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gtk2/gtk/gtkconstraintlayout.c
Emmanuele Bassi 4dd1de4129 Use explicit values for constraint strength 
Instead of playing games with mapping negative symbolic values to
positive ones, let's use the appropriate constants everywhere. This
allows us to use:

        GTK_CONSTRAINT_STRENGTH_WEAK * 2

Or

        GTK_CONSTRAINT_STRENGTH_STRONG + 1

In code using the public API.

We also store the strength values as integers, so we can compare them
properly, and only turn them into doubles when they are inserted into
the solver, just like every other variable.
2019-07-01 12:39:24 +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 "gtkconstraintlayoutprivate.h"
#include "gtkconstraintprivate.h"
#include "gtkconstraintexpressionprivate.h"
#include "gtkconstraintguideprivate.h"
#include "gtkconstraintsolverprivate.h"
#include "gtkconstraintvflparserprivate.h"
#include "gtkdebug.h"
#include "gtklayoutchild.h"
#include "gtkintl.h"
#include "gtkprivate.h"
#include "gtksizerequest.h"
#include "gtkwidgetprivate.h"
enum {
MIN_WIDTH,
MIN_HEIGHT,
NAT_WIDTH,
NAT_HEIGHT,
LAST_VALUE
};
struct _GtkConstraintLayoutChild
{
GtkLayoutChild parent_instance;
int values[LAST_VALUE];
GtkConstraintRef *constraints[LAST_VALUE];
/* 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;
};
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;
/* HashSet<GtkConstraintGuide> */
GHashTable *guides;
};
G_DEFINE_TYPE (GtkConstraintLayoutChild, gtk_constraint_layout_child, GTK_TYPE_LAYOUT_CHILD)
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 GtkConstraintAttribute
resolve_direction (GtkConstraintAttribute attr,
GtkWidget *widget)
{
GtkTextDirection text_dir;
/* Resolve the start/end attributes depending on the layout's text direction */
if (widget)
text_dir = gtk_widget_get_direction (widget);
else
text_dir = GTK_TEXT_DIR_LTR;
if (attr == GTK_CONSTRAINT_ATTRIBUTE_START)
{
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)
{
if (text_dir == GTK_TEXT_DIR_RTL)
attr = GTK_CONSTRAINT_ATTRIBUTE_LEFT;
else
attr = GTK_CONSTRAINT_ATTRIBUTE_RIGHT;
}
return attr;
}
GtkConstraintVariable *
gtk_constraint_layout_get_attribute (GtkConstraintLayout *layout,
GtkConstraintAttribute attr,
const char *prefix,
GtkWidget *widget,
GHashTable *bound_attributes)
{
const char *attr_name;
GtkConstraintVariable *res;
GtkConstraintSolver *solver = layout->solver;
attr = resolve_direction (attr, widget);
attr_name = get_attribute_name (attr);
res = g_hash_table_lookup (bound_attributes, attr_name);
if (res != NULL)
return res;
res = gtk_constraint_solver_create_variable (solver, prefix, attr_name, 0.0);
g_hash_table_insert (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 = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_LEFT, prefix, widget, bound_attributes);
width = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_WIDTH, prefix, widget, bound_attributes);
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_STRENGTH_REQUIRED);
}
break;
/* bottom = top + height */
case GTK_CONSTRAINT_ATTRIBUTE_BOTTOM:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_TOP, prefix, widget, bound_attributes);
height = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT, prefix, widget, bound_attributes);
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_STRENGTH_REQUIRED);
}
break;
/* centerX = (width / 2.0) + left*/
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_X:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *left, *width;
GtkConstraintExpression *expr;
left = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_LEFT, prefix, widget, bound_attributes);
width = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_WIDTH, prefix, widget, bound_attributes);
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_STRENGTH_REQUIRED);
}
break;
/* centerY = (height / 2.0) + top */
case GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y:
{
GtkConstraintExpressionBuilder builder;
GtkConstraintVariable *top, *height;
GtkConstraintExpression *expr;
top = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_TOP, prefix, widget, bound_attributes);
height = gtk_constraint_layout_get_attribute (layout, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT, prefix, widget, bound_attributes);
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_STRENGTH_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_STRENGTH_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 GtkConstraintVariable *
get_child_attribute (GtkConstraintLayout *layout,
GtkWidget *widget,
GtkConstraintAttribute attr)
{
GtkConstraintLayoutChild *child_info;
const char *prefix = gtk_widget_get_name (widget);
child_info = GTK_CONSTRAINT_LAYOUT_CHILD (gtk_layout_manager_get_layout_child (GTK_LAYOUT_MANAGER (layout), widget));
return gtk_constraint_layout_get_attribute (layout, attr, prefix, widget, child_info->bound_attributes);
}
static void
gtk_constraint_layout_child_finalize (GObject *gobject)
{
GtkConstraintLayoutChild *self = GTK_CONSTRAINT_LAYOUT_CHILD (gobject);
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_clear_pointer (&self->guides, 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_STRENGTH_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_STRENGTH_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_STRENGTH_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_STRENGTH_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_STRENGTH_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;
GtkConstraintTarget *target, *source;
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 = gtk_constraint_get_target (constraint);
if (target == NULL || target == GTK_CONSTRAINT_TARGET (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_IS_WIDGET (target) &&
gtk_widget_get_parent (GTK_WIDGET (target)) == layout_widget)
{
target_attr = get_child_attribute (self, GTK_WIDGET (target), attr);
}
else if (GTK_IS_CONSTRAINT_GUIDE (target))
{
GtkConstraintGuide *guide;
guide = (GtkConstraintGuide*)g_hash_table_lookup (self->guides, target);
target_attr = gtk_constraint_guide_get_attribute (guide, attr);
}
else
{
g_critical ("Unknown target widget '%p'", target);
target_attr = NULL;
}
if (target_attr == NULL)
return;
attr = gtk_constraint_get_source_attribute (constraint);
source = gtk_constraint_get_source (constraint);
/* The constraint is a constant */
if (attr == GTK_CONSTRAINT_ATTRIBUTE_NONE)
{
source_attr = NULL;
}
else
{
if (source == NULL || source == GTK_CONSTRAINT_TARGET (layout_widget))
{
source_attr = get_layout_attribute (self, layout_widget, attr);
}
else if (GTK_IS_WIDGET (source) &&
gtk_widget_get_parent (GTK_WIDGET (source)) == layout_widget)
{
source_attr = get_child_attribute (self, GTK_WIDGET (source), attr);
}
else if (GTK_IS_CONSTRAINT_GUIDE (source))
{
GtkConstraintGuide *guide;
guide = (GtkConstraintGuide*)g_hash_table_lookup (self->guides, source);
source_attr = gtk_constraint_guide_get_attribute (guide, attr);
}
else
{
g_critical ("Unknown source widget '%p'", source);
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_strength (constraint));
}
static void
update_child_constraint (GtkConstraintLayout *self,
GtkConstraintLayoutChild *child_info,
GtkWidget *child,
int index,
int value)
{
GtkConstraintVariable *var;
int attr[LAST_VALUE] = {
GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT
};
int relation[LAST_VALUE] = {
GTK_CONSTRAINT_RELATION_GE,
GTK_CONSTRAINT_RELATION_GE,
GTK_CONSTRAINT_RELATION_EQ,
GTK_CONSTRAINT_RELATION_EQ
};
if (child_info->values[index] != value)
{
child_info->values[index] = value;
if (child_info->constraints[index])
gtk_constraint_solver_remove_constraint (self->solver,
child_info->constraints[index]);
var = get_child_attribute (self, child, attr[index]);
if (relation[index] == GTK_CONSTRAINT_RELATION_EQ)
{
gtk_constraint_variable_set_value (var, value);
child_info->constraints[index] =
gtk_constraint_solver_add_stay_variable (self->solver,
var,
GTK_CONSTRAINT_STRENGTH_MEDIUM);
}
else
{
child_info->constraints[index] =
gtk_constraint_solver_add_constraint (self->solver,
var,
relation[index],
gtk_constraint_expression_new (value),
GTK_CONSTRAINT_STRENGTH_REQUIRED);
}
}
}
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 min_value;
int nat_value;
solver = gtk_constraint_layout_get_solver (self);
if (solver == NULL)
return;
gtk_constraint_solver_freeze (solver);
/* 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 *info;
GtkRequisition min_req, nat_req;
if (!gtk_widget_should_layout (child))
continue;
gtk_widget_get_preferred_size (child, &min_req, &nat_req);
info = GTK_CONSTRAINT_LAYOUT_CHILD (gtk_layout_manager_get_layout_child (manager, child));
update_child_constraint (self, info, child, MIN_WIDTH, min_req.width);
update_child_constraint (self, info, child, MIN_HEIGHT, min_req.height);
update_child_constraint (self, info, child, NAT_WIDTH, nat_req.width);
update_child_constraint (self, info, child, NAT_HEIGHT, nat_req.height);
}
gtk_constraint_solver_thaw (solver);
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);
nat_value = gtk_constraint_variable_get_value (size);
/* 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_STRENGTH_STRONG * 2);
if (for_size > 0)
gtk_constraint_solver_add_edit_variable (solver, opposite_size, GTK_CONSTRAINT_STRENGTH_STRONG * 2);
gtk_constraint_solver_begin_edit (solver);
gtk_constraint_solver_suggest_value (solver, size, 0.0);
if (for_size > 0)
gtk_constraint_solver_suggest_value (solver, opposite_size, for_size);
gtk_constraint_solver_resolve (solver);
min_value = gtk_constraint_variable_get_value (size);
gtk_constraint_solver_remove_edit_variable (solver, size);
if (for_size > 0)
gtk_constraint_solver_remove_edit_variable (solver, opposite_size);
gtk_constraint_solver_end_edit (solver);
GTK_NOTE (LAYOUT,
g_print ("layout %p %s size: min %d nat %d (for opposite size: %d)\n",
self,
orientation == GTK_ORIENTATION_HORIZONTAL ? "horizontal" : "vertical",
min_value, nat_value,
for_size));
if (minimum != NULL)
*minimum = min_value;
if (natural != NULL)
*natural = nat_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_STRENGTH_REQUIRED);
gtk_constraint_variable_set_value (layout_left, 0.0);
stay_l = gtk_constraint_solver_add_stay_variable (solver,
layout_left,
GTK_CONSTRAINT_STRENGTH_REQUIRED);
gtk_constraint_variable_set_value (layout_width, width);
stay_w = gtk_constraint_solver_add_stay_variable (solver,
layout_width,
GTK_CONSTRAINT_STRENGTH_REQUIRED);
gtk_constraint_variable_set_value (layout_height, height);
stay_h = gtk_constraint_solver_add_stay_variable (solver,
layout_height,
GTK_CONSTRAINT_STRENGTH_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)));
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;
GtkAllocation child_alloc;
int child_baseline = -1;
if (!gtk_widget_should_layout (child))
continue;
/* Retrieve all the values associated with the child */
var_top = get_child_attribute (self, child, GTK_CONSTRAINT_ATTRIBUTE_TOP);
var_left = get_child_attribute (self, child, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
var_width = get_child_attribute (self, child, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
var_height = get_child_attribute (self, child, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
var_baseline = get_child_attribute (self, 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);
}
#ifdef G_ENABLE_DEBUG
if (GTK_DEBUG_CHECK (LAYOUT))
{
GHashTableIter iter;
gpointer key;
g_hash_table_iter_init (&iter, self->guides);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraintGuide *guide = key;
GtkConstraintVariable *var_top, *var_left, *var_width, *var_height;
var_top = gtk_constraint_guide_get_attribute (guide, GTK_CONSTRAINT_ATTRIBUTE_TOP);
var_left = gtk_constraint_guide_get_attribute (guide, GTK_CONSTRAINT_ATTRIBUTE_LEFT);
var_width = gtk_constraint_guide_get_attribute (guide, GTK_CONSTRAINT_ATTRIBUTE_WIDTH);
var_height = gtk_constraint_guide_get_attribute (guide, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT);
g_print ("Allocating guide '%s'[%p] with { .x: %g .y: %g .w: %g .h: %g }\n",
gtk_constraint_guide_get_name (guide), guide,
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));
}
}
#endif
/* 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);
}
g_hash_table_iter_init (&iter, self->guides);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraintGuide *guide = key;
gtk_constraint_guide_update (guide);
}
}
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);
}
g_hash_table_iter_init (&iter, self->guides);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraintGuide *guide = key;
gtk_constraint_guide_detach (guide);
}
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);
self->guides =
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:
* @layout: a #GtkConstraintLayout
* @constraint: (transfer full): a #GtkConstraint
*
* Adds a #GtkConstraint to the layout manager.
*
* The #GtkConstraint:source and #GtkConstraint:target
* properties of @constraint can be:
*
* - set to %NULL to indicate that the constraint refers to the
* widget using @layout
* - set to the #GtkWidget using @layout
* - set to a child of the #GtkWidget using @layout
* - set to a guide that is part of @layout
*
* The @layout acquires the ownership of @constraint after calling
* this function.
*/
void
gtk_constraint_layout_add_constraint (GtkConstraintLayout *layout,
GtkConstraint *constraint)
{
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout));
g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
g_return_if_fail (!gtk_constraint_is_attached (constraint));
layout_add_constraint (layout, constraint);
g_hash_table_add (layout->constraints, constraint);
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
}
/**
* gtk_constraint_layout_remove_constraint:
* @layout: 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 *layout,
GtkConstraint *constraint)
{
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout));
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 (layout->constraints, constraint);
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
}
/**
* gtk_constraint_layout_remove_all_constraints:
* @layout: a #GtkConstraintLayout
*
* Removes all constraints from the layout manager.
*/
void
gtk_constraint_layout_remove_all_constraints (GtkConstraintLayout *layout)
{
GHashTableIter iter;
gpointer key;
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout));
g_hash_table_iter_init (&iter, layout->constraints);
while (g_hash_table_iter_next (&iter, &key, NULL))
{
GtkConstraint *constraint = key;
gtk_constraint_detach (constraint);
g_hash_table_iter_remove (&iter);
}
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
}
/**
* gtk_constraint_layout_add_guide:
* @layout: a #GtkConstraintLayout
* @guide: (transfer full): a #GtkConstraintGuide object
*
* Adds a guide to @layout. A guide can be used as
* the source or target of constraints, like a widget,
* but it is not visible.
*
* The @layout acquires the ownership of @guide after calling
* this function.
*/
void
gtk_constraint_layout_add_guide (GtkConstraintLayout *layout,
GtkConstraintGuide *guide)
{
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout));
g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
g_return_if_fail (gtk_constraint_guide_get_layout (guide) == NULL);
gtk_constraint_guide_set_layout (guide, layout);
g_hash_table_add (layout->guides, guide);
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
}
/**
* gtk_constraint_layout_remove_guide:
* @layout: a #GtkConstraintManager
* @guide: a #GtkConstraintGuide object
*
* Removes @guide from the layout manager,
* so that it no longer influences the layout.
*/
void
gtk_constraint_layout_remove_guide (GtkConstraintLayout *layout,
GtkConstraintGuide *guide)
{
g_return_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout));
g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
g_return_if_fail (gtk_constraint_guide_get_layout (guide) == layout);
gtk_constraint_guide_detach (guide);
gtk_constraint_guide_set_layout (guide, NULL);
g_hash_table_remove (layout->guides, guide);
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
}
static GtkConstraintAttribute
attribute_from_name (const char *name)
{
if (name == NULL || *name == '\0')
return GTK_CONSTRAINT_ATTRIBUTE_NONE;
/* We sadly need to special case these two because the name does
* not match the VFL grammar rules
*/
if (strcmp (name, "centerX") == 0)
return GTK_CONSTRAINT_ATTRIBUTE_CENTER_X;
if (strcmp (name, "centerY") == 0)
return GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y;
for (int i = 0; i < G_N_ELEMENTS (attribute_names); i++)
{
if (strcmp (attribute_names[i], name) == 0)
return i;
}
return GTK_CONSTRAINT_ATTRIBUTE_NONE;
}
GQuark
gtk_constraint_vfl_parser_error_quark (void)
{
return g_quark_from_static_string ("gtk-constraint-vfl-parser-error-quark");
}
/**
* gtk_constraint_layout_add_constraints_from_descriptionv: (rename-to gtk_constraint_layout_add_constraints_from_description)
* @layout: a #GtkConstraintLayout
* @lines: (array length=n_lines): an array of Visual Format Language lines
* defining a set of constraints
* @n_lines: the number of lines
* @hspacing: default horizontal spacing value, or -1 for the fallback value
* @vspacing: default vertical spacing value, or -1 for the fallback value
* @views: (element-type utf8 Gtk.ConstraintTarget): a dictionary of [ name, target ]
* pairs; the `name` keys map to the view names in the VFL lines, while
* the `target` values map to children of the widget using a #GtkConstraintLayout, or guides
* @error: return location for a #GError
*
* Creates a list of constraints from a formal description using a compact
* description syntax called VFL, or "Visual Format Language".
*
* The Visual Format Language is based on Apple's AutoLayout [VFL](https://developer.apple.com/library/content/documentation/UserExperience/Conceptual/AutolayoutPG/VisualFormatLanguage.html).
*
* The @views dictionary is used to match #GtkConstraintTargets to the symbolic
* view name inside the VFL.
*
* The VFL grammar is:
*
* |[<!-- language="plain" -->
* <visualFormatString> = (<orientation>)?
* (<superview><connection>)?
* <view>(<connection><view>)*
* (<connection><superview>)?
* <orientation> = 'H' | 'V'
* <superview> = '|'
* <connection> = '' | '-' <predicateList> '-' | '-'
* <predicateList> = <simplePredicate> | <predicateListWithParens>
* <simplePredicate> = <metricName> | <positiveNumber>
* <predicateListWithParens> = '(' <predicate> (',' <predicate>)* ')'
* <predicate> = (<relation>)? <objectOfPredicate> (<operatorList>)? ('@' <priority>)?
* <relation> = '==' | '<=' | '>='
* <objectOfPredicate> = <constant> | <viewName> | ('.' <attributeName>)?
* <priority> = <positiveNumber> | 'required' | 'strong' | 'medium' | 'weak'
* <constant> = <number>
* <operatorList> = (<multiplyOperator>)? (<addOperator>)?
* <multiplyOperator> = [ '*' | '/' ] <positiveNumber>
* <addOperator> = [ '+' | '-' ] <positiveNumber>
* <viewName> = [A-Za-z_]([A-Za-z0-9_]*) // A C identifier
* <metricName> = [A-Za-z_]([A-Za-z0-9_]*) // A C identifier
* <attributeName> = 'top' | 'bottom' | 'left' | 'right' | 'width' | 'height' |
* 'start' | 'end' | 'centerX' | 'centerY' | 'baseline'
* <positiveNumber> // A positive real number parseable by g_ascii_strtod()
* <number> // A real number parseable by g_ascii_strtod()
* ]|
*
* **Note**: The VFL grammar used by GTK is slightly different than the one
* defined by Apple, as it can use symbolic values for the constraint's
* strength instead of numeric values; additionally, GTK allows adding
* simple arithmetic operations inside predicates.
*
* Examples of VFL descriptions are:
*
* |[<!-- language="plain" -->
* // Default spacing
* [button]-[textField]
*
* // Width constraint
* [button(>=50)]
*
* // Connection to super view
* |-50-[purpleBox]-50-|
*
* // Vertical layout
* V:[topField]-10-[bottomField]
*
* // Flush views
* [maroonView][blueView]
*
* // Priority
* [button(100@strong)]
*
* // Equal widths
* [button1(==button2)]
*
* // Multiple predicates
* [flexibleButton(>=70,<=100)]
*
* // A complete line of layout
* |-[find]-[findNext]-[findField(>=20)]-|
*
* // Operators
* [button1(button2 / 3 + 50)]
*
* // Named attributes
* [button1(==button2.height)]
* ]|
*
* Returns: (transfer container) (element-type GtkConstraint): the list of
* #GtkConstraints that were added to the layout
*/
GList *
gtk_constraint_layout_add_constraints_from_descriptionv (GtkConstraintLayout *layout,
const char * const lines[],
gsize n_lines,
int hspacing,
int vspacing,
GHashTable *views,
GError **error)
{
GtkConstraintVflParser *parser;
GList *res = NULL;
g_return_val_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout), NULL);
g_return_val_if_fail (lines != NULL, NULL);
g_return_val_if_fail (views != NULL, NULL);
g_return_val_if_fail (error == NULL || *error == NULL, NULL);
parser = gtk_constraint_vfl_parser_new ();
gtk_constraint_vfl_parser_set_default_spacing (parser, hspacing, vspacing);
gtk_constraint_vfl_parser_set_views (parser, views);
for (gsize i = 0; i < n_lines; i++)
{
const char *line = lines[i];
GError *internal_error = NULL;
gtk_constraint_vfl_parser_parse_line (parser, line, -1, &internal_error);
if (internal_error != NULL)
{
int offset = gtk_constraint_vfl_parser_get_error_offset (parser);
int range = gtk_constraint_vfl_parser_get_error_range (parser);
char *squiggly = NULL;
if (range > 0)
{
squiggly = g_new (char, range + 1);
for (int r = 0; r < range; i++)
squiggly[r] = '~';
squiggly[range] = '\0';
}
g_set_error (error, GTK_CONSTRAINT_VFL_PARSER_ERROR,
internal_error->code,
"%" G_GSIZE_FORMAT ":%d: %s\n"
"%s\n"
"%*s^%s",
i, offset + 1,
internal_error->message,
line,
offset, " ", squiggly != NULL ? squiggly : "");
g_free (squiggly);
g_error_free (internal_error);
gtk_constraint_vfl_parser_free (parser);
return res;
}
int n_constraints = 0;
GtkConstraintVfl *constraints = gtk_constraint_vfl_parser_get_constraints (parser, &n_constraints);
for (int j = 0; j < n_constraints; j++)
{
const GtkConstraintVfl *c = &constraints[j];
gpointer source, target;
GtkConstraintAttribute source_attr, target_attr;
target = g_hash_table_lookup (views, c->view1);
target_attr = attribute_from_name (c->attr1);
if (c->view2 != NULL)
source = g_hash_table_lookup (views, c->view2);
else
source = NULL;
if (c->attr2 != NULL)
source_attr = attribute_from_name (c->attr2);
else
source_attr = GTK_CONSTRAINT_ATTRIBUTE_NONE;
GtkConstraint *constraint =
gtk_constraint_new (target, target_attr,
c->relation,
source, source_attr,
c->multiplier,
c->constant,
c->strength);
layout_add_constraint (layout, constraint);
g_hash_table_add (layout->constraints, constraint);
res = g_list_prepend (res, constraint);
}
g_free (constraints);
}
gtk_constraint_vfl_parser_free (parser);
gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
return res;
}
/**
* gtk_constraint_layout_add_constraints_from_description:
* @layout: a #GtkConstraintLayout
* @lines: (array length=n_lines): an array of Visual Format Language lines
* defining a set of constraints
* @n_lines: the number of lines
* @hspacing: default horizontal spacing value, or -1 for the fallback value
* @vspacing: default vertical spacing value, or -1 for the fallback value
* @error: return location for a #GError
* @first_view: the name of a view in the VFL description, followed by the
* #GtkConstraintTarget to which it maps
* @...: a %NULL-terminated list of view names and #GtkConstraintTargets
*
* Creates a list of constraints they formal description using a compact
* description syntax called VFL, or "Visual Format Language".
*
* This function is a convenience wrapper around
* gtk_constraint_layout_add_constraints_from_descriptionv(), using
* variadic arguments to populate the view/target map.
*
* Returns: (transfer container) (element-type GtkConstraint): the list of
* #GtkConstraints that were added to the layout
*/
GList *
gtk_constraint_layout_add_constraints_from_description (GtkConstraintLayout *layout,
const char * const lines[],
gsize n_lines,
int hspacing,
int vspacing,
GError **error,
const char *first_view,
...)
{
GtkConstraintVflParser *parser;
GHashTable *views;
const char *view;
GList *res;
va_list args;
g_return_val_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout), NULL);
g_return_val_if_fail (lines != NULL, NULL);
g_return_val_if_fail (error == NULL || *error == NULL, NULL);
g_return_val_if_fail (first_view != NULL, NULL);
parser = gtk_constraint_vfl_parser_new ();
gtk_constraint_vfl_parser_set_default_spacing (parser, hspacing, vspacing);
views = g_hash_table_new (g_str_hash, g_str_equal);
va_start (args, first_view);
view = first_view;
while (view != NULL)
{
GtkConstraintTarget *target = va_arg (args, GtkConstraintTarget *);
if (target == NULL)
break;
g_hash_table_insert (views, (gpointer) view, target);
view = va_arg (args, const char *);
}
va_end (args);
res =
gtk_constraint_layout_add_constraints_from_descriptionv (layout, lines, n_lines,
hspacing, vspacing,
views,
error);
g_hash_table_unref (views);
return res;
}
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