src/cpml/cpml-extents.c

   1 /* CPML - Cairo Path Manipulation Library
   2  * Copyright (C) 2007-2021  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-extents
  23  * @Section_Id:Extents
  24  * @title: CpmlExtents
  25  * @short_description: A rectangular area representing a bounding box
  26  *
  27  * The #CpmlExtents struct groups two pairs representing the rectangular
  28  * area of a bounding box.
  29  *
  30  * Since: 1.0
  31  **/
  32
  33 /**
  34  * CpmlExtents:
  35  * @is_defined: set to 0 when these extents are undefined
  36  * @org: the lowest x,y coordinates
  37  * @size: the width (x) and height (y) of the extents
  38  *
  39  * A structure defining a bounding box area. These APIs expect the
  40  * size of the extents to be always positives, so be careful while
  41  * directly accessing the @size field.
  42  *
  43  * Since: 1.0
  44  **/
  45
  46
  47 #include "cpml-internal.h"
  48 #include "cpml-extents.h"
  49 #include <string.h>
  50 #include <math.h>
  51
  52
  53 /**
  54  * cpml_extents_copy:
  55  * @extents: (out): the destination #CpmlExtents
  56  * @src:     (in):  the source #CpmlExtents
  57  *
  58  * Copies @src in @extents.
  59  *
  60  * Since: 1.0
  61  **/
  62 void
  63 cpml_extents_copy(CpmlExtents *extents, const CpmlExtents *src)
  64 {
  65     memcpy(extents, src, sizeof(CpmlExtents));
  66 }
  67
  68 /**
  69  * cpml_extents_from_cairo_text:
  70  * @extents:                      (out): the destination #CpmlExtents
  71  * @cairo_extents: (in) (type gpointer): the source #cairo_text_extents_t
  72  *
  73  * Converts @cairo_extents in a #CpmlExtents format and stores the
  74  * result in @extents.
  75  *
  76  * Since: 1.0
  77  **/
  78 void
  79 cpml_extents_from_cairo_text(CpmlExtents *extents,
  80                              const cairo_text_extents_t *cairo_extents)
  81 {
  82     extents->is_defined = 1;
  83     extents->org.x = cairo_extents->x_bearing;
  84     extents->org.y = cairo_extents->y_bearing;
  85     extents->size.x = cairo_extents->width;
  86     extents->size.y = cairo_extents->height;
  87 }
  88
  89 /**
  90  * cpml_extents_equal:
  91  * @extents: the first extents to compare
  92  * @src:     the second extents to compare
  93  *
  94  * Compares @extents to @src and returns 1 if the extents are equals.
  95  * Two <constant>NULL</constant> or two undefined extents are considered equal,
  96  * although <constant>NULL</constant> extents are not equal to undefined extents.
  97  *
  98  * Returns: (type gboolean): 1 if @extents is equal to @src, 0 otherwise.
  99  *
 100  * Since: 1.0
 101  **/
 102 int
 103 cpml_extents_equal(const CpmlExtents *extents, const CpmlExtents *src)
 104 {
 105     if (extents == NULL && src == NULL)
 106         return 1;
 107
 108     if (extents == NULL || src == NULL)
 109         return 0;
 110
 111     return (!extents->is_defined && !src->is_defined) ||
 112            (extents->is_defined && src->is_defined &&
 113                cpml_pair_equal(&extents->org,  &src->org) &&
 114                cpml_pair_equal(&extents->size, &src->size));
 115 }
 116
 117 /**
 118  * cpml_extents_add:
 119  * @extents: (inout): the destination #CpmlExtents
 120  * @src:     (in):    the extents to add
 121  *
 122  * Merges @extents and @src and store the result in @extents.
 123  *
 124  * Since: 1.0
 125  **/
 126 void
 127 cpml_extents_add(CpmlExtents *extents, const CpmlExtents *src)
 128 {
 129     CpmlPair pair;
 130
 131     if (src->is_defined == 0)
 132         return;
 133
 134     pair.x = src->org.x + src->size.x;
 135     pair.y = src->org.y + src->size.y;
 136
 137     cpml_extents_pair_add(extents, &src->org);
 138     cpml_extents_pair_add(extents, &pair);
 139 }
 140
 141 /**
 142  * cpml_extents_pair_add:
 143  * @extents: (inout): the source and destination #CpmlExtents
 144  * @src:     (in):    the #CpmlPair to add
 145  *
 146  * Extends @extents, if required, to include @src. If @extents is
 147  * undefined, the origin of @extents is set to @src and its size
 148  * will be (0,0).
 149  *
 150  * Since: 1.0
 151  **/
 152 void
 153 cpml_extents_pair_add(CpmlExtents *extents, const CpmlPair *src)
 154 {
 155     if (extents->is_defined == 0) {
 156         extents->is_defined = 1;
 157         cpml_pair_copy(&extents->org, src);
 158         extents->size.x = 0;
 159         extents->size.y = 0;
 160         return;
 161     }
 162
 163     if (src->x < extents->org.x) {
 164         extents->size.x += extents->org.x - src->x;
 165         extents->org.x = src->x;
 166     } else if (src->x > extents->org.x + extents->size.x) {
 167         extents->size.x = src->x - extents->org.x;
 168     }
 169
 170     if (src->y < extents->org.y) {
 171         extents->size.y += extents->org.y - src->y;
 172         extents->org.y = src->y;
 173     } else if (src->y > extents->org.y + extents->size.y) {
 174         extents->size.y = src->y - extents->org.y;
 175     }
 176 }
 177
 178 /**
 179  * cpml_extents_is_inside:
 180  * @extents: the container #CpmlExtents
 181  * @src:     the subject #CpmlExtents
 182  *
 183  * Checks wheter @src is enterely contained by @extents. If @extents
 184  * is undefined, 0 will be returned. If @src is undefined, 1 will
 185  * be returned. The border of @extents is considered inside.
 186  *
 187  * Returns: (type gboolean): 1 if @src is totally inside @extents, 0 otherwise.
 188  *
 189  * Since: 1.0
 190  **/
 191 int
 192 cpml_extents_is_inside(const CpmlExtents *extents, const CpmlExtents *src)
 193 {
 194     CpmlPair pe, ps;
 195
 196     if (extents->is_defined == 0)
 197         return 0;
 198
 199     if (src->is_defined == 0)
 200         return 1;
 201
 202     cpml_pair_copy(&pe, &extents->org);
 203     cpml_pair_copy(&ps, &src->org);
 204
 205     if (ps.x < pe.x || ps.y < pe.y)
 206         return 0;
 207
 208     pe.x += extents->size.x;
 209     pe.y += extents->size.y;
 210     ps.x += src->size.x;
 211     ps.y += src->size.y;
 212
 213     return ps.x <= pe.x && ps.y <= pe.y;
 214 }
 215
 216 /**
 217  * cpml_extents_pair_is_inside:
 218  * @extents: the container #CpmlExtents
 219  * @src:     the subject #CpmlPair
 220  *
 221  * Checks wheter @src is inside @extents. If @extents is undefined,
 222  * 0 will be returned. The border of @extents is considered inside.
 223  *
 224  * Returns: (type gboolean): 1 if @src is inside @extents, 0 otherwise.
 225  *
 226  * Since: 1.0
 227  **/
 228 int
 229 cpml_extents_pair_is_inside(const CpmlExtents *extents, const CpmlPair *src)
 230 {
 231     if (extents->is_defined == 0 ||
 232         src->x < extents->org.x || src->y < extents->org.y ||
 233         src->x > extents->org.x + extents->size.x ||
 234         src->y > extents->org.y + extents->size.y)
 235         return 0;
 236
 237     return 1;
 238 }
 239
 240 /**
 241  * cpml_extents_transform:
 242  * @extents: (inout): the container #CpmlExtents
 243  * @matrix:  (in):    the transformation matrix
 244  *
 245  * Transforms the four corners of @extents with @matrix and
 246  * recomputes @extents. This will logically equivalent to transform
 247  * an extents box and gets the extents of the resulting shape.
 248  *
 249  * Since: 1.0
 250  **/
 251 void
 252 cpml_extents_transform(CpmlExtents *extents, const cairo_matrix_t *matrix)
 253 {
 254     CpmlPair p[4];
 255
 256     if (extents->is_defined == 0)
 257         return;
 258
 259     p[0] = extents->org;
 260     p[1].x = extents->org.x + extents->size.x;
 261     p[1].y = extents->org.y;
 262     p[2].x = extents->org.x + extents->size.x;
 263     p[2].y = extents->org.y + extents->size.y;
 264     p[3].x = extents->org.x;
 265     p[3].y = extents->org.y + extents->size.y;
 266
 267     cairo_matrix_transform_point(matrix, &p[0].x, &p[0].y);
 268     cairo_matrix_transform_point(matrix, &p[1].x, &p[1].y);
 269     cairo_matrix_transform_point(matrix, &p[2].x, &p[2].y);
 270     cairo_matrix_transform_point(matrix, &p[3].x, &p[3].y);
 271
 272     extents->is_defined = 0;
 273     cpml_extents_pair_add(extents, &p[0]);
 274     cpml_extents_pair_add(extents, &p[1]);
 275     cpml_extents_pair_add(extents, &p[2]);
 276     cpml_extents_pair_add(extents, &p[3]);
 277 }