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 /**
  22  * SECTION:adg-matrix
  23  * @Section_Id:AdgMatrix
  24  * @title: AdgMatrix
  25  * @short_description: A wrapper for #cairo_matrix_t
  26  *
  27  * AdgMatrix is a wrapper in #GType syntax of the #cairo_matrix_t struct.
  28  **/
  29
  30 /**
  31  * AdgMatrix:
  32  *
  33  * Another name for #cairo_matrix_t: check its documentation for the
  34  * fields description and visibility details.
  35  **/
  36
  37
  38 #include "adg-matrix.h"
  39
  40 #include <string.h>
  41 #include <math.h>
  42
  43
  44 static AdgMatrix null_matrix = { 0., 0., 0., 0., 0., 0. };
  45 static AdgMatrix identity_matrix = { 1., 0., 0., 1., 0., 0. };
  46
  47
  48 GType
  49 adg_matrix_get_type(void)
  50 {
  51     static int matrix_type = 0;
  52
  53     if (G_UNLIKELY(matrix_type == 0))
  54         matrix_type = g_boxed_type_register_static("AdgMatrix",
  55                                                    (GBoxedCopyFunc) adg_matrix_dup,
  56                                                    g_free);
  57
  58     return matrix_type;
  59 }
  60
  61 /**
  62  * adg_matrix_dup:
  63  * @matrix: an #AdgMatrix structure
  64  *
  65  * Duplicates @matrix.
  66  *
  67  * Returns: the duplicate of @matrix: must be freed with g_free()
  68  *          when no longer needed.
  69  **/
  70 AdgMatrix *
  71 adg_matrix_dup(const AdgMatrix *matrix)
  72 {
  73     g_return_val_if_fail(matrix != NULL, NULL);
  74
  75     return g_memdup(matrix, sizeof(AdgMatrix));
  76 }
  77
  78 /**
  79  * adg_matrix_get_fallback:
  80  *
  81  * Gets a fallback matrix. The fallback matrix is a statically allocated
  82  * identity matrix.
  83  *
  84  * Returns: the fallback matrix
  85  **/
  86 const AdgMatrix *
  87 adg_matrix_get_fallback(void)
  88 {
  89     return &identity_matrix;
  90 }
  91
  92 /**
  93  * adg_matrix_init_null:
  94  * @matrix: the #AdgMatrix to nullify
  95  *
  96  * Nullifies a matrix, setting all its components to 0.
  97  **/
  98 void
  99 adg_matrix_init_null(AdgMatrix *matrix)
 100 {
 101     memcpy(matrix, &null_matrix, sizeof(AdgMatrix));
 102 }
 103
 104 /**
 105  * adg_matrix_is_null:
 106  * @matrix: the #AdgMatrix to check
 107  *
 108  * Checks if a matrix is a nullified matrix.
 109  *
 110  * Returns: %TRUE if the matrix is a null matrix, %FALSE otherwise
 111  **/
 112 gboolean
 113 adg_matrix_is_null(const AdgMatrix *matrix)
 114 {
 115     return memcmp(matrix, &null_matrix, sizeof(AdgMatrix)) == 0;
 116 }
 117
 118 /**
 119  * adg_matrix_copy:
 120  * @matrix: the destination #AdgMatrix
 121  * @src: the source #AdgMatrix
 122  *
 123  * Copies @matrix to @dst.
 124  *
 125  * Returns: @matrix
 126  **/
 127 AdgMatrix *
 128 adg_matrix_copy(AdgMatrix *matrix, const AdgMatrix *src)
 129 {
 130     g_return_val_if_fail(matrix != NULL, matrix);
 131     g_return_val_if_fail(src != NULL, matrix);
 132
 133     memcpy(matrix, src, sizeof(AdgMatrix));
 134
 135     return matrix;
 136 }
 137
 138 /**
 139  * adg_matrix_equal:
 140  * @matrix1: an #AdgMatrix
 141  * @matrix2: an #AdgMatrix
 142  *
 143  * Compares @matrix1 and @matrix2 and returns %TRUE if the matrices are equal.
 144  *
 145  * Returns: %TRUE if @matrix1 is equal to @matrix2, %FALSE otherwise
 146  **/
 147 gboolean
 148 adg_matrix_equal(const AdgMatrix *matrix1, const AdgMatrix *matrix2)
 149 {
 150     g_return_val_if_fail(matrix1 != NULL, FALSE);
 151     g_return_val_if_fail(matrix2 != NULL, FALSE);
 152
 153     return memcmp(matrix1, matrix2, sizeof(AdgMatrix)) == 0;
 154 }
 155
 156 /**
 157  * adg_matrix_init_reflection:
 158  * @matrix: the destination #AdgMatrix
 159  * @radians: angle of the mirroring axis, in radians
 160  *
 161  * Initialized @matrix to a transformation that reflects arond an axis
 162  * rotated by @radians and passing throught the origin (0, 0).
 163  **/
 164 void
 165 adg_matrix_init_reflection(AdgMatrix *matrix, double radians)
 166 {
 167     double s2 = sin(2*radians);
 168     double c2 = cos(2*radians);
 169
 170     cairo_matrix_init(matrix, c2, s2, s2, -c2, 0, 0);
 171 }