An index widget gives you an index for fast access to whichever group of other UI items you have. By default hidden, the index appears when the user clicks over its reserved area in the canvas. In the default theme, it is a one finger wide area on the right side of the index widget's container. Generally, an index is used together with lists, generic lists or generic grids.

• Adding a Index
• Adding Items
• Sorting Index Items
• Using Index Callbacks

• Index Widget API

Call elm_index_add() to create a new index widget.

Evas_Object *index;
index = elm_index_add(parent);

Here we add the listitem object at the letter “A”, calling the smart callback it_select_cb() when this item is selected.

Elm_Object_Item *list_item1, *list_item2;
elm_index_item_append(index, "A", _it_select_cb, list_item1);

This is how to define the smart callback.

// Callback function called when the list_item1 object
// is selected
static void
_it_select_cb(void *data, Evas_Object *obj, void *event_info)
{
   printf("Item1 selected\n");
}

In the previous case, the indexes are appended to the existing ones. It is also possible to prepend index items with elm_index_item_prepend().

We can insert index items using a sorting function. Indexes can be sorted, for example, by alphabetic order.

We must write a compare function that returns a positive int, 0 or a negative int when the data2 item parameter is respectively greater than, equal to or lower than the data1 parameter.

static int
_index_icmp(const void *data1, const void *data2)
{
   int result;
   // Code that does the item comparison will be written here
   return result;
}

We add a new item at the “B” index using the compare function to sort the indexes.

elm_index_item_sorted_insert(index, "B", NULL, list_item2, _index_icmp, NULL);

This widget emits the following signals, besides the ones sent from Layout:

• “changed” - When the selected index item changes. event_info is the selected item's data pointer.
• “delay,changed” - When the selected index item changes, but after a small idling period. event_info is the selected item's data pointer.
• “selected” - When the user releases a mouse button and selects an item. event_info is the selected item's pointer.
• “level,up” - when the user moves a finger from the first level to the second level
• “level,down” - when the user moves a finger from the second level to the first level
• “language,changed” - the program's language changed
• “focused” - When the index has received focus. (since 1.8)
• “unfocused” - When the index has lost focus. (since 1.8)

The “delay,changed” event is so that it'll wait a small time before actually reporting those events and, moreover, just the last event happening on those time frames will actually be reported.

When the user selects an item in the index, the “selected” signal is emitted. The developer can then implement the associated callback to do the appropriate action (to show a given area or child object depending on the index item selected, for example). Here is an example of such a callback.

static void
_index_selected_cb(void *data, Evas_Object *obj, void *event_info)
{
   Elm_Object_Item *lit = event_info;
   // Code that does the desired action
}

Then we register this callback to the “selected” signal.

evas_object_smart_callback_add(index, "selected", _index_selected_cb, NULL);