_t struct
  24  *
  25  * The AdgMatrix is essentially a wrapper for #cairo_matrix_t structures.
  26  */
  27
  28 #include "adg-matrix.h"
  29
  30 #include <string.h>
  31 #include <math.h>
  32
  33
  34 static AdgMatrix null_matrix = { 0., 0., 0., 0., 0., 0. };
  35 static AdgMatrix identity_matrix = { 1., 0., 0., 1., 0., 0. };
  36
  37
  38 GType
  39 adg_matrix_get_type(void)
  40 {
  41     static int matrix_type = 0;
  42
  43     if (G_UNLIKELY(matrix_type == 0))
  44         matrix_type = g_boxed_type_register_static("AdgMatrix",
  45                                                    (GBoxedCopyFunc) adg_matrix_dup,
  46                                                    g_free);
  47
  48     return matrix_type;
  49 }
  50
  51 /**
  52  * adg_matrix_dup:
  53  * @matrix: an #AdgMatrix structure
  54  *
  55  * Duplicates @matrix.
  56  *
  57  * Return value: the duplicate of @matrix: must be freed with g_free()
  58  *               when no longer needed.
  59  */
  60 AdgMatrix *
  61 adg_matrix_dup(const AdgMatrix *matrix)
  62 {
  63     g_return_val_if_fail(matrix != NULL, NULL);
  64
  65     return g_memdup(matrix, sizeof(AdgMatrix));
  66 }
  67
  68 /**
  69  * adg_matrix_get_fallback:
  70  *
  71  * Gets a fallback matrix. The fallback matrix is a statically allocated
  72  * identity matrix.
  73  *
  74  * Return value: the fallback matrix
  75  */
  76 const AdgMatrix *
  77 adg_matrix_get_fallback(void)
  78 {
  79     return &identity_matrix;
  80 }
  81
  82 /**
  83  * adg_matrix_init_null:
  84  * @matrix: the #AdgMatrix to nullify
  85  *
  86  * Nullifies a matrix, setting all its components to 0.
  87  */
  88 void
  89 adg_matrix_init_null(AdgMatrix *matrix)
  90 {
  91     memcpy(matrix, &null_matrix, sizeof(AdgMatrix));
  92 }
  93
  94 /**
  95  * adg_matrix_is_null:
  96  * @matrix: the #AdgMatrix to check
  97  *
  98  * Checks if a matrix is a nullified matrix.
  99  *
 100  * Return value: %TRUE if the matrix is a null matrix, %FALSE otherwise
 101  */
 102 gboolean
 103 adg_matrix_is_null(const AdgMatrix *matrix)
 104 {
 105     return memcmp(matrix, &null_matrix, sizeof(AdgMatrix)) == 0;
 106 }
 107
 108 /**
 109  * adg_matrix_copy:
 110  * @matrix: the destination #AdgMatrix
 111  * @src: the source #AdgMatrix
 112  *
 113  * Copies @matrix to @dst.
 114  *
 115  * Return value: @matrix
 116  **/
 117 AdgMatrix *
 118 adg_matrix_copy(AdgMatrix *matrix, const AdgMatrix *src)
 119 {
 120     g_return_val_if_fail(matrix != NULL, matrix);
 121     g_return_val_if_fail(src != NULL, matrix);
 122
 123     memcpy(matrix, src, sizeof(AdgMatrix));
 124
 125     return matrix;
 126 }
 127
 128 /**
 129  * adg_matrix_equal:
 130  * @matrix1: an #AdgMatrix
 131  * @matrix2: an #AdgMatrix
 132  *
 133  * Compares @matrix1 and @matrix2 and returns %TRUE if the matrices are equal.
 134  *
 135  * Return value: %TRUE if @matrix1 is equal to @matrix2, %FALSE otherwise
 136  */
 137 gboolean
 138 adg_matrix_equal(const AdgMatrix *matrix1, const AdgMatrix *matrix2)
 139 {
 140     g_return_val_if_fail(matrix1 != NULL, FALSE);
 141     g_return_val_if_fail(matrix2 != NULL, FALSE);
 142
 143     return memcmp(matrix1, matrix2, sizeof(AdgMatrix)) == 0;
 144 }
 145
 146 /**
 147  * adg_matrix_init_reflection:
 148  * @matrix: the destination #AdgMatrix
 149  * @radians: angle of the mirroring axis, in radians
 150  *
 151  * Initialized @matrix to a transformation that reflects arond an axis
 152  * rotated by @radians and passing throught the origin (0, 0).
 153  **/
 154 void
 155 adg_matrix_init_reflection(AdgMatrix *matrix, double radians)
 156 {
 157     double s2 = sin(2*radians);
 158     double c2 = cos(2*radians);
 159
 160     cairo_matrix_init(matrix, c2, s2, s2, -c2, 0, 0);
 161 }