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gtk2/gtk/gtkconstraintlayout.c
Matthias Clasen a39bbb2041 constraints: Make internal consistency required 
The relations between left, right, width
and top, bottom, height are required for
internal consistency. It doesn't make sense
to ever drop these.

Changing the strength of these relations makes
my systems behave much more stable.
2019-06-30 23:42:44 +01:00

1129 lines
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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_REQUIRED);
}
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_REQUIRED);
}
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);
}
/**
* gtk_constraint_layout_remove_constraint:
* @manager: a #GtkConstraintLayout
* @constraint: a #GtkConstraint
*
* Removes @constraint from the layout manager,
* so that it no longer influences the layout.
*/
void
gtk_constraint_layout_remove_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));
gtk_constraint_detach (constraint);
g_hash_table_remove (manager->constraints, constraint);
}
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