luc14n0/glib
1
0
Fork 0
mirror of https://gitlab.gnome.org/GNOME/glib.git synced 2024-11-06 01:16:17 +01:00
Code Issues Packages Projects Releases Wiki Activity
f92d179f77
glib/gobject/gbinding.c
Daniel Boles 54b04f74bd Binding: bind_property’s @notify func is nullable 
This is for destroying resources needed by transformations. But the user
may not need any such resources. Make it obvious that, instead of having
to point to a no-op function, @notify is checked and not called if NULL.

https://bugzilla.gnome.org/show_bug.cgi?id=792098
2018-01-01 17:23:16 +00:00

1186 lines
38 KiB
C
Raw Blame History

/* 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 2.1 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) (nullable): the transformation function
* from the @source to the @target, or %NULL to use the default
* @transform_from: (scope notified) (nullable): 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: (nullable): a function to call when disposing the binding, to free
* resources used by the transformation functions, or %NULL if not required
*
* 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);
}
Reference in New Issue View Git Blame Copy Permalink