Class ViewportAutoexposeHelper

java.lang.Object
org.eclipse.gef.editparts.ViewportAutoexposeHelper
All Implemented Interfaces:
AutoexposeHelper

public class ViewportAutoexposeHelper extends 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.).
  • Field Details

  • Constructor Details

    • 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, org.eclipse.draw2d.geometry.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 Details

    • detect

      public boolean detect(org.eclipse.draw2d.geometry.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:
    • step

      public boolean step(org.eclipse.draw2d.geometry.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:
    • toString

      public String toString()
      Overrides:
      toString in class Object
      See Also:
    • findViewport

      protected org.eclipse.draw2d.Viewport findViewport(GraphicalEditPart part)