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constraint editor: Allow dragging children

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We add a weak constraint for the position
and update it as the widget is dragged.
This commit is contained in:
Matthias Clasen 2019-07-01 04:24:26 +00:00
parent 658397fad0
commit 48e6cd4255
1 changed files with 103 additions and 2 deletions
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105
demos/constraint-editor/constraint-view.c
View File

@ -22,6 +22,8 @@ struct _ConstraintView
GtkWidget parent;
GListStore *store;
GtkWidget *drag_widget;
};
G_DEFINE_TYPE (ConstraintView, constraint_view, GTK_TYPE_WIDGET);
@ -51,13 +53,109 @@ constraint_view_class_init (ConstraintViewClass *klass)
gtk_widget_class_set_css_name (widget_class, "constraintview");
}
static void
update_weak_position (ConstraintView *self,
GtkWidget *child,
double x,
double y)
{
GtkLayoutManager *manager;
GtkConstraint *constraint;
manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
constraint = (GtkConstraint *)g_object_get_data (G_OBJECT (child), "x-constraint");
if (constraint)
{
gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
constraint);
g_object_set_data (G_OBJECT (child), "x-constraint", NULL);
}
constraint = gtk_constraint_new_constant (child,
GTK_CONSTRAINT_ATTRIBUTE_CENTER_X,
GTK_CONSTRAINT_RELATION_EQ,
x,
GTK_CONSTRAINT_STRENGTH_WEAK);
gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
constraint);
g_object_set_data (G_OBJECT (child), "x-constraint", constraint);
constraint = (GtkConstraint *)g_object_get_data (G_OBJECT (child), "y-constraint");
if (constraint)
{
gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
constraint);
g_object_set_data (G_OBJECT (child), "y-constraint", NULL);
}
constraint = gtk_constraint_new_constant (child,
GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y,
GTK_CONSTRAINT_RELATION_EQ,
y,
GTK_CONSTRAINT_STRENGTH_WEAK);
gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
constraint);
g_object_set_data (G_OBJECT (child), "y-constraint", constraint);
}
static void
drag_begin (GtkGestureDrag *drag,
double start_x,
double start_y,
ConstraintView *self)
{
GtkWidget *widget;
widget = gtk_widget_pick (GTK_WIDGET (self), start_x, start_y, GTK_PICK_DEFAULT);
if (GTK_IS_LABEL (widget))
{
widget = gtk_widget_get_ancestor (widget, GTK_TYPE_FRAME);
if (widget &&
gtk_widget_get_parent (widget) == (GtkWidget *)self)
{
self->drag_widget = widget;
}
}
}
static void
drag_update (GtkGestureDrag *drag,
double offset_x,
double offset_y,
ConstraintView *self)
{
double x, y;
if (!self->drag_widget)
return;
gtk_gesture_drag_get_start_point (drag, &x, &y);
update_weak_position (self, self->drag_widget, x + offset_x, y + offset_y);
}
static void
drag_end (GtkGestureDrag *drag,
double offset_x,
double offset_y,
ConstraintView *self)
{
self->drag_widget = NULL;
}
static void
constraint_view_init (ConstraintView *self)
{
GtkEventController *controller;
gtk_widget_set_layout_manager (GTK_WIDGET (self),
gtk_constraint_layout_new ());
self->store = g_list_store_new (G_TYPE_OBJECT);
controller = (GtkEventController *)gtk_gesture_drag_new ();
g_signal_connect (controller, "drag-begin", G_CALLBACK (drag_begin), self);
g_signal_connect (controller, "drag-update", G_CALLBACK (drag_update), self);
g_signal_connect (controller, "drag-end", G_CALLBACK (drag_end), self);
gtk_widget_add_controller (GTK_WIDGET (self), controller);
}
ConstraintView *
@ -80,6 +178,8 @@ constraint_view_add_child (ConstraintView *view,
gtk_container_add (GTK_CONTAINER (frame), label);
gtk_widget_set_parent (frame, GTK_WIDGET (view));
update_weak_position (view, frame, 100, 100);
g_list_store_append (view->store, frame);
}
@ -118,7 +218,7 @@ constraint_view_add_guide (ConstraintView *view,
gtk_style_context_add_class (gtk_widget_get_style_context (frame), "guide");
g_object_set_data_full (G_OBJECT (frame), "name", g_strdup (name), g_free);
gtk_container_add (GTK_CONTAINER (frame), label);
gtk_widget_set_parent (frame, GTK_WIDGET (view));
gtk_widget_insert_after (frame, GTK_WIDGET (view), NULL);
g_object_set_data (G_OBJECT (guide), "frame", frame);
g_object_set_data (G_OBJECT (guide), "label", label);
@ -169,9 +269,10 @@ constraint_view_add_guide (ConstraintView *view,
GTK_CONSTRAINT_STRENGTH_REQUIRED);
gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
constraint);
g_object_set_data (G_OBJECT (guide), "height-constraint", constraint);
update_weak_position (view, frame, 150, 150);
g_list_store_append (view->store, guide);
}