Design Specifications and Guidelines - Working with OLE Embedded and Linked Objects

Activating Objects

Although selecting an object provides access to commands applicable to the object as a whole, it does not enable editing the content of the object. The object must be activated in order to provide user interaction with the internal content of the object. There are two basic models for activating objects: outside-in activation and inside-out activation.

Outside-in Activation

Outside-in activation requires that the user choose an explicit activation command. Clicking, or some other selection operation, performed on an object that is already selected simply reselects that object and does not constitute an explicit action. The user activates the object by using a particular command such as Edit or Play, usually the object's default command. Shortcut actions that correspond to these commands, such as double-clicking or pressing a shortcut key, can also activate the object. Most container applications use this model because it allows the user to easily select objects and reduces the risk of inadvertently activating an object whose underlying code may take a significant amount of time to load and dismiss.

When supporting outside-in activation, display the standard pointer (northwest arrow) over an outside-in activated object within your container when the object is selected but inactive. This indicates to the user that the outside-in object behaves as a single, opaque object. When the user activates the object, the object's application displays the appropriate pointer for its content. Use the registry to determine the object's activation command.

Inside-out Activation

With inside-out activation, interaction with an object is direct; that is, the object is activated as the user moves the pointer over the extent of the object. From the user's perspective, inside-out objects are indistinguishable from native data because the content of the object is directly interactive and no additional action is necessary. Use this method for the design of objects that benefit from direct interaction, or when activating the object has little effect on performance or use of system resources.

Inside-out activation requires closer cooperation between the container and the object. For example, when the user begins a selection within an inside-out object, the container must clear its own selection so that the behavior is consistent with normal selection interaction. An object supporting inside-out activation controls the appearance of the pointer as it moves over its extent and responds immediately to input. Therefore, to select the object as a whole, the user selects the border, or some other handle, provided by the object or its container. For example, the container application can support selection techniques, such as region selection, that select the object.

Container Control of Activation

The container application determines how to activate its component objects: either it allows the inside-out objects to handle events directly or it intercedes and activates them only upon an explicit action. This is true regardless of the capability or preference setting of the object. That is, even though an object may register inside-out activation, it can be treated by a particular container as outside-in. Use an activation style for your container that is most appropriate for its specific use and in keeping with its own native style of activation so that objects can easily be assimilated.

Regardless of the activation capability of the object, a container should always activate its content objects of the same type consistently. Otherwise, the unpredictability of the interface is likely to impair its usability.

Fundamentals of Designing User Interaction

Windows Interface Components

Design Specifications and Guidelines

Appendixes and References