adg/adg-path.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 Library 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  * Library 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., 59 Temple Place - Suite 330,
  17  * Boston, MA  02111-1307, USA.
  18  */
  19
  20 /**
  21  * SECTION:path
  22  * @title: AdgPath
  23  * @short_description: A stroked path entity
  24  *
  25  * The #AdgPath object is probably the simplest entity: it represents a path
  26  * (as intended by the #cairo_path_t structure) in model space.
  27  **/
  28
  29 #include "adg-path.h"
  30 #include "adg-path-private.h"
  31 #include "adg-line-style.h"
  32 #include "adg-intl.h"
  33
  34 #define PARENT_CLASS ((AdgEntityClass *) adg_path_parent_class)
  35
  36
  37 static void     finalize                (GObject        *object);
  38 static void     invalidate              (AdgEntity      *entity);
  39 static void     render                  (AdgEntity      *entity,
  40                                          cairo_t        *cr);
  41 static void     clear_path_cache        (AdgPath        *path);
  42
  43
  44 G_DEFINE_TYPE(AdgPath, adg_path, ADG_TYPE_ENTITY)
  45
  46
  47 static void
  48 adg_path_class_init(AdgPathClass *klass)
  49 {
  50     GObjectClass *gobject_class;
  51     AdgEntityClass *entity_class;
  52
  53     gobject_class = (GObjectClass *) klass;
  54     entity_class = (AdgEntityClass *) klass;
  55
  56     g_type_class_add_private(klass, sizeof(AdgPathPrivate));
  57
  58     gobject_class->finalize = finalize;
  59
  60     entity_class->invalidate = invalidate;
  61     entity_class->render = render;
  62 }
  63
  64 static void
  65 adg_path_init(AdgPath *path)
  66 {
  67     AdgPathPrivate *priv = G_TYPE_INSTANCE_GET_PRIVATE(path, ADG_TYPE_PATH,
  68                                                        AdgPathPrivate);
  69
  70     priv->cp.x = priv->cp.y = 0.;
  71     priv->cairo_path = NULL;
  72     priv->callback = NULL;
  73
  74     path->priv = priv;
  75 }
  76
  77 static void
  78 finalize(GObject *object)
  79 {
  80     clear_path_cache((AdgPath *) object);
  81
  82     ((GObjectClass *) PARENT_CLASS)->finalize(object);
  83 }
  84
  85 /**
  86  * adg_path_new:
  87  * @callback: an #AdgCallback callback
  88  * @user_data: user provided pointer to pass to the callback
  89  *
  90  * Creates a new path entity. The path must be constructed in the @callback
  91  * function: AdgPath will cache and reuse the cairo_copy_path() returned by
  92  * the cairo context after the @callback call.
  93  *
  94  * Return value: the new entity
  95  **/
  96 AdgEntity *
  97 adg_path_new(AdgCallback callback, gpointer user_data)
  98 {
  99     AdgPath *path;
 100
 101     path = (AdgPath *) g_object_new(ADG_TYPE_PATH, NULL);
 102     path->priv->callback = callback;
 103     path->priv->user_data = user_data;
 104
 105     return (AdgEntity *) path;
 106 }
 107
 108 /**
 109  * adg_path_get_cairo_path:
 110  * @path: an #AdgPath
 111  *
 112  * Gets a pointer to the cairo path structure of @path. The return value
 113  * is owned by @path and must be considered read-only.
 114  *
 115  * Return value: a pointer to the internal #cairo_path_t structure
 116  **/
 117 const cairo_path_t *
 118 adg_path_get_cairo_path(AdgPath *path)
 119 {
 120     g_return_val_if_fail(ADG_IS_PATH(path), NULL);
 121
 122     return path->priv->cairo_path;
 123 }
 124
 125 /**
 126  * adg_path_dump:
 127  * @path: an #AdgPath
 128  *
 129  * Dumps the data content of @path to stdout in a human readable format.
 130  **/
 131 void
 132 adg_path_dump(AdgPath *path)
 133 {
 134     CpmlSegment segment;
 135
 136     g_return_if_fail(ADG_IS_PATH(path));
 137
 138     if (!cpml_segment_from_cairo(&segment, path->priv->cairo_path)) {
 139         g_print("Invalid path data to dump!\n");
 140     } else {
 141         do {
 142             cpml_segment_dump(&segment);
 143         } while (cpml_segment_next(&segment));
 144     }
 145 }
 146
 147 static void
 148 invalidate(AdgEntity *entity)
 149 {
 150     clear_path_cache((AdgPath *) entity);
 151
 152     PARENT_CLASS->invalidate(entity);
 153 }
 154
 155 static void
 156 render(AdgEntity *entity, cairo_t *cr)
 157 {
 158     AdgPath *path = (AdgPath *) entity;
 159
 160     if (path->priv->cairo_path) {
 161         /* Use cached data */
 162         cairo_move_to(cr, path->priv->cp.x, path->priv->cp.y);
 163         cairo_append_path(cr, path->priv->cairo_path);
 164     } else {
 165         /* Construct and store the cache */
 166         cairo_get_current_point(cr, &path->priv->cp.x, &path->priv->cp.y);
 167
 168         if (path->priv->callback)
 169             path->priv->callback(entity, cr, path->priv->user_data);
 170
 171         path->priv->cairo_path = cairo_copy_path(cr);
 172     }
 173
 174     adg_entity_apply(entity, ADG_SLOT_LINE_STYLE, cr);
 175     cairo_stroke(cr);
 176
 177     PARENT_CLASS->render(entity, cr);
 178 }
 179
 180 static void
 181 clear_path_cache(AdgPath *path)
 182 {
 183     AdgPathPrivate *priv = path->priv;
 184
 185     if (priv->cairo_path != NULL) {
 186         cairo_path_destroy(priv->cairo_path);
 187         priv->cairo_path = NULL;
 188     }
 189
 190     priv->cp.x = priv->cp.y = 0.;
 191 }