When an object is added to a manager, you
can specify the index of the layer where it should be inserted.
The following method adds the specified
graphic object to the specified layer:
void addObject(IlvGraphic obj, int layer, boolean redraw)
To retrieve the index of the layer that
contains a certain graphic object, use the following method:
int getLayer(IlvGraphic obj)
To change the layer, use the following
method:
void setLayer(IlvGraphic obj, int newLayer, boolean redraw)
There are two essential properties that you
can specify for the objects within a layer: visibility and
scalability.
Visibility
With the following methods, you can
indicate whether the objects within a certain layer should be
visible to the user:
void setVisible(int layer, boolean value, boolean redraw)
boolean isVisible(int layer)
You can also decide whether a layer is
visible or not within a particular view. Refer to the following
methods:
void setVisible(IlvManagerView view, int layer, boolean set, boolean redraw)
boolean isVisible(IlvManagerView view, int layer)
Finally, you can have a visible layer in a view temporarily hide
itself depending on certain conditions, generally depending on
the zoom factor. This can be achieved through an IlvLayerVisibilityFilter that is called
each time the
IlvManager
needs to redraw a layer. You should implement this interface and
return whether or not the layer is visible with the
isVisible
method. To be active, this filter must be registered on the
corresponding IlvManagerLayer using the addVisibilityFilter method.
Selectability
You can specify whether objects within a
layer can be selected or not using the following methods. Objects
that cannot be selected cannot be modified:
boolean isSelectable(int layer)
void setSelectable(int layer, boolean v)
For more methods dealing with layers, see the class IlvManager in the reference documentation.