Package edu.cnu.mdi.graphics.toolbar

Class GestureContext

java.lang.Object
edu.cnu.mdi.graphics.toolbar.GestureContext
public final class GestureContext extends Object
Encapsulates the state of a single user interaction ("gesture") on a canvas.

A gesture typically begins on a mouse press (or the first meaningful move for hover-driven tools), proceeds through zero or more updates, and ends on release or exit. This class packages:

  • The owning AToolBar
  • The canvas Component
  • The press-time target object (may be null)
  • The press point (immutable)
  • The previous and current points (updated as events arrive)
  • Modifier key state (shift/ctrl/alt/meta) as of the most recent update

Immutability and copies

The press-time values are immutable, and this class returns defensive copies for all Point accessors to avoid accidental external mutation.

  • Constructor Details

    • GestureContext

      public GestureContext(AToolBar toolBar, Component canvas, Object target, Point pressPoint, MouseEvent e)
      Create a context at gesture start using a mouse event.
      Parameters:
      toolBar - owning toolbar (non-null)
      canvas - canvas component (non-null)
      target - press-time target (may be null)
      pressPoint - press point (non-null)
      e - initiating mouse event (may be null)

  • Method Details

    • getRubberbandAngleDeg

      public Double getRubberbandAngleDeg()
      Optional extra angle for rubberband tools (e.g. RADARC) in degrees.

      For RADARC this is the signed, unwrapped sweep (can exceed 180 in magnitude).

      Returns:
      the angle in degrees, or null if not provided

    • update

      public void update(MouseEvent e)
      Update the context using the event's point and modifier keys.
      Parameters:
      e - mouse event (non-null)

    • update

      public void update(Point current, MouseEvent e)
      Update the context using an explicit point and an event for modifier keys.
      Parameters:
      current - new current point (non-null)
      e - mouse event used to update modifiers (may be null)

    • getSourceEvent

      public MouseEvent getSourceEvent()
      Returns:
      source mouse event (may be null)

    • getRecentEvent

      public MouseEvent getRecentEvent()
      Returns:
      most recent mouse event (may be null)

    • getToolBar

      public AToolBar getToolBar()
      Returns:
      owning toolbar (never null)

    • getCanvas

      public Component getCanvas()
      Returns:
      canvas component (never null)

    • getTarget

      public Object getTarget()
      Returns:
      press-time target object (may be null)

    • getPressPoint

      public Point getPressPoint()
      Returns:
      copy of the press point

    • getPreviousPoint

      public Point getPreviousPoint()
      Returns:
      copy of the previous point

    • getCurrentPoint

      public Point getCurrentPoint()
      Returns:
      copy of the current point

    • deltaX

      public int deltaX()
      Returns:
      incremental delta x (current - previous)

    • deltaY

      public int deltaY()
      Returns:
      incremental delta y (current - previous)

    • totalDeltaX

      public int totalDeltaX()
      Returns:
      total delta x (current - press)

    • totalDeltaY

      public int totalDeltaY()
      Returns:
      total delta y (current - press)

    • isShiftDown

      public boolean isShiftDown()
      Returns:
      true if shift is down at last update

    • isControlDown

      public boolean isControlDown()
      Returns:
      true if control is down at last update

    • isAltDown

      public boolean isAltDown()
      Returns:
      true if alt is down at last update

    • isMetaDown

      public boolean isMetaDown()
      Returns:
      true if meta/command is down at last update