src/adg/adg-style.c

   1 /* ADG - Automatic Drawing Generation
   2  * Copyright (C) 2007,2008,2009,2010,2011,2012,2013  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->invalidate = NULL;
  86     klass->apply = _adg_apply;
  87
  88     /**
  89      * AdgStyle::invalidate:
  90      * @style: an #AdgStyle
  91      *
  92      * Invalidates the @style, that is resets all the cache, if any,
  93      * retained by the internal implementation.
  94      *
  95      * This signal is emitted while disposing @style, so be sure it
  96      * can be called more than once without harms. Furthermore it
  97      * will be emitted from property setter code of new implementations
  98      * to force the recomputation of the cache.
  99      *
 100      * Since: 1.0
 101      **/
 102     _adg_signals[INVALIDATE] =
 103         g_signal_new("invalidate",
 104                      G_OBJECT_CLASS_TYPE(klass),
 105                      G_SIGNAL_RUN_LAST,
 106                      G_STRUCT_OFFSET(AdgStyleClass, invalidate),
 107                      NULL, NULL,
 108                      adg_marshal_VOID__VOID,
 109                      G_TYPE_NONE, 0);
 110
 111     /**
 112      * AdgStyle::apply:
 113      * @style: an #AdgStyle
 114      * @entity: the caller #AdgEntity
 115      * @cr: the #cairo_t context
 116      *
 117      * Applies @style to @cr so the next rendering operations will be
 118      * done accordling to this style directives. The @entity parameter
 119      * is used to resolve the internal dresses of @style, if any.
 120      *
 121      * Since: 1.0
 122      **/
 123     _adg_signals[APPLY] =
 124         g_signal_new("apply",
 125                      G_OBJECT_CLASS_TYPE(klass),
 126                      G_SIGNAL_RUN_LAST,
 127                      G_STRUCT_OFFSET(AdgStyleClass, apply),
 128                      NULL, NULL,
 129                      adg_marshal_VOID__OBJECT_POINTER,
 130                      G_TYPE_NONE, 2, ADG_TYPE_ENTITY, G_TYPE_POINTER);
 131 }
 132
 133 static void
 134 adg_style_init(AdgStyle *style)
 135 {
 136 }
 137
 138 static void
 139 _adg_dispose(GObject *object)
 140 {
 141     g_signal_emit(object, _adg_signals[INVALIDATE], 0);
 142
 143     if (_ADG_OLD_OBJECT_CLASS->dispose != NULL)
 144         _ADG_OLD_OBJECT_CLASS->dispose(object);
 145 }
 146
 147
 148 /**
 149  * adg_style_invalidate:
 150  * @style: an #AdgStyle derived style
 151  *
 152  * Emits the #AdgStyle::invalidate signal on @style. This signal
 153  * is always emitted while disposing @style, so be sure it
 154  * can be called more than once without harms.
 155  *
 156  * <note><para>
 157  * This function is only useful in new style implementations.
 158  * </para></note>
 159  *
 160  * Since: 1.0
 161  **/
 162 void
 163 adg_style_invalidate(AdgStyle *style)
 164 {
 165     g_return_if_fail(ADG_IS_STYLE(style));
 166
 167     g_signal_emit(style, _adg_signals[INVALIDATE], 0);
 168 }
 169
 170 /**
 171  * adg_style_apply:
 172  * @style: an #AdgStyle derived style
 173  * @entity: the caller #AdgEntity
 174  * @cr: the subject cairo context
 175  *
 176  * Emits the #AdgStyle::apply signal on @style, passing @entity and
 177  * @cr as parameters to the signal.
 178  *
 179  * Since: 1.0
 180  **/
 181 void
 182 adg_style_apply(AdgStyle *style, AdgEntity *entity, cairo_t *cr)
 183 {
 184     g_return_if_fail(ADG_IS_STYLE(style));
 185     g_return_if_fail(ADG_IS_ENTITY(entity));
 186     g_return_if_fail(cr != NULL);
 187
 188     g_signal_emit(style, _adg_signals[APPLY], 0, entity, cr);
 189 }
 190
 191
 192 static void
 193 _adg_apply(AdgStyle *style, AdgEntity *entity, cairo_t *cr)
 194 {
 195     /* The apply method must be defined */
 196     g_warning(_("%s: `apply' method not implemented for type `%s'"),
 197               G_STRLOC, g_type_name(G_OBJECT_TYPE(style)));
 198 }