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gtk2/gtk/gtkconstraintlayout.c
Emmanuele Bassi cdf80f1d65 Add GtkConstraintLayout 
A layout manager using GtkConstraintSolver to measure and allocate
children.
2019-06-30 23:42:44 +01:00

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/* gtkconstraintlayout.c: Layout manager using constraints
* 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
*/
/**
* SECTION: gtkconstraintlayout
* @Title: GtkConstraintLayout
* @Short_description: A layout manager using constraints
*
* GtkConstraintLayout is a layout manager that uses relations between
* widget attributes, expressed via #GtkConstraint instances, to measure
* and allocate widgets.
*
* # How do constraints work
*
* Constraints are objects defining the relationship between attributes
* of a widget; you can read the description of the #GtkConstraint
* class to have a more in depth definition.
*
* By taking multiple constraints and applying them to the children of
* a widget using #GtkConstraintLayout, it's possible to describe complex
* layout policies; each constraint applied to a child or to the parent
* widgets contributes to the full description of the layout, in terms of
* parameters for resolving the value of each attribute.
*
* It is important to note that a layout is defined by the totality of
* constraints; removing a child, or a constraint, from an existing layout
* without changing the remaining constraints may result in an unstable
* or unsolvable layout.
*
* Constraints have an implicit "reading order"; you should start describing
* each edge of each child, as well as their relationship with the parent
* container, from the top left (or top right, in RTL languages), horizontally
* first, and then vertically.
*
* A constraint-based layout with too few constraints can become "unstable",
* that is: have more than one solution. The behavior of an unstable layout
* is undefined.
*
* A constraint-based layout with conflicting constraints may be unsolvable,
* and lead to an unstable layout.
*
*/
#include "config.h"
#include "gtkconstraintlayout.h"
#include "gtkconstraintprivate.h"
#include "gtkconstraintexpressionprivate.h"
#include "gtkconstraintsolverprivate.h"
#include "gtklayoutchild.h"
#include "gtkdebug.h"
#include "gtkintl.h"
#include "gtkprivate.h"
#include "gtksizerequest.h"
#include "gtkwidgetprivate.h"
struct _GtkConstraintLayoutChild
{
GtkLayoutChild parent_instance;
/* HashTable<static string, Variable>; a hash table of variables,
* one for each attribute; we use these to query and suggest the
* values for the solver. The string is static and does not need
* to be freed.
*/
GHashTable *bound_attributes;
/* Internal constraints on minimum and natural sizes */
GtkConstraintRef *width_constraint[2];
GtkConstraintRef *height_constraint[2];
};
struct _GtkConstraintLayout
{
GtkLayoutManager parent_instance;
/* A pointer to the GtkConstraintSolver used by the layout manager;
* we acquire one when the layout manager gets rooted, and release
* it when it gets unrooted.
*/
GtkConstraintSolver *solver;
/* HashTable<static string, Variable>; a hash table of variables,
* one for each attribute; we use these to query and suggest the
* values for the solver. The string is static and does not need
* to be freed.
*/
GHashTable *bound_attributes;
/* HashSet<GtkConstraint>; the set of constraints on the
* parent widget, using the public API objects.
*/
GHashTable *constraints;
};
G_DEFINE_TYPE (GtkConstraintLayoutChild, gtk_constraint_layout_child, GTK_TYPE_LAYOUT_CHILD)
static inline GtkConstraintSolver *
gtk_constraint_layout_get_solver (GtkConstraintLayout *self)
{
GtkWidget *widget;
GtkRoot *root;
if (self->solver != NULL)
return self->solver;
widget = gtk_layout_manager_get_widget (GTK_LAYOUT_MANAGER (self));
if (widget == NULL)
return NULL;
root = gtk_widget_get_root (widget);
if (root == NULL)
return NULL;
self->solver = gtk_root_get_constraint_solver (root);
return self->solver;
}
static const char * const attribute_names[] = {
[GTK_CONSTRAINT_ATTRIBUTE_NONE] = "none",
[GTK_CONSTRAINT_ATTRIBUTE_LEFT] = "left",
[GTK_CONSTRAINT_ATTRIBUTE_RIGHT] = "right",
[GTK_CONSTRAINT_ATTRIBUTE_TOP] = "top",
[GTK_CONSTRAINT_ATTRIBUTE_BOTTOM] = "bottom",
[GTK_CONSTRAINT_ATTRIBUTE_START] = "start",
[GTK_CONSTRAINT_ATTRIBUTE_END] = "end",
[GTK_CONSTRAINT_ATTRIBUTE_WIDTH] = "width",
[GTK_CONSTRAINT_ATTRIBUTE_HEIGHT] = "height",
[GTK_CONSTRAINT_ATTRIBUTE_CENTER_X] = "center-x",
[GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y] = "center-y",
[GTK_CONSTRAINT_ATTRIBUTE_BASELINE] = "baseline",
};
G_GNUC_PURE
static const char *
get_attribute_name (GtkConstraintAttribute attr)
{
return attribute_names[attr];
}
static GtkConstraintVariable *
get_child_attribute (GtkConstraintLayoutChild *self,
GtkConstraintSolver *solver,
GtkWidget *widget,
GtkConstraintAttribute attr)
{
GtkTextDirection text_dir;
const char *attr_name;
GtkConstraintVariable *res;
g_assert (attr != GTK_CONSTRAINT_ATTRIBUTE_NONE);
/* Resolve the start/end attributes depending on the layout's text direction */
if (attr == GTK_CONSTRAINT_ATTRIBUTE_START)
{
text_dir = gtk_widget_get_direction (widget);
if (text_dir == GTK_TEXT_DIR_RTL)
attr = GTK_CONSTRAINT_ATTRIBUTE_RIGHT;
else
attr = GTK_CONSTRAINT_ATTRIBUTE_LEFT;
}
else if (attr == GTK_CONSTRAINT_ATTRIBUTE_END)
{
text_dir = gtk_widget_get_direction (widget);
if (text_dir == GTK_TEXT_DIR_RTL)
attr = GTK_CONSTRAINT_ATTRIBUTE_LEFT;
else
attr = GTK_CONSTRAINT_ATTRIBUTE_RIGHT;
}
attr_name = get_attribute_name (attr);
res = g_hash_table_lookup (self->bound_attributes, attr_name);
if (res != NULL)
return res;
res = gtk_constraint_solver_create_variable (solver,
gtk_widget_get_name (widget),
attr_name,
0.0);
g_hash_table_insert (self->bound_attributes, (gpointer) attr_name, res);
/* Some attributes are really constraints computed from other
* attributes, to avoid creating additional constraints from
* the user's perspective
*/
switch (attr)
{
/* right = left + width */
case GTK_CONSTRAINT_ATTRIBUTE_RIGHT:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *left, *width;
GtkConstraintExpression *expr;
left = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
width = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
gtk_constraint_expression_builder_init (&builder, solver);
gtk_constraint_expression_builder_term (&builder, left);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, width);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_MEDIUM);
}
break;
/* bottom = top + height */
case GTK_CONSTRAINT_ATTRIBUTE_BOTTOM:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_TOP);
height = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
gtk_constraint_expression_builder_init (&builder, solver);
gtk_constraint_expression_builder_term (&builder, top);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, height);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_MEDIUM);
}
break;
/* centerX = (width / 2.0) + left*/
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_X:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *left, *width;
GtkConstraintExpression *expr;
left = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
width = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
gtk_constraint_expression_builder_init (&builder, solver);
gtk_constraint_expression_builder_term (&builder, width);
gtk_constraint_expression_builder_divide_by (&builder);
gtk_constraint_expression_builder_constant (&builder, 2.0);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, left);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* centerY = (height / 2.0) + top */
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_TOP);
height = get_child_attribute (self, solver, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
gtk_constraint_expression_builder_init (&builder, solver);
gtk_constraint_expression_builder_term (&builder, height);
gtk_constraint_expression_builder_divide_by (&builder);
gtk_constraint_expression_builder_constant (&builder, 2.0);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, top);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* We do not allow negative sizes */
case GTK_CONSTRAINT_ATTRIBUTE_WIDTH:
case GTK_CONSTRAINT_ATTRIBUTE_HEIGHT:
{
GtkConstraintExpression *expr;
expr = gtk_constraint_expression_new (0.0);
gtk_constraint_solver_add_constraint (solver,
res, GTK_CONSTRAINT_RELATION_GE, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* These are "pure" attributes */
case GTK_CONSTRAINT_ATTRIBUTE_NONE:
case GTK_CONSTRAINT_ATTRIBUTE_LEFT:
case GTK_CONSTRAINT_ATTRIBUTE_TOP:
case GTK_CONSTRAINT_ATTRIBUTE_BASELINE:
break;
/* These attributes must have been resolved to their real names */
case GTK_CONSTRAINT_ATTRIBUTE_START:
case GTK_CONSTRAINT_ATTRIBUTE_END:
g_assert_not_reached ();
break;
default:
break;
}
return res;
}
static void
gtk_constraint_layout_child_finalize (GObject *gobject)
{
GtkConstraintLayoutChild *self = GTK_CONSTRAINT_LAYOUT_CHILD (gobject);
GtkLayoutManager *manager;
GtkConstraintSolver *solver;
manager = gtk_layout_child_get_layout_manager (GTK_LAYOUT_CHILD (self));
solver = gtk_constraint_layout_get_solver (GTK_CONSTRAINT_LAYOUT (manager));
if (solver != NULL)
{
if (self->width_constraint[0] != NULL)
gtk_constraint_solver_remove_constraint (solver, self->width_constraint[0]);
if (self->width_constraint[1] != NULL)
gtk_constraint_solver_remove_constraint (solver, self->width_constraint[1]);
if (self->height_constraint[0] != NULL)
gtk_constraint_solver_remove_constraint (solver, self->height_constraint[0]);
if (self->height_constraint[1] != NULL)
gtk_constraint_solver_remove_constraint (solver, self->height_constraint[1]);
}
g_clear_pointer (&self->bound_attributes, g_hash_table_unref);
G_OBJECT_CLASS (gtk_constraint_layout_child_parent_class)->finalize (gobject);
}
static void
gtk_constraint_layout_child_class_init (GtkConstraintLayoutChildClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->finalize = gtk_constraint_layout_child_finalize;
}
static void
gtk_constraint_layout_child_init (GtkConstraintLayoutChild *self)
{
self->bound_attributes =
g_hash_table_new_full (g_str_hash, g_str_equal,
NULL,
(GDestroyNotify) gtk_constraint_variable_unref);
}
G_DEFINE_TYPE (GtkConstraintLayout, gtk_constraint_layout, GTK_TYPE_LAYOUT_MANAGER)
static void
gtk_constraint_layout_finalize (GObject *gobject)
{
GtkConstraintLayout *self = GTK_CONSTRAINT_LAYOUT (gobject);
g_clear_pointer (&self->bound_attributes, g_hash_table_unref);
g_clear_pointer (&self->constraints, g_hash_table_unref);
G_OBJECT_CLASS (gtk_constraint_layout_parent_class)->finalize (gobject);
}
static GtkConstraintVariable *
get_layout_attribute (GtkConstraintLayout *self,
GtkWidget *widget,
GtkConstraintAttribute attr)
{
GtkTextDirection text_dir;
const char *attr_name;
GtkConstraintVariable *res;
/* Resolve the start/end attributes depending on the layout's text direction */
if (attr == GTK_CONSTRAINT_ATTRIBUTE_START)
{
text_dir = gtk_widget_get_direction (widget);
if (text_dir == GTK_TEXT_DIR_RTL)
attr = GTK_CONSTRAINT_ATTRIBUTE_RIGHT;
else
attr = GTK_CONSTRAINT_ATTRIBUTE_LEFT;
}
else if (attr == GTK_CONSTRAINT_ATTRIBUTE_END)
{
text_dir = gtk_widget_get_direction (widget);
if (text_dir == GTK_TEXT_DIR_RTL)
attr = GTK_CONSTRAINT_ATTRIBUTE_LEFT;
else
attr = GTK_CONSTRAINT_ATTRIBUTE_RIGHT;
}
attr_name = get_attribute_name (attr);
res = g_hash_table_lookup (self->bound_attributes, attr_name);
if (res != NULL)
return res;
res = gtk_constraint_solver_create_variable (self->solver, "super", attr_name, 0.0);
g_hash_table_insert (self->bound_attributes, (gpointer) attr_name, res);
/* Some attributes are really constraints computed from other
* attributes, to avoid creating additional constraints from
* the user's perspective
*/
switch (attr)
{
/* right = left + width */
case GTK_CONSTRAINT_ATTRIBUTE_RIGHT:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *left, *width;
GtkConstraintExpression *expr;
left = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
width = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
gtk_constraint_expression_builder_init (&builder, self->solver);
gtk_constraint_expression_builder_term (&builder, left);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, width);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (self->solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* bottom = top + height */
case GTK_CONSTRAINT_ATTRIBUTE_BOTTOM:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_TOP);
height = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
gtk_constraint_expression_builder_init (&builder, self->solver);
gtk_constraint_expression_builder_term (&builder, top);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, height);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (self->solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* centerX = left + (width / 2.0) */
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_X:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *left, *width;
GtkConstraintExpression *expr;
left = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
width = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
gtk_constraint_expression_builder_init (&builder, self->solver);
gtk_constraint_expression_builder_term (&builder, width);
gtk_constraint_expression_builder_divide_by (&builder);
gtk_constraint_expression_builder_constant (&builder, 2.0);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, left);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (self->solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* centerY = top + (height / 2.0) */
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_TOP);
height = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
gtk_constraint_expression_builder_init (&builder, self->solver);
gtk_constraint_expression_builder_term (&builder, height);
gtk_constraint_expression_builder_divide_by (&builder);
gtk_constraint_expression_builder_constant (&builder, 2.0);
gtk_constraint_expression_builder_plus (&builder);
gtk_constraint_expression_builder_term (&builder, top);
expr = gtk_constraint_expression_builder_finish (&builder);
gtk_constraint_solver_add_constraint (self->solver,
res, GTK_CONSTRAINT_RELATION_EQ, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* We do not allow negative sizes */
case GTK_CONSTRAINT_ATTRIBUTE_WIDTH:
case GTK_CONSTRAINT_ATTRIBUTE_HEIGHT:
{
GtkConstraintExpression *expr;
expr = gtk_constraint_expression_new (0.0);
gtk_constraint_solver_add_constraint (self->solver,
res, GTK_CONSTRAINT_RELATION_GE, expr,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
}
break;
/* These are "pure" attributes */
case GTK_CONSTRAINT_ATTRIBUTE_NONE:
case GTK_CONSTRAINT_ATTRIBUTE_LEFT:
case GTK_CONSTRAINT_ATTRIBUTE_TOP:
case GTK_CONSTRAINT_ATTRIBUTE_BASELINE:
break;
/* These attributes must have been resolved to their real names */
case GTK_CONSTRAINT_ATTRIBUTE_START:
case GTK_CONSTRAINT_ATTRIBUTE_END:
g_assert_not_reached ();
break;
default:
break;
}
return res;
}
/*< private >
* layout_add_constraint:
* @self: a #GtkConstraintLayout
* @constraint: a #GtkConstraint
*
* Turns a #GtkConstraint into a #GtkConstraintRef inside the
* constraint solver associated to @self.
*
* If @self does not have a #GtkConstraintSolver, because it
* has not been rooted yet, we just store the @constraint instance,
* and we're going to call this function when the layout manager
* gets rooted.
*/
static void
layout_add_constraint (GtkConstraintLayout *self,
GtkConstraint *constraint)
{
GtkConstraintVariable *target_attr, *source_attr;
GtkConstraintExpressionBuilder builder;
GtkConstraintExpression *expr;
GtkConstraintSolver *solver;
GtkConstraintAttribute attr;
GtkWidget *target_widget, *source_widget;
GtkWidget *layout_widget;
if (gtk_constraint_is_attached (constraint))
return;
/* Once we pass the preconditions, we check if we can turn a GtkConstraint
* into a GtkConstraintRef; if we can't, we keep a reference to the
* constraint object and try later on
*/
layout_widget = gtk_layout_manager_get_widget (GTK_LAYOUT_MANAGER (self));
if (layout_widget == NULL)
return;
solver = gtk_constraint_layout_get_solver (self);
if (solver == NULL)
return;
attr = gtk_constraint_get_target_attribute (constraint);
target_widget = gtk_constraint_get_target_widget (constraint);
if (target_widget == NULL || target_widget == layout_widget)
{
/* A NULL target widget is assumed to be referring to the layout itself */
target_attr = get_layout_attribute (self, layout_widget, attr);
}
else if (gtk_widget_get_parent (target_widget) == layout_widget)
{
GtkLayoutChild *child_info;
child_info = gtk_layout_manager_get_layout_child (GTK_LAYOUT_MANAGER (self), target_widget);
target_attr = get_child_attribute (GTK_CONSTRAINT_LAYOUT_CHILD (child_info),
solver,
target_widget,
attr);
}
else
{
g_critical ("Unknown target widget '%s'", gtk_widget_get_name (target_widget));
target_attr = NULL;
}
if (target_attr == NULL)
return;
attr = gtk_constraint_get_source_attribute (constraint);
source_widget = gtk_constraint_get_source_widget (constraint);
/* The constraint is a constant */
if (attr == GTK_CONSTRAINT_ATTRIBUTE_NONE)
{
source_attr = NULL;
}
else
{
if (source_widget == NULL || source_widget == layout_widget)
{
source_attr = get_layout_attribute (self, layout_widget, attr);
}
else if (gtk_widget_get_parent (source_widget) == layout_widget)
{
GtkLayoutChild *child_info;
child_info = gtk_layout_manager_get_layout_child (GTK_LAYOUT_MANAGER (self), source_widget);
source_attr = get_child_attribute (GTK_CONSTRAINT_LAYOUT_CHILD (child_info),
solver,
source_widget,
attr);
}
else
{
g_critical ("Unknown source widget '%s'", gtk_widget_get_name (source_widget));
source_attr = NULL;
return;
}
}
/* Build the expression */
gtk_constraint_expression_builder_init (&builder, self->solver);
if (source_attr != NULL)
{
gtk_constraint_expression_builder_term (&builder, source_attr);
gtk_constraint_expression_builder_multiply_by (&builder);
gtk_constraint_expression_builder_constant (&builder, gtk_constraint_get_multiplier (constraint));
gtk_constraint_expression_builder_plus (&builder);
}
gtk_constraint_expression_builder_constant (&builder, gtk_constraint_get_constant (constraint));
expr = gtk_constraint_expression_builder_finish (&builder);
constraint->solver = solver;
constraint->constraint_ref =
gtk_constraint_solver_add_constraint (self->solver,
target_attr,
gtk_constraint_get_relation (constraint),
expr,
gtk_constraint_get_weight (constraint));
}
static void
gtk_constraint_layout_measure (GtkLayoutManager *manager,
GtkWidget *widget,
GtkOrientation orientation,
int for_size,
int *minimum,
int *natural,
int *minimum_baseline,
int *natural_baseline)
{
GtkConstraintLayout *self = GTK_CONSTRAINT_LAYOUT (manager);
GtkConstraintVariable *size, *opposite_size;
GtkConstraintSolver *solver;
GtkWidget *child;
int value;
solver = gtk_constraint_layout_get_solver (self);
if (solver == NULL)
return;
/* We measure each child in the layout and impose restrictions on the
* minimum and natural size, so we can solve the size of the overall
* layout later on
*/
for (child = _gtk_widget_get_first_child (widget);
child != NULL;
child = _gtk_widget_get_next_sibling (child))
{
GtkConstraintLayoutChild *child_info;
GtkConstraintVariable *width_var, *height_var;
int min_size = 0, nat_size = 0;
if (!gtk_widget_should_layout (child))
continue;
child_info = GTK_CONSTRAINT_LAYOUT_CHILD (gtk_layout_manager_get_layout_child (manager, child));
gtk_widget_measure (child, orientation, for_size,
&min_size, &nat_size,
NULL, NULL);
if (child_info->width_constraint[0] != NULL)
{
gtk_constraint_solver_remove_constraint (solver, child_info->width_constraint[0]);
gtk_constraint_solver_remove_constraint (solver, child_info->width_constraint[1]);
}
if (child_info->height_constraint[0] != NULL)
{
gtk_constraint_solver_remove_constraint (solver, child_info->height_constraint[0]);
gtk_constraint_solver_remove_constraint (solver, child_info->height_constraint[1]);
}
switch (orientation)
{
case GTK_ORIENTATION_HORIZONTAL:
width_var = get_child_attribute (child_info, solver, child,
GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
child_info->width_constraint[0] =
gtk_constraint_solver_add_constraint (solver,
width_var,
GTK_CONSTRAINT_RELATION_GE,
gtk_constraint_expression_new (min_size),
GTK_CONSTRAINT_WEIGHT_REQUIRED);
child_info->width_constraint[1] =
gtk_constraint_solver_add_constraint (solver,
width_var,
GTK_CONSTRAINT_RELATION_EQ,
gtk_constraint_expression_new (nat_size),
GTK_CONSTRAINT_WEIGHT_MEDIUM);
break;
case GTK_ORIENTATION_VERTICAL:
height_var = get_child_attribute (child_info, solver, child,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
child_info->height_constraint[0] =
gtk_constraint_solver_add_constraint (solver,
height_var,
GTK_CONSTRAINT_RELATION_GE,
gtk_constraint_expression_new (min_size),
GTK_CONSTRAINT_WEIGHT_REQUIRED);
child_info->height_constraint[1] =
gtk_constraint_solver_add_constraint (solver,
height_var,
GTK_CONSTRAINT_RELATION_EQ,
gtk_constraint_expression_new (nat_size),
GTK_CONSTRAINT_WEIGHT_MEDIUM);
break;
default:
break;
}
}
switch (orientation)
{
case GTK_ORIENTATION_HORIZONTAL:
size = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
opposite_size = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
break;
case GTK_ORIENTATION_VERTICAL:
size = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
opposite_size = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
break;
default:
g_assert_not_reached ();
}
g_assert (size != NULL && opposite_size != NULL);
/* We impose a temporary value on the size and opposite size of the
* layout, with a low weight to let the solver settle towards the
* natural state of the system. Once we get the value out, we can
* remove these constraints
*/
gtk_constraint_solver_add_edit_variable (solver, size, GTK_CONSTRAINT_WEIGHT_WEAK + 1);
gtk_constraint_solver_add_edit_variable (solver, opposite_size, GTK_CONSTRAINT_WEIGHT_WEAK + 2);
gtk_constraint_solver_begin_edit (solver);
gtk_constraint_solver_suggest_value (solver, size, 0.0);
gtk_constraint_solver_suggest_value (solver, opposite_size, for_size >= 0 ? for_size : 0.0);
gtk_constraint_solver_resolve (solver);
GTK_NOTE (LAYOUT,
g_print ("layout %p preferred %s size: %.3f (for opposite size: %d)\n",
self,
orientation == GTK_ORIENTATION_HORIZONTAL ? "horizontal" : "vertical",
gtk_constraint_variable_get_value (size),
for_size));
value = gtk_constraint_variable_get_value (size);
gtk_constraint_solver_remove_edit_variable (solver, size);
gtk_constraint_solver_remove_edit_variable (solver, opposite_size);
gtk_constraint_solver_end_edit (solver);
if (minimum != NULL)
*minimum = value;
if (natural != NULL)
*natural = value;
}
static void
gtk_constraint_layout_allocate (GtkLayoutManager *manager,
GtkWidget *widget,
int width,
int height,
int baseline)
{
GtkConstraintLayout *self = GTK_CONSTRAINT_LAYOUT (manager);
GtkConstraintRef *stay_w, *stay_h, *stay_t, *stay_l;
GtkConstraintSolver *solver;
GtkConstraintVariable *layout_top, *layout_height;
GtkConstraintVariable *layout_left, *layout_width;
GtkWidget *child;
solver = gtk_constraint_layout_get_solver (self);
if (solver == NULL)
return;
/* We add required stay constraints to ensure that the layout remains
* within the bounds of the allocation
*/
layout_top = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_TOP);
layout_left = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
layout_width = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
layout_height = get_layout_attribute (self, widget, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
gtk_constraint_variable_set_value (layout_top, 0.0);
stay_t = gtk_constraint_solver_add_stay_variable (solver,
layout_top,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
gtk_constraint_variable_set_value (layout_left, 0.0);
stay_l = gtk_constraint_solver_add_stay_variable (solver,
layout_left,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
gtk_constraint_variable_set_value (layout_width, width);
stay_w = gtk_constraint_solver_add_stay_variable (solver,
layout_width,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
gtk_constraint_variable_set_value (layout_height, height);
stay_h = gtk_constraint_solver_add_stay_variable (solver,
layout_height,
GTK_CONSTRAINT_WEIGHT_REQUIRED);
GTK_NOTE (LAYOUT,
g_print ("Layout [%p]: { .x: %g, .y: %g, .w: %g, .h: %g }\n",
self,
gtk_constraint_variable_get_value (layout_left),
gtk_constraint_variable_get_value (layout_top),
gtk_constraint_variable_get_value (layout_width),
gtk_constraint_variable_get_value (layout_height)));
/* We reset the constraints on the size of each child, so we are sure the
* layout is up to date
*/
for (child = _gtk_widget_get_first_child (widget);
child != NULL;
child = _gtk_widget_get_next_sibling (child))
{
GtkConstraintLayoutChild *child_info;
GtkConstraintVariable *width_var, *height_var;
GtkRequisition min_req, nat_req;
if (!gtk_widget_should_layout (child))
continue;
child_info = GTK_CONSTRAINT_LAYOUT_CHILD (gtk_layout_manager_get_layout_child (manager, child));
gtk_widget_get_preferred_size (child, &min_req, &nat_req);
if (child_info->width_constraint[0] != NULL)
{
gtk_constraint_solver_remove_constraint (solver, child_info->width_constraint[0]);
gtk_constraint_solver_remove_constraint (solver, child_info->width_constraint[1]);
}
if (child_info->height_constraint[0] != NULL)
{
gtk_constraint_solver_remove_constraint (solver, child_info->height_constraint[0]);
gtk_constraint_solver_remove_constraint (solver, child_info->height_constraint[1]);
}
width_var = get_child_attribute (child_info, solver, child,
GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
child_info->width_constraint[0] =
gtk_constraint_solver_add_constraint (solver,
width_var,
GTK_CONSTRAINT_RELATION_GE,
gtk_constraint_expression_new (min_req.width),
GTK_CONSTRAINT_WEIGHT_REQUIRED);
child_info->width_constraint[1] =
gtk_constraint_solver_add_constraint (solver,
width_var,
GTK_CONSTRAINT_RELATION_EQ,
gtk_constraint_expression_new (nat_req.width),
GTK_CONSTRAINT_WEIGHT_MEDIUM);
height_var = get_child_attribute (child_info, solver, child,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
child_info->height_constraint[0] =
gtk_constraint_solver_add_constraint (solver,
height_var,
GTK_CONSTRAINT_RELATION_GE,
gtk_constraint_expression_new (min_req.height),
GTK_CONSTRAINT_WEIGHT_REQUIRED);
child_info->height_constraint[1] =
gtk_constraint_solver_add_constraint (solver,
height_var,
GTK_CONSTRAINT_RELATION_EQ,
gtk_constraint_expression_new (nat_req.height),
GTK_CONSTRAINT_WEIGHT_MEDIUM);
}
for (child = _gtk_widget_get_first_child (widget);
child != NULL;
child = _gtk_widget_get_next_sibling (child))
{
GtkConstraintVariable *var_top, *var_left, *var_width, *var_height;
GtkConstraintVariable *var_baseline;
GtkConstraintLayoutChild *child_info;
GtkAllocation child_alloc;
int child_baseline = -1;
if (!gtk_widget_should_layout (child))
continue;
child_info = GTK_CONSTRAINT_LAYOUT_CHILD (gtk_layout_manager_get_layout_child (manager, child));
/* Retrieve all the values associated with the child */
var_top = get_child_attribute (child_info, solver, child, GTK_CONSTRAINT_ATTRIBUTE_TOP);
var_left = get_child_attribute (child_info, solver, child, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
var_width = get_child_attribute (child_info, solver, child, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
var_height = get_child_attribute (child_info, solver, child, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
var_baseline = get_child_attribute (child_info, solver, child, GTK_CONSTRAINT_ATTRIBUTE_BASELINE);
GTK_NOTE (LAYOUT,
g_print ("Allocating child '%s'[%p] with { .x: %g, .y: %g, .w: %g, .h: %g, .b: %g }\n",
gtk_widget_get_name (child), child,
gtk_constraint_variable_get_value (var_left),
gtk_constraint_variable_get_value (var_top),
gtk_constraint_variable_get_value (var_width),
gtk_constraint_variable_get_value (var_height),
gtk_constraint_variable_get_value (var_baseline)));
child_alloc.x = floor (gtk_constraint_variable_get_value (var_left));
child_alloc.y = floor (gtk_constraint_variable_get_value (var_top));
child_alloc.width = ceil (gtk_constraint_variable_get_value (var_width));
child_alloc.height = ceil (gtk_constraint_variable_get_value (var_height));
if (gtk_constraint_variable_get_value (var_baseline) > 0)
child_baseline = floor (gtk_constraint_variable_get_value (var_baseline));
gtk_widget_size_allocate (GTK_WIDGET (child),
&child_alloc,
child_baseline);
}
/* The allocation stay constraints are not needed any more */
gtk_constraint_solver_remove_constraint (solver, stay_w);
gtk_constraint_solver_remove_constraint (solver, stay_h);
gtk_constraint_solver_remove_constraint (solver, stay_t);
gtk_constraint_solver_remove_constraint (solver, stay_l);
}
static void
gtk_constraint_layout_root (GtkLayoutManager *manager)
{
GtkConstraintLayout *self = GTK_CONSTRAINT_LAYOUT (manager);
GHashTableIter iter;
GtkWidget *widget;
GtkRoot *root;
gpointer key;
widget = gtk_layout_manager_get_widget (manager);
root = gtk_widget_get_root (widget);
self->solver = gtk_root_get_constraint_solver (root);
/* Now that we have a solver, attach all constraints we have */
g_hash_table_iter_init (&iter, self->constraints);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraint *constraint = key;
layout_add_constraint (self, constraint);
}
}
static void
gtk_constraint_layout_unroot (GtkLayoutManager *manager)
{
GtkConstraintLayout *self = GTK_CONSTRAINT_LAYOUT (manager);
GHashTableIter iter;
gpointer key;
/* Detach all constraints we're holding, as we're removing the layout
* from the global solver, and they should not contribute to the other
* layouts
*/
g_hash_table_iter_init (&iter, self->constraints);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraint *constraint = key;
gtk_constraint_detach (constraint);
}
self->solver = NULL;
}
static void
gtk_constraint_layout_class_init (GtkConstraintLayoutClass *klass)
{
GtkLayoutManagerClass *manager_class = GTK_LAYOUT_MANAGER_CLASS (klass);
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->finalize = gtk_constraint_layout_finalize;
manager_class->layout_child_type = GTK_TYPE_CONSTRAINT_LAYOUT_CHILD;
manager_class->measure = gtk_constraint_layout_measure;
manager_class->allocate = gtk_constraint_layout_allocate;
manager_class->root = gtk_constraint_layout_root;
manager_class->unroot = gtk_constraint_layout_unroot;
}
static void
gtk_constraint_layout_init (GtkConstraintLayout *self)
{
/* The bound variables in the solver */
self->bound_attributes =
g_hash_table_new_full (g_str_hash, g_str_equal,
NULL,
(GDestroyNotify) gtk_constraint_variable_unref);
/* The GtkConstraint instances we own */
self->constraints =
g_hash_table_new_full (NULL, NULL,
(GDestroyNotify) g_object_unref,
NULL);
}
/**
* gtk_constraint_layout_new:
*
* Creates a new #GtkConstraintLayout layout manager.
*
* Returns: the newly created #GtkConstraintLayout
*/
GtkLayoutManager *
gtk_constraint_layout_new (void)
{
return g_object_new (GTK_TYPE_CONSTRAINT_LAYOUT, NULL);
}
/**
* gtk_constraint_layout_add_constraint:
* @manager: a #GtkConstraintLayout
* @constraint: (transfer full): a #GtkConstraint
*
* Adds a #GtkConstraint to the layout manager.
*
* The #GtkConstraint:source-widget and #GtkConstraint:target-widget
* properties of @constraint can be:
*
* - set to %NULL to indicate that the constraint refers to the
* widget using @manager
* - set to the #GtkWidget using @manager
* - set to a child of the #GtkWidget using @manager
*
* The @manager acquires the ownership of @constraint after calling
* this function.
*/
void
gtk_constraint_layout_add_constraint (GtkConstraintLayout *manager,
GtkConstraint *constraint)
{
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (manager));
g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
g_return_if_fail (!gtk_constraint_is_attached (constraint));
layout_add_constraint (manager, constraint);
g_hash_table_add (manager->constraints, constraint);
}
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