Add a constraint editor demo

This is an initial cut at providing a tool
for interactive exploration of constraints.

1 files changed, 277 insertions, 0 deletions

diff --git a/demos/constraint-editor/constraint-view.c b/demos/constraint-editor/constraint-view.c
new file mode 100644
index 0000000000..eb5852a94c
--- /dev/null
+++ b/demos/constraint-editor/constraint-view.c
@@ -0,0 +1,277 @@
+/* Copyright (C) 2019 Red Hat, Inc.
+ *
+ * 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 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/>.
+ */
+
+#include <gtk/gtk.h>
+#include "constraint-view.h"
+
+struct _ConstraintView
+{
+  GtkWidget parent;
+
+  GListStore *store;
+};
+
+G_DEFINE_TYPE (ConstraintView, constraint_view, GTK_TYPE_WIDGET);
+
+static void
+constraint_view_dispose (GObject *object)
+{
+  ConstraintView *view = CONSTRAINT_VIEW (object);
+  GtkWidget *child;
+
+  while ((child = gtk_widget_get_first_child (GTK_WIDGET (view))) != NULL)
+    gtk_widget_unparent (child);
+
+  g_clear_object (&view->store);
+
+  G_OBJECT_CLASS (constraint_view_parent_class)->dispose (object);
+}
+
+static void
+constraint_view_class_init (ConstraintViewClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose = constraint_view_dispose;
+
+  gtk_widget_class_set_css_name (widget_class, "constraintview");
+}
+
+static void
+constraint_view_init (ConstraintView *self)
+{
+  gtk_widget_set_layout_manager (GTK_WIDGET (self),
+                                 gtk_constraint_layout_new ());
+
+  self->store = g_list_store_new (G_TYPE_OBJECT);
+}
+
+ConstraintView *
+constraint_view_new (void)
+{
+  return g_object_new (CONSTRAINT_VIEW_TYPE, NULL);
+}
+
+void
+constraint_view_add_child (ConstraintView *view,
+                           const char     *name)
+{
+  GtkWidget *frame;
+  GtkWidget *label;
+
+  label = gtk_label_new (name);
+  frame = gtk_frame_new (NULL);
+  gtk_style_context_add_class (gtk_widget_get_style_context (frame), "child");
+  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));
+
+  g_list_store_append (view->store, frame);
+}
+
+void
+constraint_view_remove_child (ConstraintView *view,
+                              GtkWidget      *child)
+{
+  int i;
+
+  gtk_widget_unparent (child);
+
+  for (i = 0; i < g_list_model_get_n_items (G_LIST_MODEL (view->store)); i++)
+    {
+      if (g_list_model_get_item (G_LIST_MODEL (view->store), i) == (GObject*)child)
+        {
+          g_list_store_remove (view->store, i);
+          break;
+        }
+    }
+}
+
+void
+constraint_view_add_guide (ConstraintView *view,
+                           GtkConstraintGuide *guide)
+{
+  GtkLayoutManager *manager;
+  GtkWidget *frame;
+  GtkWidget *label;
+  const char *name;
+  GtkConstraint *constraint;
+
+  name = (const char *)g_object_get_data (G_OBJECT (guide), "name");
+
+  label = gtk_label_new (name);
+  frame = gtk_frame_new (NULL);
+  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));
+
+  g_object_set_data (G_OBJECT (guide), "frame", frame);
+  g_object_set_data (G_OBJECT (guide), "label", label);
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+  gtk_constraint_layout_add_guide (GTK_CONSTRAINT_LAYOUT (manager),
+                                   g_object_ref (guide));
+
+  constraint = gtk_constraint_new (frame,
+                                   GTK_CONSTRAINT_ATTRIBUTE_LEFT,
+                                   GTK_CONSTRAINT_RELATION_EQ,
+                                   guide,
+                                   GTK_CONSTRAINT_ATTRIBUTE_LEFT,
+                                   1.0, 0.0,
+                                   GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        constraint);
+  g_object_set_data (G_OBJECT (guide), "left-constraint", constraint);
+
+  constraint = gtk_constraint_new (frame,
+                                   GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                                   GTK_CONSTRAINT_RELATION_EQ,
+                                   guide,
+                                   GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                                   1.0, 0.0,
+                                   GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        constraint);
+  g_object_set_data (G_OBJECT (guide), "top-constraint", constraint);
+
+  constraint = gtk_constraint_new (frame,
+                                   GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                                   GTK_CONSTRAINT_RELATION_EQ,
+                                   guide,
+                                   GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                                   1.0, 0.0,
+                                   GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        constraint);
+  g_object_set_data (G_OBJECT (guide), "width-constraint", constraint);
+
+  constraint = gtk_constraint_new (frame,
+                                   GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                                   GTK_CONSTRAINT_RELATION_EQ,
+                                   guide,
+                                   GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                                   1.0, 0.0,
+                                   GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        constraint);
+
+  g_object_set_data (G_OBJECT (guide), "height-constraint", constraint);
+
+  g_list_store_append (view->store, guide);
+}
+
+void
+constraint_view_guide_changed (ConstraintView     *view,
+                               GtkConstraintGuide *guide)
+{
+  GtkWidget *label;
+  const char *name;
+  int i;
+
+  name = (const char *)g_object_get_data (G_OBJECT (guide), "name");
+  label = (GtkWidget *)g_object_get_data (G_OBJECT (guide), "label");
+  gtk_label_set_label (GTK_LABEL (label), name);
+
+  for (i = 0; i < g_list_model_get_n_items (G_LIST_MODEL (view->store)); i++)
+    {
+      if (g_list_model_get_item (G_LIST_MODEL (view->store), i) == (GObject*)guide)
+        {
+          g_list_model_items_changed (G_LIST_MODEL (view->store), i, 1, 1);
+          break;
+        }
+    }
+}
+
+void
+constraint_view_remove_guide (ConstraintView     *view,
+                              GtkConstraintGuide *guide)
+{
+  GtkLayoutManager *manager;
+  GtkWidget *frame;
+  GtkConstraint *constraint;
+  int i;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+
+  constraint = (GtkConstraint*)g_object_get_data (G_OBJECT (guide), "left-constraint");
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+  constraint = (GtkConstraint*)g_object_get_data (G_OBJECT (guide), "top-constraint");
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+  constraint = (GtkConstraint*)g_object_get_data (G_OBJECT (guide), "width-constraint");
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+  constraint = (GtkConstraint*)g_object_get_data (G_OBJECT (guide), "height-constraint");
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+
+  frame = (GtkWidget *)g_object_get_data (G_OBJECT (guide), "frame");
+  gtk_widget_unparent (frame);
+
+  gtk_constraint_layout_remove_guide (GTK_CONSTRAINT_LAYOUT (manager),
+                                      guide);
+
+  for (i = 0; i < g_list_model_get_n_items (G_LIST_MODEL (view->store)); i++)
+    {
+      if (g_list_model_get_item (G_LIST_MODEL (view->store), i) == (GObject*)guide)
+        {
+          g_list_store_remove (view->store, i);
+          break;
+        }
+    }
+}
+
+void
+constraint_view_add_constraint (ConstraintView *view,
+                                GtkConstraint  *constraint)
+{
+  GtkLayoutManager *manager;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        g_object_ref (constraint));
+
+  g_list_store_append (view->store, constraint);
+}
+
+void
+constraint_view_remove_constraint (ConstraintView *view,
+                                   GtkConstraint  *constraint)
+{
+  GtkLayoutManager *manager;
+  int i;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+  for (i = 0; i < g_list_model_get_n_items (G_LIST_MODEL (view->store)); i++)
+    {
+      if (g_list_model_get_item (G_LIST_MODEL (view->store), i) == (GObject*)constraint)
+        {
+          g_list_store_remove (view->store, i);
+          break;
+        }
+    }
+}
+
+GListModel *
+constraint_view_get_model (ConstraintView *view)
+{
+  return G_LIST_MODEL (view->store);
+}