Class AsyncBoxView.ChildLocator

Field Detail

• lastValidOffset

  protected AsyncBoxView.ChildState lastValidOffset

  The location of the last offset calculation that is valid.

• lastAlloc

  protected Rectangle lastAlloc

  The last seen allocation (for repainting when changes are flushed upward).

• childAlloc

  protected Rectangle childAlloc

  A shape to use for the child allocation to avoid creating a lot of garbage.

Constructor Detail

• AsyncBoxView.ChildLocator

  public AsyncBoxView.ChildLocator()

  construct a child locator.

Method Detail

• childChanged

  public void childChanged(AsyncBoxView.ChildState cs)

  Notification that a child changed. This can effect whether or not new offset calculations are needed. This is called by a ChildState object that has changed it's major span. This can therefore be called by multiple threads.

• paintChildren

  public void paintChildren(Graphics g)

  Paint the children that intersect the clip area.

• getChildAllocation

  public Shape getChildAllocation(int index,
                         Shape a)

  Fetch the allocation to use for a child view. This will update the offsets for all children not yet updated before the given index.

• getViewIndexAtPoint

  public int getViewIndexAtPoint(float x,
                        float y,
                        Shape a)

  Fetches the child view index at the given point. This is called by the various View methods that need to calculate which child to forward a message to. This should be called by a block synchronized on this object, and would typically be followed with one or more calls to getChildAllocation that should also be in the synchronized block.

  Parameters:

  x - the X coordinate >= 0

  y - the Y coordinate >= 0

  a - the allocation to the View

  Returns:

  the nearest child index

• getChildAllocation

  protected Shape getChildAllocation(int index)

  Fetch the allocation to use for a child view. This does not update the offsets in the ChildState records.

• setAllocation

  protected void setAllocation(Shape a)

  Copy the currently allocated shape into the Rectangle used to store the current allocation. This would be a floating point rectangle in a Java2D-specific implmentation.

• getViewIndexAtVisualOffset

  protected int getViewIndexAtVisualOffset(float targetOffset)

  Locate the view responsible for an offset into the box along the major axis. Make sure that offsets are set on the ChildState objects up to the given target span past the desired offset.

  Returns:

  index of the view representing the given visual location (targetOffset), or -1 if no view represents that location