[gnome-builder] greeter: add helper truncation model

[Christian Hergert <chergert src gnome org>]

commit bd5cd1622190be7cdcfd289e6105fd2824a16886
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 21 22:36:43 2019 -0800

    greeter: add helper truncation model
    
    This model is convenient for adding view-more rows to GtkListBox. It can
    filter to a fixed number of rows, and then expand them when the expanded
    mode is set.

 src/libide/greeter/ide-truncate-model.c | 333 ++++++++++++++++++++++++++++++++
 src/libide/greeter/ide-truncate-model.h |  40 ++++
 src/libide/greeter/meson.build          |   2 +
 3 files changed, 375 insertions(+)
---
diff --git a/src/libide/greeter/ide-truncate-model.c b/src/libide/greeter/ide-truncate-model.c
new file mode 100644
index 000000000..5d6c0f18a
--- /dev/null
+++ b/src/libide/greeter/ide-truncate-model.c
@@ -0,0 +1,333 @@
+/* ide-truncate-model.c
+ *
+ * Copyright 2019 Christian Hergert <chergert redhat com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#define G_LOG_DOMAIN "ide-truncate-model"
+
+#include "config.h"
+
+#include "ide-truncate-model.h"
+
+#define DEFAULT_MAX_ITEMS 4
+
+struct _IdeTruncateModel
+{
+  GObject     parent_instance;
+  GListModel *child_model;
+  guint       max_items;
+  guint       prev_n_items;
+  guint       expanded : 1;
+};
+
+static gpointer
+ide_truncate_model_get_item (GListModel *model,
+                             guint       position)
+{
+  return g_list_model_get_item (IDE_TRUNCATE_MODEL (model)->child_model, position);
+}
+
+static guint
+ide_truncate_model_get_n_items (GListModel *model)
+{
+  IdeTruncateModel *self = (IdeTruncateModel *)model;
+  guint n_items = g_list_model_get_n_items (IDE_TRUNCATE_MODEL (model)->child_model);
+  return self->expanded ? n_items : MIN (n_items, self->max_items);
+}
+
+static GType
+ide_truncate_model_get_item_type (GListModel *model)
+{
+  return g_list_model_get_item_type (IDE_TRUNCATE_MODEL (model)->child_model);
+}
+
+static void
+list_model_iface_init (GListModelInterface *iface)
+{
+  iface->get_item = ide_truncate_model_get_item;
+  iface->get_n_items = ide_truncate_model_get_n_items;
+  iface->get_item_type = ide_truncate_model_get_item_type;
+}
+
+G_DEFINE_TYPE_WITH_CODE (IdeTruncateModel, ide_truncate_model, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, list_model_iface_init))
+
+enum {
+  PROP_0,
+  PROP_CHILD_MODEL,
+  PROP_EXPANDED,
+  PROP_MAX_ITEMS,
+  N_PROPS
+};
+
+static GParamSpec *properties [N_PROPS];
+
+/**
+ * ide_truncate_model_new:
+ * @child_model: a #GListModel
+ *
+ * Create a new #IdeTruncateModel that wraps @child_model. Only
+ * #IdeTruncateModel:max-items will be displayed until
+ * #IdeTrunicateModel:expanded is set.
+ *
+ * Returns: (transfer full): a newly created #IdeTruncateModel
+ */
+IdeTruncateModel *
+ide_truncate_model_new (GListModel *child_model)
+{
+  g_return_val_if_fail (G_IS_LIST_MODEL (child_model), NULL);
+
+  return g_object_new (IDE_TYPE_TRUNCATE_MODEL,
+                       "child-model", child_model,
+                       NULL);
+}
+
+static void
+ide_truncate_model_items_changed_cb (IdeTruncateModel *self,
+                                     guint             position,
+                                     guint             removed,
+                                     guint             added,
+                                     GListModel       *model)
+{
+  guint n_items;
+
+  g_assert (IDE_IS_TRUNCATE_MODEL (self));
+  g_assert (G_IS_LIST_MODEL (model));
+
+  n_items = g_list_model_get_n_items (model);
+
+  if (self->expanded)
+    {
+      g_list_model_items_changed (G_LIST_MODEL (self), position, removed, added);
+    }
+  else
+    {
+      if (position < (self->max_items - 1))
+        {
+          g_list_model_items_changed (G_LIST_MODEL (self),
+                                      0,
+                                      self->prev_n_items,
+                                      MIN (n_items, self->max_items));
+        }
+    }
+
+  self->prev_n_items = n_items;
+}
+
+static void
+ide_truncate_model_finalize (GObject *object)
+{
+  IdeTruncateModel *self = (IdeTruncateModel *)object;
+
+  g_clear_object (&self->child_model);
+
+  G_OBJECT_CLASS (ide_truncate_model_parent_class)->finalize (object);
+}
+
+static void
+ide_truncate_model_get_property (GObject    *object,
+                                 guint       prop_id,
+                                 GValue     *value,
+                                 GParamSpec *pspec)
+{
+  IdeTruncateModel *self = IDE_TRUNCATE_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_CHILD_MODEL:
+      g_value_set_object (value, ide_truncate_model_get_child_model (self));
+      break;
+
+    case PROP_MAX_ITEMS:
+      g_value_set_uint (value, ide_truncate_model_get_max_items (self));
+      break;
+
+    case PROP_EXPANDED:
+      g_value_set_boolean (value, ide_truncate_model_get_expanded (self));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+ide_truncate_model_set_property (GObject      *object,
+                                 guint         prop_id,
+                                 const GValue *value,
+                                 GParamSpec   *pspec)
+{
+  IdeTruncateModel *self = IDE_TRUNCATE_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_CHILD_MODEL:
+      self->child_model = g_value_dup_object (value);
+      self->prev_n_items = g_list_model_get_n_items (self->child_model);
+      g_signal_connect_object (self->child_model,
+                               "items-changed",
+                               G_CALLBACK (ide_truncate_model_items_changed_cb),
+                               self,
+                               G_CONNECT_SWAPPED);
+      break;
+
+    case PROP_MAX_ITEMS:
+      ide_truncate_model_set_max_items (self, g_value_get_uint (value));
+      break;
+
+    case PROP_EXPANDED:
+      ide_truncate_model_set_expanded (self, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+ide_truncate_model_class_init (IdeTruncateModelClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = ide_truncate_model_finalize;
+  object_class->get_property = ide_truncate_model_get_property;
+  object_class->set_property = ide_truncate_model_set_property;
+
+  /**
+   * IdeTruncateModel:child-model:
+   *
+   * The "child-model" property is the model to be trunicated.
+   */
+  properties [PROP_CHILD_MODEL] =
+    g_param_spec_object ("child-model",
+                         "Child Model",
+                         "Child GListModel",
+                         G_TYPE_LIST_MODEL,
+                         (G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
+
+  properties [PROP_MAX_ITEMS] =
+    g_param_spec_uint ("max-items",
+                       "Max Items",
+                       "Max items to display when not expanded",
+                       0, G_MAXUINT, DEFAULT_MAX_ITEMS,
+                       (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  properties [PROP_EXPANDED] =
+    g_param_spec_boolean ("expanded",
+                          "Expanded",
+                          "If all the items should be displayed",
+                          FALSE,
+                          (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_properties (object_class, N_PROPS, properties);
+}
+
+static void
+ide_truncate_model_init (IdeTruncateModel *self)
+{
+  self->max_items = DEFAULT_MAX_ITEMS;
+}
+
+gboolean
+ide_truncate_model_get_expanded (IdeTruncateModel *self)
+{
+  g_return_val_if_fail (IDE_IS_TRUNCATE_MODEL (self), FALSE);
+
+  return self->expanded;
+}
+
+void
+ide_truncate_model_set_expanded (IdeTruncateModel *self,
+                                 gboolean          expanded)
+{
+  g_return_if_fail (IDE_IS_TRUNCATE_MODEL (self));
+
+  expanded = !!expanded;
+
+  if (expanded != self->expanded)
+    {
+      guint n_items = g_list_model_get_n_items (self->child_model);
+      guint old_n_items = self->expanded ? n_items : MIN (n_items, self->max_items);
+      guint new_n_items = expanded ? n_items : MIN (n_items, self->max_items);
+
+      self->expanded = expanded;
+
+      if (new_n_items > old_n_items)
+        g_list_model_items_changed (G_LIST_MODEL (self),
+                                    old_n_items,
+                                    0,
+                                    new_n_items - old_n_items);
+      else
+        g_list_model_items_changed (G_LIST_MODEL (self),
+                                    0, old_n_items, new_n_items);
+
+      g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_EXPANDED]);
+    }
+}
+
+guint
+ide_truncate_model_get_max_items (IdeTruncateModel *self)
+{
+  g_return_val_if_fail (IDE_IS_TRUNCATE_MODEL (self), 0);
+
+  return self->max_items;
+}
+
+void
+ide_truncate_model_set_max_items (IdeTruncateModel *self,
+                                  guint             max_items)
+{
+  g_return_if_fail (IDE_IS_TRUNCATE_MODEL (self));
+
+  if (max_items == 0)
+    max_items = DEFAULT_MAX_ITEMS;
+
+  if (max_items != self->max_items)
+    {
+      guint old_max_items = self->max_items;
+
+      self->max_items = max_items;
+
+      if (!self->expanded)
+        {
+          guint n_items = g_list_model_get_n_items (self->child_model);
+          guint old_n_items = MIN (old_max_items, n_items);
+          guint new_n_items = MIN (max_items, n_items);
+
+          if (old_n_items != new_n_items)
+            g_list_model_items_changed (G_LIST_MODEL (self), 0, old_n_items, new_n_items);
+        }
+
+      g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_MAX_ITEMS]);
+    }
+}
+
+/**
+ * ide_truncate_model_get_child_model:
+ *
+ * Gets the #IdeTruncateModel:child-model property.
+ *
+ * Returns: (transfer none): a #GListModel
+ */
+GListModel *
+ide_truncate_model_get_child_model (IdeTruncateModel *self)
+{
+  g_return_val_if_fail (IDE_IS_TRUNCATE_MODEL (self), NULL);
+
+  return self->child_model;
+}
diff --git a/src/libide/greeter/ide-truncate-model.h b/src/libide/greeter/ide-truncate-model.h
new file mode 100644
index 000000000..dcd8af27c
--- /dev/null
+++ b/src/libide/greeter/ide-truncate-model.h
@@ -0,0 +1,40 @@
+/* ide-truncate-model.h
+ *
+ * Copyright 2019 Christian Hergert <chergert redhat com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <gio/gio.h>
+
+G_BEGIN_DECLS
+
+#define IDE_TYPE_TRUNCATE_MODEL (ide_truncate_model_get_type())
+
+G_DECLARE_FINAL_TYPE (IdeTruncateModel, ide_truncate_model, IDE, TRUNCATE_MODEL, GObject)
+
+IdeTruncateModel *ide_truncate_model_new             (GListModel       *child_model);
+GListModel       *ide_truncate_model_get_child_model (IdeTruncateModel *self);
+guint             ide_truncate_model_get_max_items   (IdeTruncateModel *self);
+void              ide_truncate_model_set_max_items   (IdeTruncateModel *self,
+                                                      guint             max_items);
+gboolean          ide_truncate_model_get_expanded    (IdeTruncateModel *self);
+void              ide_truncate_model_set_expanded    (IdeTruncateModel *self,
+                                                      gboolean          expanded);
+
+G_END_DECLS
diff --git a/src/libide/greeter/meson.build b/src/libide/greeter/meson.build
index 033137758..43dd2df5d 100644
--- a/src/libide/greeter/meson.build
+++ b/src/libide/greeter/meson.build
@@ -17,6 +17,7 @@ libide_greeter_public_headers = [
 
 libide_greeter_private_headers = [
   'ide-greeter-private.h',
+  'ide-truncate-model.h',
 ]
 
 install_headers(libide_greeter_public_headers, subdir: libide_greeter_header_subdir)
@@ -36,6 +37,7 @@ libide_greeter_private_sources = [
   'ide-greeter-workspace-actions.c',
   'ide-greeter-workspace-shortcuts.c',
   'ide-greeter-buttons-section.c',
+  'ide-truncate-model.c',
 ]
 
 #