Android Open Source - adventure.datetime Input Handler

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License

The source code is released under:

MIT License

Java Source Code

package ca.cmput301f13t03.adventure_datetime.view.treeView;
//  w  w  w  .  ja v a2 s  . c  o m
import android.view.MotionEvent;
import ca.cmput301f13t03.adventure_datetime.view.IFragmentSelected;

class InputHandler 
{
  private Camera m_camera = null;
  private NodeGrid m_nodeGrid = null;
  
  // touch input
  private boolean m_hasPrimaryTouch = false;
  private int m_pointerId = 0; // only supporting single touch
  private boolean m_isDragging = false;
  
  private static final float DRAG_MINIMUM_SQUARED = 625.0f;
  private float m_initialX = 0;
  private float m_initialY = 0;
  private float m_previousX = 0;
  private float m_previousY = 0;
  
  private IFragmentSelected m_selectionCallback = null;
  
  private enum MoveType
  {
    TAP,
    DRAG
  }
  
  public InputHandler(Camera camera, NodeGrid nodeGrid)
  {
    m_camera = camera;
    m_nodeGrid = nodeGrid;
  }
  
  public boolean OnTouchAction(MotionEvent event)
  {
    boolean result = false;
    int pointerIndex = event.getActionIndex();
    int pointerId = event.getPointerId(pointerIndex);
    
    if(event.getActionMasked() == MotionEvent.ACTION_DOWN)
    {
      HandleTouchDown(event, pointerId, pointerIndex);
    }
    else if(event.getActionMasked() == MotionEvent.ACTION_UP)
    {
      result = HandleTouchUp(event, pointerId, pointerIndex);
    }
    else if(event.getActionMasked() == MotionEvent.ACTION_MOVE)
    {
      result = HandleMove(event, pointerId, pointerIndex);
    }
    else if(event.getActionMasked() == MotionEvent.ACTION_CANCEL)
    {
      result = HandleCancel(event, pointerId);
    }
    
    return result;
  }
  
  public void SetSelectionCallback(IFragmentSelected callback)
  {
    m_selectionCallback = callback;
  }
  
  public IFragmentSelected GetSelectionCallback()
  {
    return m_selectionCallback;
  }
  
  private boolean HandleTouchUp(MotionEvent event, int pointerId, int pointerIndex)
  {
    boolean result = false;
    
    if(m_hasPrimaryTouch && m_pointerId == pointerId)
    {
      // then the pointer was released
      // stop tracking
      m_pointerId = 0;
      m_hasPrimaryTouch = false;
      result = true;
      
      m_previousX = event.getX(pointerIndex);
      m_previousY = event.getY(pointerIndex);
      
      // and check for a tap event
      if(this.GetMoveType(m_previousX, m_previousY) == MoveType.TAP)
      {
        HandleTap(m_previousX, m_previousY);
      }
    }
    else
    {
      // some other pointer was released, don't care
      result = false;
    }
    
    return result;
  }
  
  private boolean HandleTouchDown(MotionEvent event, int pointerId, int pointerIndex)
  {
    boolean result = false;
    
    if(!m_hasPrimaryTouch)
    {
      m_pointerId = pointerId;
      m_previousX = event.getX(pointerIndex);
      m_previousY = event.getY(pointerIndex);
      m_initialX = m_previousX;
      m_initialY = m_previousY;
      m_hasPrimaryTouch = true;
      m_isDragging = false;
      
      result = true;
    }
    else
    {
      // reject input if we are already tracking a pointer
      result = false;
    }
    
    return result;
  }
  
  private boolean HandleMove(MotionEvent event, int pointerId, int pointerIndex)
  {
    boolean result = false;
    
    if(m_hasPrimaryTouch && m_pointerId == pointerId)
    {
      // only handle the move if it is the primary touch index
      result = true;
      
      float newX = event.getX(pointerIndex);
      float newY = event.getY(pointerIndex);
      
      // determine move type (tap or drag)
      MoveType type = GetMoveType(newX, newY);
      
      // perform action
      if(type == MoveType.DRAG)
      {
        HandleDrag(newX, newY);
      }
      // ignoring tap until the tap is released
      
      m_previousX = newX;
      m_previousY = newY;
    }
    
    return result;
  }
  
  private boolean HandleCancel(MotionEvent event, int pointerId)
  {
    boolean result = false;
    
    if(m_hasPrimaryTouch && m_pointerId == pointerId)
    {
      m_hasPrimaryTouch = false;
      m_pointerId = 0;
      result = true;
    }
    else
    {
      // reject input if we are already tracking a pointer
      result = false;
    }
    
    return result;
  }
  
  private void HandleDrag(float currX, float currY)
  {
    m_isDragging = true;
    
    float deltaX = currX - m_previousX;
    float deltaY = currY - m_previousY;
    
    float newX = m_camera.GetXTarget() - deltaX;
    float newY = m_camera.GetYTarget() - deltaY;
    
    m_camera.LookAt(newX, newY);
  }
  
  private void HandleTap(float currX, float currY)
  {
    // early out if we are dragging
    if(m_isDragging)
    {
      return;
    }
    
    float cords[] = { currX, currY };
    m_camera.ScreenCordsToWorldCords(cords);
    
    FragmentNode tappedNode = m_nodeGrid.GetNodeAtLocation((int)(cords[0]), (int)(cords[1]));
    
    if(tappedNode != null)
    {
      // the node was selected!
      if(m_selectionCallback != null)
      {
        m_selectionCallback.OnFragmentSelected(tappedNode.GetFragment());
      }
      // else... I guess no one will ever know...
    }
    // else we just ignore the tap, cuz there is nothing there!
  }
  
  private MoveType GetMoveType(float currX, float currY)
  {
    if(GetDistanceFromStartSquared(currX, currY) > DRAG_MINIMUM_SQUARED)
    {
      return MoveType.DRAG;
    }
    else
    {
      return MoveType.TAP;
    }
  }
  
  private float GetDistanceFromStartSquared(float currX, float currY)
  {
    return   (currX - m_initialX)*(currX - m_initialX) +
        (currY - m_initialY)*(currY - m_initialY);
  }
}

Java Source Code List

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