[gnome-builder/gnome-builder-3-18] tree: add GbTreeNode:children-possible property

[Christian Hergert <chergert src gnome org>]

commit 79c1e52258f0e3d6ac8c0537b5d23cb4c96efee0
Author: Christian Hergert <christian hergert me>
Date:   Sat Sep 26 16:12:13 2015 -0700

    tree: add GbTreeNode:children-possible property
    
    This is about optimizing building of the tree by being lazy. Just export
    it as a property so bindings can use it more easily.

 src/tree/gb-tree-node.c |   37 +++++++++++++++++++++++++++++++++++++
 src/tree/gb-tree-node.h |    1 +
 2 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/src/tree/gb-tree-node.c b/src/tree/gb-tree-node.c
index b30545d..170085a 100644
--- a/src/tree/gb-tree-node.c
+++ b/src/tree/gb-tree-node.c
@@ -50,6 +50,7 @@ G_DEFINE_TYPE (GbTreeNode, gb_tree_node, G_TYPE_INITIALLY_UNOWNED)
 
 enum {
   PROP_0,
+  PROP_CHILDREN_POSSIBLE,
   PROP_ICON_NAME,
   PROP_ITEM,
   PROP_PARENT,
@@ -519,6 +520,10 @@ gb_tree_node_get_property (GObject    *object,
 
   switch (prop_id)
     {
+    case PROP_CHILDREN_POSSIBLE:
+      g_value_set_boolean (value, gb_tree_node_get_children_possible (node));
+      break;
+
     case PROP_ICON_NAME:
       g_value_set_string (value, g_quark_to_string (node->icon_name));
       break;
@@ -562,6 +567,10 @@ gb_tree_node_set_property (GObject      *object,
 
   switch (prop_id)
     {
+    case PROP_CHILDREN_POSSIBLE:
+      gb_tree_node_set_children_possible (node, g_value_get_boolean (value));
+      break;
+
     case PROP_ICON_NAME:
       gb_tree_node_set_icon_name (node, g_value_get_string (value));
       break;
@@ -597,6 +606,26 @@ gb_tree_node_class_init (GbTreeNodeClass *klass)
   object_class->set_property = gb_tree_node_set_property;
 
   /**
+   * GbTreeNode:children-possible:
+   *
+   * This property allows for more lazy loading of nodes.
+   *
+   * When a node becomes visible, we normally build it's children nodes
+   * so that we know if we need an expansion arrow. However, that can
+   * be expensive when rendering directories with lots of subdirectories.
+   *
+   * Using this, you can always show an arrow without building the children
+   * and simply hide the arrow if there were in fact no children (upon
+   * expansion).
+   */
+  gParamSpecs [PROP_CHILDREN_POSSIBLE] =
+    g_param_spec_boolean ("children-possible",
+                          "Children Possible",
+                          "Allows for lazy creation of children nodes.",
+                          FALSE,
+                          (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  /**
    * GbTreeNode:icon-name:
    *
    * An icon-name to display on the row.
@@ -861,6 +890,14 @@ _gb_tree_node_remove_dummy_child (GbTreeNode *self)
     }
 }
 
+gboolean
+gb_tree_node_get_children_possible (GbTreeNode *self)
+{
+  g_return_val_if_fail (GB_IS_TREE_NODE (self), FALSE);
+
+  return self->children_possible;
+}
+
 /**
  * gb_tree_node_set_children_possible:
  * @self: A #GbTreeNode.
diff --git a/src/tree/gb-tree-node.h b/src/tree/gb-tree-node.h
index 47faca3..3af41e7 100644
--- a/src/tree/gb-tree-node.h
+++ b/src/tree/gb-tree-node.h
@@ -58,6 +58,7 @@ const gchar   *gb_tree_node_get_text              (GbTreeNode   *node);
 void           gb_tree_node_set_text              (GbTreeNode   *node,
                                                    const gchar  *text);
 GbTree        *gb_tree_node_get_tree              (GbTreeNode   *node);
+gboolean       gb_tree_node_get_children_possible (GbTreeNode   *self);
 void           gb_tree_node_set_children_possible (GbTreeNode   *self,
                                                    gboolean      children_possible);
 gboolean       gb_tree_node_get_use_markup        (GbTreeNode   *self);