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Learning_GTK4_tree/gtk/gtkconstraint.c

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2023-12-12 11:36:42 +01:00
/* gtkconstraint.c: Constraint between two widgets
* Copyright 2019 GNOME Foundation
*
* 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
*/
/**
* GtkConstraint:
*
* `GtkConstraint` describes a constraint between attributes of two widgets,
* expressed as a linear equation.
*
* The typical equation for a constraint is:
*
* ```
* target.target_attr = source.source_attr × multiplier + constant
* ```
*
* Each `GtkConstraint` is part of a system that will be solved by a
* [class@Gtk.ConstraintLayout] in order to allocate and position each
* child widget or guide.
*
* The source and target, as well as their attributes, of a `GtkConstraint`
* instance are immutable after creation.
*/
#include "config.h"
#include "gtkconstraintprivate.h"
#include "gtkconstraintsolverprivate.h"
#include "gtktypebuiltins.h"
#include "gtkwidget.h"
enum {
PROP_TARGET = 1,
PROP_TARGET_ATTRIBUTE,
PROP_RELATION,
PROP_SOURCE,
PROP_SOURCE_ATTRIBUTE,
PROP_MULTIPLIER,
PROP_CONSTANT,
PROP_STRENGTH,
N_PROPERTIES
};
static GParamSpec *obj_props[N_PROPERTIES];
G_DEFINE_TYPE (GtkConstraint, gtk_constraint, G_TYPE_OBJECT)
static void
gtk_constraint_set_property (GObject *gobject,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GtkConstraint *self = GTK_CONSTRAINT (gobject);
switch (prop_id)
{
case PROP_TARGET:
self->target = g_value_get_object (value);
break;
case PROP_TARGET_ATTRIBUTE:
self->target_attribute = g_value_get_enum (value);
break;
case PROP_RELATION:
self->relation = g_value_get_enum (value);
break;
case PROP_SOURCE:
self->source = g_value_get_object (value);
break;
case PROP_SOURCE_ATTRIBUTE:
self->source_attribute = g_value_get_enum (value);
break;
case PROP_MULTIPLIER:
self->multiplier = g_value_get_double (value);
break;
case PROP_CONSTANT:
self->constant = g_value_get_double (value);
break;
case PROP_STRENGTH:
self->strength = g_value_get_int (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
static void
gtk_constraint_get_property (GObject *gobject,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GtkConstraint *self = GTK_CONSTRAINT (gobject);
switch (prop_id)
{
case PROP_TARGET:
g_value_set_object (value, self->target);
break;
case PROP_TARGET_ATTRIBUTE:
g_value_set_enum (value, self->target_attribute);
break;
case PROP_RELATION:
g_value_set_enum (value, self->relation);
break;
case PROP_SOURCE:
g_value_set_object (value, self->source);
break;
case PROP_SOURCE_ATTRIBUTE:
g_value_set_enum (value, self->source_attribute);
break;
case PROP_MULTIPLIER:
g_value_set_double (value, self->multiplier);
break;
case PROP_CONSTANT:
g_value_set_double (value, self->constant);
break;
case PROP_STRENGTH:
g_value_set_int (value, self->strength);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
static void
gtk_constraint_finalize (GObject *gobject)
{
GtkConstraint *self = GTK_CONSTRAINT (gobject);
gtk_constraint_detach (self);
G_OBJECT_CLASS (gtk_constraint_parent_class)->finalize (gobject);
}
static void
gtk_constraint_class_init (GtkConstraintClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->set_property = gtk_constraint_set_property;
gobject_class->get_property = gtk_constraint_get_property;
gobject_class->finalize = gtk_constraint_finalize;
/**
* GtkConstraint:target: (attributes org.gtk.Property.get=gtk_constraint_get_target)
*
* The target of the constraint.
*
* The constraint will set the [property@Gtk.Constraint:target-attribute]
* property of the target using the [property@Gtk.Constraint:source-attribute]
* property of the source widget.
*
*
*/
obj_props[PROP_TARGET] =
g_param_spec_object ("target", NULL, NULL,
GTK_TYPE_CONSTRAINT_TARGET,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:target-attribute: (attributes org.gtk.Property.get=gtk_constraint_get_target_attribute)
*
* The attribute of the [property@Gtk.Constraint:target] set by the constraint.
*/
obj_props[PROP_TARGET_ATTRIBUTE] =
g_param_spec_enum ("target-attribute", NULL, NULL,
GTK_TYPE_CONSTRAINT_ATTRIBUTE,
GTK_CONSTRAINT_ATTRIBUTE_NONE,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:relation: (attributes org.gtk.Property.get=gtk_constraint_get_relation)
*
* The order relation between the terms of the constraint.
*/
obj_props[PROP_RELATION] =
g_param_spec_enum ("relation", NULL, NULL,
GTK_TYPE_CONSTRAINT_RELATION,
GTK_CONSTRAINT_RELATION_EQ,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:source: (attributes org.gtk.Property.get=gtk_constraint_get_source)
*
* The source of the constraint.
*
* The constraint will set the [property@Gtk.Constraint:target-attribute]
* property of the target using the [property@Gtk.Constraint:source-attribute]
* property of the source.
*/
obj_props[PROP_SOURCE] =
g_param_spec_object ("source", NULL, NULL,
GTK_TYPE_CONSTRAINT_TARGET,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:source-attribute: (attributes org.gtk.Property.get=gtk_constraint_get_source_attribute)
*
* The attribute of the [property@Gtk.Constraint:source] read by the
* constraint.
*/
obj_props[PROP_SOURCE_ATTRIBUTE] =
g_param_spec_enum ("source-attribute", NULL, NULL,
GTK_TYPE_CONSTRAINT_ATTRIBUTE,
GTK_CONSTRAINT_ATTRIBUTE_NONE,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:multiplier: (attributes org.gtk.Property.get=gtk_constraint_get_multiplier)
*
* The multiplication factor to be applied to
* the [property@Gtk.Constraint:source-attribute].
*/
obj_props[PROP_MULTIPLIER] =
g_param_spec_double ("multiplier", NULL, NULL,
-G_MAXDOUBLE, G_MAXDOUBLE, 1.0,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:constant: (attributes org.gtk.Property.get=gtk_constraint_get_constant)
*
* The constant value to be added to the [property@Gtk.Constraint:source-attribute].
*/
obj_props[PROP_CONSTANT] =
g_param_spec_double ("constant", NULL, NULL,
-G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkConstraint:strength: (attributes org.gtk.Property.get=gtk_constraint_get_strength)
*
* The strength of the constraint.
*
* The strength can be expressed either using one of the symbolic values
* of the [enum@Gtk.ConstraintStrength] enumeration, or any positive integer
* value.
*/
obj_props[PROP_STRENGTH] =
g_param_spec_int ("strength", NULL, NULL,
0, GTK_CONSTRAINT_STRENGTH_REQUIRED,
GTK_CONSTRAINT_STRENGTH_REQUIRED,
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT_ONLY);
g_object_class_install_properties (gobject_class, N_PROPERTIES, obj_props);
}
static void
gtk_constraint_init (GtkConstraint *self)
{
self->multiplier = 1.0;
self->constant = 0.0;
self->target_attribute = GTK_CONSTRAINT_ATTRIBUTE_NONE;
self->source_attribute = GTK_CONSTRAINT_ATTRIBUTE_NONE;
self->relation = GTK_CONSTRAINT_RELATION_EQ;
self->strength = GTK_CONSTRAINT_STRENGTH_REQUIRED;
}
/**
* gtk_constraint_new: (constructor)
* @target: (nullable) (type GtkConstraintTarget): the target of the constraint
* @target_attribute: the attribute of `target` to be set
* @relation: the relation equivalence between `target_attribute` and `source_attribute`
* @source: (nullable) (type GtkConstraintTarget): the source of the constraint
* @source_attribute: the attribute of `source` to be read
* @multiplier: a multiplication factor to be applied to `source_attribute`
* @constant: a constant factor to be added to `source_attribute`
* @strength: the strength of the constraint
*
* Creates a new constraint representing a relation between a layout
* attribute on a source and a layout attribute on a target.
*
* Returns: (transfer full): the newly created constraint
*/
GtkConstraint *
gtk_constraint_new (gpointer target,
GtkConstraintAttribute target_attribute,
GtkConstraintRelation relation,
gpointer source,
GtkConstraintAttribute source_attribute,
double multiplier,
double constant,
int strength)
{
g_return_val_if_fail (target == NULL || GTK_IS_CONSTRAINT_TARGET (target), NULL);
g_return_val_if_fail (source == NULL || GTK_IS_CONSTRAINT_TARGET (source), NULL);
return g_object_new (GTK_TYPE_CONSTRAINT,
"target", target,
"target-attribute", target_attribute,
"relation", relation,
"source", source,
"source-attribute", source_attribute,
"multiplier", multiplier,
"constant", constant,
"strength", strength,
NULL);
}
/**
* gtk_constraint_new_constant: (constructor)
* @target: (nullable) (type GtkConstraintTarget): a the target of the constraint
* @target_attribute: the attribute of `target` to be set
* @relation: the relation equivalence between `target_attribute` and `constant`
* @constant: a constant factor to be set on `target_attribute`
* @strength: the strength of the constraint
*
* Creates a new constraint representing a relation between a layout
* attribute on a target and a constant value.
*
* Returns: (transfer full): the newly created constraint
*/
GtkConstraint *
gtk_constraint_new_constant (gpointer target,
GtkConstraintAttribute target_attribute,
GtkConstraintRelation relation,
double constant,
int strength)
{
g_return_val_if_fail (target == NULL || GTK_IS_CONSTRAINT_TARGET (target), NULL);
return g_object_new (GTK_TYPE_CONSTRAINT,
"target", target,
"target-attribute", target_attribute,
"relation", relation,
"source-attribute", GTK_CONSTRAINT_ATTRIBUTE_NONE,
"constant", constant,
"strength", strength,
NULL);
}
/**
* gtk_constraint_get_target: (attributes org.gtk.Method.get_property=target)
* @constraint: a `GtkConstraint`
*
* Retrieves the [iface@Gtk.ConstraintTarget] used as the target for
* the constraint.
*
* If the targe is set to `NULL` at creation, the constraint will use
* the widget using the [class@Gtk.ConstraintLayout] as the target.
*
* Returns: (transfer none) (nullable): a `GtkConstraintTarget`
*/
GtkConstraintTarget *
gtk_constraint_get_target (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), NULL);
return constraint->target;
}
/**
* gtk_constraint_get_target_attribute: (attributes org.gtk.Method.get_property=target-attribute)
* @constraint: a `GtkConstraint`
*
* Retrieves the attribute of the target to be set by the constraint.
*
* Returns: the target's attribute
*/
GtkConstraintAttribute
gtk_constraint_get_target_attribute (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_ATTRIBUTE_NONE);
return constraint->target_attribute;
}
/**
* gtk_constraint_get_source: (attributes org.gtk.Method.get_property=source)
* @constraint: a `GtkConstraint`
*
* Retrieves the [iface@Gtk.ConstraintTarget] used as the source for the
* constraint.
*
* If the source is set to `NULL` at creation, the constraint will use
* the widget using the [class@Gtk.ConstraintLayout] as the source.
*
* Returns: (transfer none) (nullable): the source of the constraint
*/
GtkConstraintTarget *
gtk_constraint_get_source (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), NULL);
return constraint->source;
}
/**
* gtk_constraint_get_source_attribute: (attributes org.gtk.Method.get_property=source-attribute)
* @constraint: a `GtkConstraint`
*
* Retrieves the attribute of the source to be read by the constraint.
*
* Returns: the source's attribute
*/
GtkConstraintAttribute
gtk_constraint_get_source_attribute (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_ATTRIBUTE_NONE);
return constraint->source_attribute;
}
/**
* gtk_constraint_get_relation: (attributes org.gtk.Method.get_property=relation)
* @constraint: a `GtkConstraint`
*
* The order relation between the terms of the constraint.
*
* Returns: a relation type
*/
GtkConstraintRelation
gtk_constraint_get_relation (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_RELATION_EQ);
return constraint->relation;
}
/**
* gtk_constraint_get_multiplier: (attributes org.gtk.Method.get_property=multiplier)
* @constraint: a `GtkConstraint`
*
* Retrieves the multiplication factor applied to the source
* attribute's value.
*
* Returns: a multiplication factor
*/
double
gtk_constraint_get_multiplier (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), 1.0);
return constraint->multiplier;
}
/**
* gtk_constraint_get_constant: (attributes org.gtk.Method.get_property=constant)
* @constraint: a `GtkConstraint`
*
* Retrieves the constant factor added to the source attributes' value.
*
* Returns: a constant factor
*/
double
gtk_constraint_get_constant (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), 0.0);
return constraint->constant;
}
/**
* gtk_constraint_get_strength: (attributes org.gtk.Method.get_property=strength)
* @constraint: a `GtkConstraint`
*
* Retrieves the strength of the constraint.
*
* Returns: the strength value
*/
int
gtk_constraint_get_strength (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_STRENGTH_REQUIRED);
return constraint->strength;
}
/**
* gtk_constraint_is_required:
* @constraint: a `GtkConstraint`
*
* Checks whether the constraint is a required relation for solving the
* constraint layout.
*
* Returns: %TRUE if the constraint is required
*/
gboolean
gtk_constraint_is_required (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
return constraint->strength == GTK_CONSTRAINT_STRENGTH_REQUIRED;
}
/**
* gtk_constraint_is_attached:
* @constraint: a `GtkConstraint`
*
* Checks whether the constraint is attached to a [class@Gtk.ConstraintLayout],
* and it is contributing to the layout.
*
* Returns: `TRUE` if the constraint is attached
*/
gboolean
gtk_constraint_is_attached (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
return constraint->constraint_ref != NULL;
}
/**
* gtk_constraint_is_constant:
* @constraint: a `GtkConstraint`
*
* Checks whether the constraint describes a relation between an attribute
* on the [property@Gtk.Constraint:target] and a constant value.
*
* Returns: `TRUE` if the constraint is a constant relation
*/
gboolean
gtk_constraint_is_constant (GtkConstraint *constraint)
{
g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
return constraint->source == NULL &&
constraint->source_attribute == GTK_CONSTRAINT_ATTRIBUTE_NONE;
}
void
gtk_constraint_attach (GtkConstraint *constraint,
GtkConstraintSolver *solver,
GtkConstraintRef *ref)
{
g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
g_return_if_fail (GTK_IS_CONSTRAINT_SOLVER (solver));
g_return_if_fail (ref != NULL);
constraint->constraint_ref = ref;
constraint->solver = solver;
}
void
gtk_constraint_detach (GtkConstraint *constraint)
{
g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
if (constraint->constraint_ref == NULL)
return;
gtk_constraint_solver_remove_constraint (constraint->solver, constraint->constraint_ref);
constraint->constraint_ref = NULL;
constraint->solver = NULL;
}
typedef struct _GtkConstraintTargetInterface GtkConstraintTargetInterface;
struct _GtkConstraintTargetInterface
{
GTypeInterface g_iface;
};
G_DEFINE_INTERFACE (GtkConstraintTarget, gtk_constraint_target, G_TYPE_OBJECT)
static void
gtk_constraint_target_default_init (GtkConstraintTargetInterface *iface)
{
}