Using IlvStringList

The class IlvStringList displays a list of gadget items of the class IlvGadgetItem, or of a subclass. IlvStringList is a subclass of IlvScrolledGadget and IlvListGadgetItemHolder.

String lists can store up to 32767 items and can be composed of labels, bitmaps, or graphic objects (class IlvGraphic), and support scrollbars.

This section covers the following topics:

Member functions for manipulating string list items are defined in the base class IlvListGadgetItemHolder.

In addition to the graphic features of gadget items (see the class IlvGadgetItem), the class IlvStringList offers several ways to customize the global display of its items:

By default, items in a string list can have different heights. You can however choose to display all the items with the same height using the member function setDefaultItemHeight.

Pictures in a string list can be shown or hidden with the member function showPicture.

Similarly, labels in a string list can be displayed or hidden with the member function showLabel.

By default, a string list displays both labels and pictures.


Note: You can override this global setting for a specific item with showLabel and showPicture.

You can change the position of the item labels relative to their pictures with setLabelPosition.

By default, the label is placed to the right of the picture (IlvRight).


Note: You can override this global setting for a specific item with setLabelPosition.

When the label position is IlvRight (the default value), and when only certain items are using a picture and a label, you may want all the labels to be left-aligned, as illustrated in figure 11.21.

By default, item labels are automatically aligned. When an item is modified, the list recomputes the new label alignment. Since this operation can be time-consuming, it is possible to disable the automatic alignment of labels using the member function autoLabelAlignment.

You may also want to disable the automatic label alignment mode because you know the size of all your pictures. In this case, call setLabelOffset.

For example, the following call will ensure that each label item will be displayed with a left margin of 30 pixels:

When a string list item is selected, it is highlighted. The IlvStringList class provides two different modes for displaying selected items:

Full selection mode When this mode (the default) is set, the selection extends on the whole width of the string list.

Partial selection mode When this mode is set, the selection extends to the item labels only.

These two modes are illustrated in the figure below:

Figure 11.22 Full Selection Mode (Left) and Partial Selection Mode (Right)

You can switch from one mode to the other using useFullSelection.

String lists can display tooltips when the mouse pointer is over partially visible items, provided that tooltips have been enabled with the member function useToolTips.


Note: Tooltips work only if the partial selection mode is set. See Choosing a Selection Mode.

String list labels can be localized.

See Localizing a Gadget.

This section covers the following topics:

There are two selection modes for string lists: single (or exclusive) selection and multiple selection.

In single selection mode, only one item can be selected at a time. This mode has two submodes:

IlvStringListSingleSelection—You can select only one item at a time.

IlvStringListSingleBrowseSelection—This mode is similar to the previous one except that clicking the selected item cancels the selection.

In multiple selection mode, several items can be selected at the same time. This mode has three submodes:

IlvStringListBrowseSelection—You can select several items at the same time either by clicking them or dragging the mouse. Similarly, you can deselect several items by clicking them or by dragging the mouse with the middle button.

IlvStringListMultipleSelection—Clicking an item selects it or cancels the selection.

IlvStringListExtendedSelection—You can extend the selection using the Shift or the Control key.

To modify the selection mode in effect, use the member function setExclusive. To change the submode, use setSelectionMode. In multiple selection mode, you can set a limit to the number of items that can be selected with the member function setSelectionLimit.

When the user double-clicks on a string list item, the Main callback is invoked. When the user selects an item or cancels the selection, the Select callback is called. To set this callback, use the member function setSelectCallback.

See Associating a Callback with a Gadget.

To control selecting and double-clicking items in a list, you can redefine the following member functions in subclasses: select (for selecting an item), unSelect (for cancelling the selection), or doIt (for double-clicking on an item).

If you want to change the selection by coding, you can use setSelected.

Items in a string list can be edited. See Finding Gadget Items.

The IlvStringList class provides an easy-to-use drag-and-drop mechanism. See Dragging and Dropping Gadget Items.