org.eclipse.gef.editparts
Class ViewportAutoexposeHelper

java.lang.Object
  org.eclipse.gef.editparts.ViewportAutoexposeHelper

All Implemented Interfaces:

AutoexposeHelper

public class ViewportAutoexposeHelper
extends java.lang.Object
implements AutoexposeHelper

An implementation of AutoexposeHelper that performs autoscrolling of a Viewport figure. This helper is for use with graphical editparts that contain a viewport figure. This helper will search the editpart and find the viewport. Autoscroll will occur when the detect location is inside the viewport's bounds, but near its edge. It will continue for as long as the location continues to meet these criteria. The autoscroll direction is approximated to the nearest orthogonal or diagonal direction (north, northeast, east, etc.).

Nested Class Summary

Nested classes/interfaces inherited from interface org.eclipse.gef.AutoexposeHelper

AutoexposeHelper.Search

Field Summary

protected GraphicalEditPart

owner

Constructor Summary

ViewportAutoexposeHelper(GraphicalEditPart owner)
Constructs a new helper on the given GraphicalEditPart.

ViewportAutoexposeHelper(GraphicalEditPart owner, Insets threshold)
Constructs a new helper on the given GraphicalEditPart.

Method Summary

boolean	detect(Point where) Returns true if the given point is inside the viewport, but near its edge.
protected Viewport	findViewport(GraphicalEditPart part)
boolean	step(Point where) Returns true if the given point is outside the viewport or near its edge.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

owner

protected GraphicalEditPart owner

Constructor Detail

ViewportAutoexposeHelper

public ViewportAutoexposeHelper(GraphicalEditPart owner)

Constructs a new helper on the given GraphicalEditPart. The editpart must have a Viewport somewhere between its contentsPane and its figure inclusively.

Parameters:

owner - the GraphicalEditPart that owns the Viewport

ViewportAutoexposeHelper

public ViewportAutoexposeHelper(GraphicalEditPart owner,
                                Insets threshold)

Constructs a new helper on the given GraphicalEditPart. The editpart must have a Viewport somewhere between its contentsPane and its figure inclusively.

Parameters:

owner - the GraphicalEditPart that owns the Viewport

threshold - the Expose Threshold to use when determing whether or not a scroll should occur.

Method Detail

detect

public boolean detect(Point where)

Returns true if the given point is inside the viewport, but near its edge.

Specified by:

detect in interface AutoexposeHelper

Parameters:

where - the mouse's current location in the viewer

Returns:

true if the location is interesting

See Also:

AutoexposeHelper.detect(org.eclipse.draw2d.geometry.Point)

step

public boolean step(Point where)

Returns true if the given point is outside the viewport or near its edge. Scrolls the viewport by a calculated (time based) amount in the current direction. todo: investigate if we should allow auto expose when the pointer is outside the viewport

Specified by:

step in interface AutoexposeHelper

Parameters:

where - the current location of the mouse in the viewer

Returns:

a hint indicating whether this helper should continue to be invoked

See Also:

AutoexposeHelper.step(org.eclipse.draw2d.geometry.Point)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()

findViewport

protected Viewport findViewport(GraphicalEditPart part)