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glib/gobject/gbinding.c

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/* gbinding.c: Binding for object properties
*
* Copyright (C) 2010 Intel Corp.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: Emmanuele Bassi <ebassi@linux.intel.com>
*/
/**
* SECTION:gbinding
* @Title: GBinding
* @Short_Description: Bind two object properties
*
* #GBinding is the representation of a binding between a property on a
* #GObject instance (or source) and another property on another #GObject
* instance (or target). Whenever the source property changes, the same
* value is applied to the target property; for instance, the following
* binding:
*
* |[<!-- language="C" -->
* g_object_bind_property (object1, "property-a",
* object2, "property-b",
* G_BINDING_DEFAULT);
* ]|
*
* will cause the property named "property-b" of @object2 to be updated
* every time g_object_set() or the specific accessor changes the value of
* the property "property-a" of @object1.
*
* It is possible to create a bidirectional binding between two properties
* of two #GObject instances, so that if either property changes, the
* other is updated as well, for instance:
*
* |[<!-- language="C" -->
* g_object_bind_property (object1, "property-a",
* object2, "property-b",
* G_BINDING_BIDIRECTIONAL);
* ]|
*
* will keep the two properties in sync.
*
* It is also possible to set a custom transformation function (in both
* directions, in case of a bidirectional binding) to apply a custom
* transformation from the source value to the target value before
* applying it; for instance, the following binding:
*
* |[<!-- language="C" -->
* g_object_bind_property_full (adjustment1, "value",
* adjustment2, "value",
* G_BINDING_BIDIRECTIONAL,
* celsius_to_fahrenheit,
* fahrenheit_to_celsius,
* NULL, NULL);
* ]|
*
* will keep the "value" property of the two adjustments in sync; the
* @celsius_to_fahrenheit function will be called whenever the "value"
* property of @adjustment1 changes and will transform the current value
* of the property before applying it to the "value" property of @adjustment2.
*
* Vice versa, the @fahrenheit_to_celsius function will be called whenever
* the "value" property of @adjustment2 changes, and will transform the
* current value of the property before applying it to the "value" property
* of @adjustment1.
*
* Note that #GBinding does not resolve cycles by itself; a cycle like
*
* |[
* object1:propertyA -> object2:propertyB
* object2:propertyB -> object3:propertyC
* object3:propertyC -> object1:propertyA
* ]|
*
* might lead to an infinite loop. The loop, in this particular case,
* can be avoided if the objects emit the #GObject::notify signal only
* if the value has effectively been changed. A binding is implemented
* using the #GObject::notify signal, so it is susceptible to all the
* various ways of blocking a signal emission, like g_signal_stop_emission()
* or g_signal_handler_block().
*
* A binding will be severed, and the resources it allocates freed, whenever
* either one of the #GObject instances it refers to are finalized, or when
* the #GBinding instance loses its last reference.
*
* Bindings for languages with garbage collection can use
* g_binding_unbind() to explicitly release a binding between the source
* and target properties, instead of relying on the last reference on the
* binding, source, and target instances to drop.
*
* #GBinding is available since GObject 2.26
*/
#include "config.h"
#include <string.h>
#include "gbinding.h"
#include "genums.h"
#include "gmarshal.h"
#include "gobject.h"
#include "gsignal.h"
#include "gparamspecs.h"
#include "gvaluetypes.h"
#include "glibintl.h"
GType
g_binding_flags_get_type (void)
{
static volatile gsize g_define_type_id__volatile = 0;
if (g_once_init_enter (&g_define_type_id__volatile))
{
static const GFlagsValue values[] = {
{ G_BINDING_DEFAULT, "G_BINDING_DEFAULT", "default" },
{ G_BINDING_BIDIRECTIONAL, "G_BINDING_BIDIRECTIONAL", "bidirectional" },
{ G_BINDING_SYNC_CREATE, "G_BINDING_SYNC_CREATE", "sync-create" },
{ G_BINDING_INVERT_BOOLEAN, "G_BINDING_INVERT_BOOLEAN", "invert-boolean" },
{ 0, NULL, NULL }
};
GType g_define_type_id =
g_flags_register_static (g_intern_static_string ("GBindingFlags"), values);
g_once_init_leave (&g_define_type_id__volatile, g_define_type_id);
}
return g_define_type_id__volatile;
}
#define G_BINDING_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), G_TYPE_BINDING, GBindingClass))
#define G_IS_BINDING_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), G_TYPE_BINDING))
#define G_BINDING_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), G_TYPE_BINDING, GBindingClass))
typedef struct _GBindingClass GBindingClass;
struct _GBinding
{
GObject parent_instance;
/* no reference is held on the objects, to avoid cycles */
GObject *source;
GObject *target;
/* the property names are interned, so they should not be freed */
const gchar *source_property;
const gchar *target_property;
GParamSpec *source_pspec;
GParamSpec *target_pspec;
GBindingTransformFunc transform_s2t;
GBindingTransformFunc transform_t2s;
GBindingFlags flags;
guint source_notify;
guint target_notify;
gpointer transform_data;
GDestroyNotify notify;
/* a guard, to avoid loops */
guint is_frozen : 1;
};
struct _GBindingClass
{
GObjectClass parent_class;
};
enum
{
PROP_0,
PROP_SOURCE,
PROP_TARGET,
PROP_SOURCE_PROPERTY,
PROP_TARGET_PROPERTY,
PROP_FLAGS
};
static guint gobject_notify_signal_id;
G_DEFINE_TYPE (GBinding, g_binding, G_TYPE_OBJECT);
/* the basic assumption is that if either the source or the target
* goes away then the binding does not exist any more and it should
* be reaped as well
*/
static void
weak_unbind (gpointer user_data,
GObject *where_the_object_was)
{
GBinding *binding = user_data;
/* if what went away was the source, unset it so that GBinding::finalize
* does not try to access it; otherwise, disconnect everything and remove
* the GBinding instance from the object's qdata
*/
if (binding->source == where_the_object_was)
binding->source = NULL;
else
{
if (binding->source_notify != 0)
g_signal_handler_disconnect (binding->source, binding->source_notify);
g_object_weak_unref (binding->source, weak_unbind, user_data);
binding->source_notify = 0;
binding->source = NULL;
}
/* as above, but with the target */
if (binding->target == where_the_object_was)
binding->target = NULL;
else
{
if (binding->target_notify != 0)
g_signal_handler_disconnect (binding->target, binding->target_notify);
g_object_weak_unref (binding->target, weak_unbind, user_data);
binding->target_notify = 0;
binding->target = NULL;
}
/* this will take care of the binding itself */
g_object_unref (binding);
}
static gboolean
default_transform (GBinding *binding,
const GValue *value_a,
GValue *value_b,
gpointer user_data G_GNUC_UNUSED)
{
/* if it's not the same type, try to convert it using the GValue
* transformation API; otherwise just copy it
*/
if (!g_type_is_a (G_VALUE_TYPE (value_a), G_VALUE_TYPE (value_b)))
{
/* are these two types compatible (can be directly copied)? */
if (g_value_type_compatible (G_VALUE_TYPE (value_a),
G_VALUE_TYPE (value_b)))
{
g_value_copy (value_a, value_b);
return TRUE;
}
if (g_value_type_transformable (G_VALUE_TYPE (value_a),
G_VALUE_TYPE (value_b)))
{
if (g_value_transform (value_a, value_b))
return TRUE;
}
g_warning ("%s: Unable to convert a value of type %s to a "
"value of type %s",
G_STRLOC,
g_type_name (G_VALUE_TYPE (value_a)),
g_type_name (G_VALUE_TYPE (value_b)));
return FALSE;
}
g_value_copy (value_a, value_b);
return TRUE;
}
static gboolean
default_invert_boolean_transform (GBinding *binding,
const GValue *value_a,
GValue *value_b,
gpointer user_data G_GNUC_UNUSED)
{
gboolean value;
g_assert (G_VALUE_HOLDS_BOOLEAN (value_a));
g_assert (G_VALUE_HOLDS_BOOLEAN (value_b));
value = g_value_get_boolean (value_a);
value = !value;
g_value_set_boolean (value_b, value);
return TRUE;
}
static void
on_source_notify (GObject *gobject,
GParamSpec *pspec,
GBinding *binding)
{
GValue from_value = G_VALUE_INIT;
GValue to_value = G_VALUE_INIT;
gboolean res;
if (binding->is_frozen)
return;
g_value_init (&from_value, G_PARAM_SPEC_VALUE_TYPE (binding->source_pspec));
g_value_init (&to_value, G_PARAM_SPEC_VALUE_TYPE (binding->target_pspec));
g_object_get_property (binding->source, binding->source_pspec->name, &from_value);
res = binding->transform_s2t (binding,
&from_value,
&to_value,
binding->transform_data);
if (res)
{
binding->is_frozen = TRUE;
g_param_value_validate (binding->target_pspec, &to_value);
g_object_set_property (binding->target, binding->target_pspec->name, &to_value);
binding->is_frozen = FALSE;
}
g_value_unset (&from_value);
g_value_unset (&to_value);
}
static void
on_target_notify (GObject *gobject,
GParamSpec *pspec,
GBinding *binding)
{
GValue from_value = G_VALUE_INIT;
GValue to_value = G_VALUE_INIT;
gboolean res;
if (binding->is_frozen)
return;
g_value_init (&from_value, G_PARAM_SPEC_VALUE_TYPE (binding->target_pspec));
g_value_init (&to_value, G_PARAM_SPEC_VALUE_TYPE (binding->source_pspec));
g_object_get_property (binding->target, binding->target_pspec->name, &from_value);
res = binding->transform_t2s (binding,
&from_value,
&to_value,
binding->transform_data);
if (res)
{
binding->is_frozen = TRUE;
g_param_value_validate (binding->source_pspec, &to_value);
g_object_set_property (binding->source, binding->source_pspec->name, &to_value);
binding->is_frozen = FALSE;
}
g_value_unset (&from_value);
g_value_unset (&to_value);
}
static inline void
g_binding_unbind_internal (GBinding *binding,
gboolean unref_binding)
{
gboolean source_is_target = binding->source == binding->target;
/* dispose of the transformation data */
if (binding->notify != NULL)
{
binding->notify (binding->transform_data);
binding->transform_data = NULL;
binding->notify = NULL;
}
if (binding->source != NULL)
{
if (binding->source_notify != 0)
g_signal_handler_disconnect (binding->source, binding->source_notify);
g_object_weak_unref (binding->source, weak_unbind, binding);
binding->source_notify = 0;
binding->source = NULL;
}
if (binding->target != NULL)
{
if (binding->target_notify != 0)
g_signal_handler_disconnect (binding->target, binding->target_notify);
if (!source_is_target)
g_object_weak_unref (binding->target, weak_unbind, binding);
binding->target_notify = 0;
binding->target = NULL;
}
if (unref_binding)
g_object_unref (binding);
}
static void
g_binding_finalize (GObject *gobject)
{
GBinding *binding = G_BINDING (gobject);
g_binding_unbind_internal (binding, FALSE);
G_OBJECT_CLASS (g_binding_parent_class)->finalize (gobject);
}
static void
g_binding_set_property (GObject *gobject,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GBinding *binding = G_BINDING (gobject);
switch (prop_id)
{
case PROP_SOURCE:
binding->source = g_value_get_object (value);
break;
case PROP_SOURCE_PROPERTY:
binding->source_property = g_intern_string (g_value_get_string (value));
break;
case PROP_TARGET:
binding->target = g_value_get_object (value);
break;
case PROP_TARGET_PROPERTY:
binding->target_property = g_intern_string (g_value_get_string (value));
break;
case PROP_FLAGS:
binding->flags = g_value_get_flags (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
static void
g_binding_get_property (GObject *gobject,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GBinding *binding = G_BINDING (gobject);
switch (prop_id)
{
case PROP_SOURCE:
g_value_set_object (value, binding->source);
break;
case PROP_SOURCE_PROPERTY:
g_value_set_string (value, binding->source_property);
break;
case PROP_TARGET:
g_value_set_object (value, binding->target);
break;
case PROP_TARGET_PROPERTY:
g_value_set_string (value, binding->target_property);
break;
case PROP_FLAGS:
g_value_set_flags (value, binding->flags);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
static void
g_binding_constructed (GObject *gobject)
{
GBinding *binding = G_BINDING (gobject);
GBindingTransformFunc transform_func = default_transform;
GQuark source_property_detail;
GClosure *source_notify_closure;
/* assert that we were constructed correctly */
g_assert (binding->source != NULL);
g_assert (binding->target != NULL);
g_assert (binding->source_property != NULL);
g_assert (binding->target_property != NULL);
/* we assume a check was performed prior to construction - since
* g_object_bind_property_full() does it; we cannot fail construction
* anyway, so it would be hard for use to properly warn here
*/
binding->source_pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (binding->source), binding->source_property);
binding->target_pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (binding->target), binding->target_property);
g_assert (binding->source_pspec != NULL);
g_assert (binding->target_pspec != NULL);
/* switch to the invert boolean transform if needed */
if (binding->flags & G_BINDING_INVERT_BOOLEAN)
transform_func = default_invert_boolean_transform;
/* set the default transformation functions here */
binding->transform_s2t = transform_func;
binding->transform_t2s = transform_func;
binding->transform_data = NULL;
binding->notify = NULL;
source_property_detail = g_quark_from_string (binding->source_property);
source_notify_closure = g_cclosure_new (G_CALLBACK (on_source_notify),
binding, NULL);
binding->source_notify = g_signal_connect_closure_by_id (binding->source,
gobject_notify_signal_id,
source_property_detail,
source_notify_closure,
FALSE);
g_object_weak_ref (binding->source, weak_unbind, binding);
if (binding->flags & G_BINDING_BIDIRECTIONAL)
{
GQuark target_property_detail;
GClosure *target_notify_closure;
target_property_detail = g_quark_from_string (binding->target_property);
target_notify_closure = g_cclosure_new (G_CALLBACK (on_target_notify),
binding, NULL);
binding->target_notify = g_signal_connect_closure_by_id (binding->target,
gobject_notify_signal_id,
target_property_detail,
target_notify_closure,
FALSE);
}
if (binding->target != binding->source)
g_object_weak_ref (binding->target, weak_unbind, binding);
}
static void
g_binding_class_init (GBindingClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_notify_signal_id = g_signal_lookup ("notify", G_TYPE_OBJECT);
g_assert (gobject_notify_signal_id != 0);
gobject_class->constructed = g_binding_constructed;
gobject_class->set_property = g_binding_set_property;
gobject_class->get_property = g_binding_get_property;
gobject_class->finalize = g_binding_finalize;
/**
* GBinding:source:
*
* The #GObject that should be used as the source of the binding
*
* Since: 2.26
*/
g_object_class_install_property (gobject_class, PROP_SOURCE,
g_param_spec_object ("source",
P_("Source"),
P_("The source of the binding"),
G_TYPE_OBJECT,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
/**
* GBinding:target:
*
* The #GObject that should be used as the target of the binding
*
* Since: 2.26
*/
g_object_class_install_property (gobject_class, PROP_TARGET,
g_param_spec_object ("target",
P_("Target"),
P_("The target of the binding"),
G_TYPE_OBJECT,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
/**
* GBinding:source-property:
*
* The name of the property of #GBinding:source that should be used
* as the source of the binding
*
* Since: 2.26
*/
g_object_class_install_property (gobject_class, PROP_SOURCE_PROPERTY,
g_param_spec_string ("source-property",
P_("Source Property"),
P_("The property on the source to bind"),
NULL,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
/**
* GBinding:target-property:
*
* The name of the property of #GBinding:target that should be used
* as the target of the binding
*
* Since: 2.26
*/
g_object_class_install_property (gobject_class, PROP_TARGET_PROPERTY,
g_param_spec_string ("target-property",
P_("Target Property"),
P_("The property on the target to bind"),
NULL,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
/**
* GBinding:flags:
*
* Flags to be used to control the #GBinding
*
* Since: 2.26
*/
g_object_class_install_property (gobject_class, PROP_FLAGS,
g_param_spec_flags ("flags",
P_("Flags"),
P_("The binding flags"),
G_TYPE_BINDING_FLAGS,
G_BINDING_DEFAULT,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
}
static void
g_binding_init (GBinding *binding)
{
}
/**
* g_binding_get_flags:
* @binding: a #GBinding
*
* Retrieves the flags passed when constructing the #GBinding.
*
* Returns: the #GBindingFlags used by the #GBinding
*
* Since: 2.26
*/
GBindingFlags
g_binding_get_flags (GBinding *binding)
{
g_return_val_if_fail (G_IS_BINDING (binding), G_BINDING_DEFAULT);
return binding->flags;
}
/**
* g_binding_get_source:
* @binding: a #GBinding
*
* Retrieves the #GObject instance used as the source of the binding.
*
* Returns: (transfer none): the source #GObject
*
* Since: 2.26
*/
GObject *
g_binding_get_source (GBinding *binding)
{
g_return_val_if_fail (G_IS_BINDING (binding), NULL);
return binding->source;
}
/**
* g_binding_get_target:
* @binding: a #GBinding
*
* Retrieves the #GObject instance used as the target of the binding.
*
* Returns: (transfer none): the target #GObject
*
* Since: 2.26
*/
GObject *
g_binding_get_target (GBinding *binding)
{
g_return_val_if_fail (G_IS_BINDING (binding), NULL);
return binding->target;
}
/**
* g_binding_get_source_property:
* @binding: a #GBinding
*
* Retrieves the name of the property of #GBinding:source used as the source
* of the binding.
*
* Returns: the name of the source property
*
* Since: 2.26
*/
const gchar *
g_binding_get_source_property (GBinding *binding)
{
g_return_val_if_fail (G_IS_BINDING (binding), NULL);
return binding->source_property;
}
/**
* g_binding_get_target_property:
* @binding: a #GBinding
*
* Retrieves the name of the property of #GBinding:target used as the target
* of the binding.
*
* Returns: the name of the target property
*
* Since: 2.26
*/
const gchar *
g_binding_get_target_property (GBinding *binding)
{
g_return_val_if_fail (G_IS_BINDING (binding), NULL);
return binding->target_property;
}
/**
* g_binding_unbind:
* @binding: a #GBinding
*
* Explicitly releases the binding between the source and the target
* property expressed by @binding.
*
* This function will release the reference that is being held on
* the @binding instance; if you want to hold on to the #GBinding instance
* after calling g_binding_unbind(), you will need to hold a reference
* to it.
*
* Since: 2.38
*/
void
g_binding_unbind (GBinding *binding)
{
g_return_if_fail (G_IS_BINDING (binding));
g_binding_unbind_internal (binding, TRUE);
}
/**
* g_object_bind_property_full:
* @source: (type GObject.Object): the source #GObject
* @source_property: the property on @source to bind
* @target: (type GObject.Object): the target #GObject
* @target_property: the property on @target to bind
* @flags: flags to pass to #GBinding
* @transform_to: (scope notified) (allow-none): the transformation function
* from the @source to the @target, or %NULL to use the default
* @transform_from: (scope notified) (allow-none): the transformation function
* from the @target to the @source, or %NULL to use the default
* @user_data: custom data to be passed to the transformation functions,
* or %NULL
* @notify: function to be called when disposing the binding, to free the
* resources used by the transformation functions
*
* Complete version of g_object_bind_property().
*
* Creates a binding between @source_property on @source and @target_property
* on @target, allowing you to set the transformation functions to be used by
* the binding.
*
* If @flags contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual:
* if @target_property on @target changes then the @source_property on @source
* will be updated as well. The @transform_from function is only used in case
* of bidirectional bindings, otherwise it will be ignored
*
* The binding will automatically be removed when either the @source or the
* @target instances are finalized. To remove the binding without affecting the
* @source and the @target you can just call g_object_unref() on the returned
* #GBinding instance.
*
* A #GObject can have multiple bindings.
*
* The same @user_data parameter will be used for both @transform_to
* and @transform_from transformation functions; the @notify function will
* be called once, when the binding is removed. If you need different data
* for each transformation function, please use
* g_object_bind_property_with_closures() instead.
*
* Returns: (transfer none): the #GBinding instance representing the
* binding between the two #GObject instances. The binding is released
* whenever the #GBinding reference count reaches zero.
*
* Since: 2.26
*/
GBinding *
g_object_bind_property_full (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags,
GBindingTransformFunc transform_to,
GBindingTransformFunc transform_from,
gpointer user_data,
GDestroyNotify notify)
{
GParamSpec *pspec;
GBinding *binding;
g_return_val_if_fail (G_IS_OBJECT (source), NULL);
g_return_val_if_fail (source_property != NULL, NULL);
g_return_val_if_fail (G_IS_OBJECT (target), NULL);
g_return_val_if_fail (target_property != NULL, NULL);
if (source == target && g_strcmp0 (source_property, target_property) == 0)
{
g_warning ("Unable to bind the same property on the same instance");
return NULL;
}
/* remove the G_BINDING_INVERT_BOOLEAN flag in case we have
* custom transformation functions
*/
if ((flags & G_BINDING_INVERT_BOOLEAN) &&
(transform_to != NULL || transform_from != NULL))
{
flags &= ~G_BINDING_INVERT_BOOLEAN;
}
pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (source), source_property);
if (pspec == NULL)
{
g_warning ("%s: The source object of type %s has no property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (source),
source_property);
return NULL;
}
if (!(pspec->flags & G_PARAM_READABLE))
{
g_warning ("%s: The source object of type %s has no readable property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (source),
source_property);
return NULL;
}
if ((flags & G_BINDING_BIDIRECTIONAL) &&
((pspec->flags & G_PARAM_CONSTRUCT_ONLY) || !(pspec->flags & G_PARAM_WRITABLE)))
{
g_warning ("%s: The source object of type %s has no writable property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (source),
source_property);
return NULL;
}
if ((flags & G_BINDING_INVERT_BOOLEAN) &&
!(G_PARAM_SPEC_VALUE_TYPE (pspec) == G_TYPE_BOOLEAN))
{
g_warning ("%s: The G_BINDING_INVERT_BOOLEAN flag can only be used "
"when binding boolean properties; the source property '%s' "
"is of type '%s'",
G_STRLOC,
source_property,
g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
return NULL;
}
pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (target), target_property);
if (pspec == NULL)
{
g_warning ("%s: The target object of type %s has no property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (target),
target_property);
return NULL;
}
if ((pspec->flags & G_PARAM_CONSTRUCT_ONLY) || !(pspec->flags & G_PARAM_WRITABLE))
{
g_warning ("%s: The target object of type %s has no writable property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (target),
target_property);
return NULL;
}
if ((flags & G_BINDING_BIDIRECTIONAL) &&
!(pspec->flags & G_PARAM_READABLE))
{
g_warning ("%s: The target object of type %s has no readable property called '%s'",
G_STRLOC,
G_OBJECT_TYPE_NAME (target),
target_property);
return NULL;
}
if ((flags & G_BINDING_INVERT_BOOLEAN) &&
!(G_PARAM_SPEC_VALUE_TYPE (pspec) == G_TYPE_BOOLEAN))
{
g_warning ("%s: The G_BINDING_INVERT_BOOLEAN flag can only be used "
"when binding boolean properties; the target property '%s' "
"is of type '%s'",
G_STRLOC,
target_property,
g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
return NULL;
}
binding = g_object_new (G_TYPE_BINDING,
"source", source,
"source-property", source_property,
"target", target,
"target-property", target_property,
"flags", flags,
NULL);
if (transform_to != NULL)
binding->transform_s2t = transform_to;
if (transform_from != NULL)
binding->transform_t2s = transform_from;
binding->transform_data = user_data;
binding->notify = notify;
/* synchronize the target with the source by faking an emission of
* the ::notify signal for the source property; this will also take
* care of the bidirectional binding case because the eventual change
* will emit a notification on the target
*/
if (flags & G_BINDING_SYNC_CREATE)
on_source_notify (binding->source, binding->source_pspec, binding);
return binding;
}
/**
* g_object_bind_property:
* @source: (type GObject.Object): the source #GObject
* @source_property: the property on @source to bind
* @target: (type GObject.Object): the target #GObject
* @target_property: the property on @target to bind
* @flags: flags to pass to #GBinding
*
* Creates a binding between @source_property on @source and @target_property
* on @target. Whenever the @source_property is changed the @target_property is
* updated using the same value. For instance:
*
* |[
* g_object_bind_property (action, "active", widget, "sensitive", 0);
* ]|
*
* Will result in the "sensitive" property of the widget #GObject instance to be
* updated with the same value of the "active" property of the action #GObject
* instance.
*
* If @flags contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual:
* if @target_property on @target changes then the @source_property on @source
* will be updated as well.
*
* The binding will automatically be removed when either the @source or the
* @target instances are finalized. To remove the binding without affecting the
* @source and the @target you can just call g_object_unref() on the returned
* #GBinding instance.
*
* A #GObject can have multiple bindings.
*
* Returns: (transfer none): the #GBinding instance representing the
* binding between the two #GObject instances. The binding is released
* whenever the #GBinding reference count reaches zero.
*
* Since: 2.26
*/
GBinding *
g_object_bind_property (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags)
{
/* type checking is done in g_object_bind_property_full() */
return g_object_bind_property_full (source, source_property,
target, target_property,
flags,
NULL,
NULL,
NULL, NULL);
}
typedef struct _TransformData
{
GClosure *transform_to_closure;
GClosure *transform_from_closure;
} TransformData;
static gboolean
bind_with_closures_transform_to (GBinding *binding,
const GValue *source,
GValue *target,
gpointer data)
{
TransformData *t_data = data;
GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };
GValue retval = G_VALUE_INIT;
gboolean res;
g_value_init (&params[0], G_TYPE_BINDING);
g_value_set_object (&params[0], binding);
g_value_init (&params[1], G_TYPE_VALUE);
g_value_set_boxed (&params[1], source);
g_value_init (&params[2], G_TYPE_VALUE);
g_value_set_boxed (&params[2], target);
g_value_init (&retval, G_TYPE_BOOLEAN);
g_value_set_boolean (&retval, FALSE);
g_closure_invoke (t_data->transform_to_closure, &retval, 3, params, NULL);
res = g_value_get_boolean (&retval);
if (res)
{
const GValue *out_value = g_value_get_boxed (&params[2]);
g_assert (out_value != NULL);
g_value_copy (out_value, target);
}
g_value_unset (&params[0]);
g_value_unset (&params[1]);
g_value_unset (&params[2]);
g_value_unset (&retval);
return res;
}
static gboolean
bind_with_closures_transform_from (GBinding *binding,
const GValue *source,
GValue *target,
gpointer data)
{
TransformData *t_data = data;
GValue params[3] = { G_VALUE_INIT, G_VALUE_INIT, G_VALUE_INIT };
GValue retval = G_VALUE_INIT;
gboolean res;
g_value_init (&params[0], G_TYPE_BINDING);
g_value_set_object (&params[0], binding);
g_value_init (&params[1], G_TYPE_VALUE);
g_value_set_boxed (&params[1], source);
g_value_init (&params[2], G_TYPE_VALUE);
g_value_set_boxed (&params[2], target);
g_value_init (&retval, G_TYPE_BOOLEAN);
g_value_set_boolean (&retval, FALSE);
g_closure_invoke (t_data->transform_from_closure, &retval, 3, params, NULL);
res = g_value_get_boolean (&retval);
if (res)
{
const GValue *out_value = g_value_get_boxed (&params[2]);
g_assert (out_value != NULL);
g_value_copy (out_value, target);
}
g_value_unset (&params[0]);
g_value_unset (&params[1]);
g_value_unset (&params[2]);
g_value_unset (&retval);
return res;
}
static void
bind_with_closures_free_func (gpointer data)
{
TransformData *t_data = data;
if (t_data->transform_to_closure != NULL)
g_closure_unref (t_data->transform_to_closure);
if (t_data->transform_from_closure != NULL)
g_closure_unref (t_data->transform_from_closure);
g_slice_free (TransformData, t_data);
}
/**
* g_object_bind_property_with_closures: (rename-to g_object_bind_property_full)
* @source: (type GObject.Object): the source #GObject
* @source_property: the property on @source to bind
* @target: (type GObject.Object): the target #GObject
* @target_property: the property on @target to bind
* @flags: flags to pass to #GBinding
* @transform_to: a #GClosure wrapping the transformation function
* from the @source to the @target, or %NULL to use the default
* @transform_from: a #GClosure wrapping the transformation function
* from the @target to the @source, or %NULL to use the default
*
* Creates a binding between @source_property on @source and @target_property
* on @target, allowing you to set the transformation functions to be used by
* the binding.
*
* This function is the language bindings friendly version of
* g_object_bind_property_full(), using #GClosures instead of
* function pointers.
*
* Returns: (transfer none): the #GBinding instance representing the
* binding between the two #GObject instances. The binding is released
* whenever the #GBinding reference count reaches zero.
*
* Since: 2.26
*/
GBinding *
g_object_bind_property_with_closures (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags,
GClosure *transform_to,
GClosure *transform_from)
{
TransformData *data;
data = g_slice_new0 (TransformData);
if (transform_to != NULL)
{
if (G_CLOSURE_NEEDS_MARSHAL (transform_to))
g_closure_set_marshal (transform_to, g_cclosure_marshal_BOOLEAN__BOXED_BOXED);
data->transform_to_closure = g_closure_ref (transform_to);
g_closure_sink (data->transform_to_closure);
}
if (transform_from != NULL)
{
if (G_CLOSURE_NEEDS_MARSHAL (transform_from))
g_closure_set_marshal (transform_from, g_cclosure_marshal_BOOLEAN__BOXED_BOXED);
data->transform_from_closure = g_closure_ref (transform_from);
g_closure_sink (data->transform_from_closure);
}
return g_object_bind_property_full (source, source_property,
target, target_property,
flags,
transform_to != NULL ? bind_with_closures_transform_to : NULL,
transform_from != NULL ? bind_with_closures_transform_from : NULL,
data,
bind_with_closures_free_func);
}
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