This section explains how to manipulate the objects contained in a manager. It is divided as follows:

The IlvManager class has been designed to handle a large number of graphic objects. In order to perform graphical operations efficiently (for example, redrawing part of a view, locating the objects at a given position, and so on), the manager uses a complex internal data structure where graphic objects are organized according to their geometry, that is, their bounding box. To keep this data structure up to date, the manager needs to be aware of any modification in the geometry of its graphic objects. This is why any such modification should be carried out in the following manner:

The easiest way to do this is to use the dedicated IlvManager member functions respecting these requirements:

For simple geometric operations such as moving, translating, or reshaping, IlvManager provides the following member functions that do not need to call IlvManager::applyToObject:

The following code gets a pointer to an object named test from the manager. If this object exists, it is translated 10 pixels right and 20 pixels down, and then redrawn (fourth parameter set to IlTrue):

In order to apply a user-defined function to objects that are located either partly or wholly within a specific region, use the following IlvManager member functions:

Use the following two member functions of IlvManager to handle the selection state of objects:

The following code gets a pointer to an object named test from the manager. If this object exists, it is selected (second parameter is set to IlTrue) and redrawn (third parameter set to IlTrue):

The IlvManager member functions involved in selection tasks are the following:

This example shows how to attach new selection handle objects to line objects:

The following code changes the function called to create the selection object. If the selected object is an IlvLine or an instance of a class derived from it, the manager uses the IlvLineHandle object to draw the selection:

Selecting is a basic process for managers and most manager functions should apply to a selected list of objects. A manager selection can be thought of as a special set holding some of the managed objects. To display selected objects within a manager,  Views creates selection objects that are stored in the manager. The difference between these objects and others is that they are internally managed and cannot be manipulated.

The following example shows an accelerator that translates all selected objects ten pixels right and 20 pixels down. This accelerator uses the IlvManager::applyToSelections member function to translate each of the objects. Redrawing of the objects is done once at the end of the call to this method, as is done for all the apply functions, because its third parameter is set to the default value IlTrue.

Several member functions of the IlvManager class describe properties that are assigned to an object when it is added to a manager (for example, IlvManager::isSelectable, IlvManager::setSelectable, IlvManager::isResizeable, and so on).

You can also add specific properties to each object by means of the property-related member functions of the IlvGraphic class. These properties are application-dependent and have no effect on the manager.

IlvManager provides member functions to check whether an object has a property or to change a property of an object.

This is an example of how to set an object in a manager as unmovable:

The IlvManager class provides member functions to help organize the layout of graphic objects.

The IlvManager::group member function lets you create an IlvGraphicSet from an array of objects and put the objects from an IlvGraphicSet into the manager.

The IlvManager::unGroup member function lets you do the inverse of this.

This is an example of an accelerator that groups selected objects:

The first line checks the number of objects and returns if no objects are selected. Then, a pointer to the selected objects is obtained using the IlvManager::getSelections member function. The next line creates the group. The new object is selected at the end of this accelerator.

Some IlvManager member functions are defined to automatically align objects with respect to each other:

Another member function duplicates objects, that is, it creates a copy of the objects and inserts them into the manager:

This accelerator gives the width of the first selected object to all the selected objects:

The value IlTrue passed to IlvManager::sameWidth indicates that the objects are automatically redrawn.