src/adg/adg-style.c

   1 /* ADG - Automatic Drawing Generation
   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:adg-style
  23  * @short_description: The base class of all styling objects
  24  *
  25  * This is the fundamental abstract class for styles.
  26  *
  27  * Since: 1.0
  28  **/
  29
  30 /**
  31  * AdgStyle:
  32  *
  33  * All fields are private and should not be used directly.
  34  * Use its public methods instead.
  35  *
  36  * Since: 1.0
  37  **/
  38
  39 /**
  40  * AdgStyleClass:
  41  * @invalidate: virtual method to reset the style.
  42  * @apply:      abstract virtual to apply a style to a cairo context.
  43  *
  44  * The default @invalidate handler does not do anything.
  45  *
  46  * The virtual method @apply *must* be implemented by any derived class.
  47  * The default implementation will trigger an error if called.
  48  *
  49  * Since: 1.0
  50  **/
  51
  52
  53 #include "adg-internal.h"
  54
  55 #include "adg-style.h"
  56
  57
  58 #define _ADG_OLD_OBJECT_CLASS  ((GObjectClass *) adg_style_parent_class)
  59
  60
  61 G_DEFINE_ABSTRACT_TYPE(AdgStyle, adg_style, G_TYPE_OBJECT)
  62
  63 enum {
  64     INVALIDATE,
  65     APPLY,
  66     LAST_SIGNAL
  67 };
  68
  69 static void             _adg_dispose            (GObject        *object);
  70 static void             _adg_apply              (AdgStyle       *style,
  71                                                  AdgEntity      *entity,
  72                                                  cairo_t        *cr);
  73 static guint            _adg_signals[LAST_SIGNAL] = { 0 };
  74
  75
  76 static void
  77 adg_style_class_init(AdgStyleClass *klass)
  78 {
  79     GObjectClass *gobject_class;
  80
  81     gobject_class = (GObjectClass *) klass;
  82
  83     gobject_class->dispose = _adg_dispose;
  84
  85     klass->clone = (AdgStyle *(*)(AdgStyle *)) adg_object_clone;
  86     klass->invalidate = NULL;
  87     klass->apply = _adg_apply;
  88
  89     /**
  90      * AdgStyle::invalidate:
  91      * @style: an #AdgStyle
  92      *
  93      * Invalidates the @style, that is resets all the cache, if any,
  94      * retained by the internal implementation.
  95      *
  96      * This signal is emitted while disposing @style, so be sure it
  97      * can be called more than once without harms. Furthermore it
  98      * will be emitted from property setter code of new implementations
  99      * to force the recomputation of the cache.
 100      *
 101      * Since: 1.0
 102      **/
 103     _adg_signals[INVALIDATE] =
 104         g_signal_new("invalidate",
 105                      G_OBJECT_CLASS_TYPE(klass),
 106                      G_SIGNAL_RUN_LAST,
 107                      G_STRUCT_OFFSET(AdgStyleClass, invalidate),
 108                      NULL, NULL,
 109                      g_cclosure_marshal_VOID__VOID,
 110                      G_TYPE_NONE, 0);
 111
 112     /**
 113      * AdgStyle::apply:
 114      * @style: an #AdgStyle
 115      * @entity: the caller #AdgEntity
 116      * @cr: the #cairo_t context
 117      *
 118      * Applies @style to @cr so the next rendering operations will be
 119      * done accordling to this style directives. The @entity parameter
 120      * is used to resolve the internal dresses of @style, if any.
 121      *
 122      * Since: 1.0
 123      **/
 124     _adg_signals[APPLY] =
 125         g_signal_new("apply",
 126                      G_OBJECT_CLASS_TYPE(klass),
 127                      G_SIGNAL_RUN_LAST,
 128                      G_STRUCT_OFFSET(AdgStyleClass, apply),
 129                      NULL, NULL,
 130                      adg_marshal_VOID__OBJECT_POINTER,
 131                      G_TYPE_NONE, 2, ADG_TYPE_ENTITY, G_TYPE_POINTER);
 132 }
 133
 134 static void
 135 adg_style_init(AdgStyle *style)
 136 {
 137 }
 138
 139 static void
 140 _adg_dispose(GObject *object)
 141 {
 142     g_signal_emit(object, _adg_signals[INVALIDATE], 0);
 143
 144     if (_ADG_OLD_OBJECT_CLASS->dispose != NULL)
 145         _ADG_OLD_OBJECT_CLASS->dispose(object);
 146 }
 147
 148
 149 /**
 150  * adg_style_invalidate:
 151  * @style: an #AdgStyle derived style
 152  *
 153  * Emits the #AdgStyle::invalidate signal on @style. This signal
 154  * is always emitted while disposing @style, so be sure it
 155  * can be called more than once without harms.
 156  *
 157  * <note><para>
 158  * This function is only useful in new style implementations.
 159  * </para></note>
 160  *
 161  * Since: 1.0
 162  **/
 163 void
 164 adg_style_invalidate(AdgStyle *style)
 165 {
 166     g_return_if_fail(ADG_IS_STYLE(style));
 167
 168     g_signal_emit(style, _adg_signals[INVALIDATE], 0);
 169 }
 170
 171 /**
 172  * adg_style_clone:
 173  * @style: (transfer none): an #AdgStyle derived style
 174  *
 175  * Clones @style. Useful for customizing styles.
 176  *
 177  * Returns: (transfer full): a newly created style.
 178  *
 179  * Since: 1.0
 180  **/
 181 AdgStyle *
 182 adg_style_clone(AdgStyle *style)
 183 {
 184     AdgStyleClass *klass;
 185
 186     g_return_val_if_fail(ADG_IS_STYLE(style), NULL);
 187
 188     klass = ADG_STYLE_GET_CLASS(style);
 189
 190     if (klass->clone == NULL)
 191         return NULL;
 192
 193     return klass->clone(style);
 194 }
 195
 196 /**
 197  * adg_style_apply:
 198  * @style: an #AdgStyle derived style
 199  * @entity: the caller #AdgEntity
 200  * @cr: the subject cairo context
 201  *
 202  * Emits the #AdgStyle::apply signal on @style, passing @entity and
 203  * @cr as parameters to the signal.
 204  *
 205  * Since: 1.0
 206  **/
 207 void
 208 adg_style_apply(AdgStyle *style, AdgEntity *entity, cairo_t *cr)
 209 {
 210     g_return_if_fail(ADG_IS_STYLE(style));
 211     g_return_if_fail(ADG_IS_ENTITY(entity));
 212     g_return_if_fail(cr != NULL);
 213
 214     g_signal_emit(style, _adg_signals[APPLY], 0, entity, cr);
 215 }
 216
 217
 218 static void
 219 _adg_apply(AdgStyle *style, AdgEntity *entity, cairo_t *cr)
 220 {
 221     /* The apply method must be defined */
 222     g_warning(_("%s: 'apply' method not implemented for type '%s'"),
 223               G_STRLOC, g_type_name(G_OBJECT_TYPE(style)));
 224 }