DragHelper 를 활용한 View Drag&Drop 애니메이션

간단한 예제 만드는법

VIewDragHelper 생성자를 통해 초기화(1.0f는 시작시 민감도라고 함)

public class DragLayout extends LinearLayout { private final ViewDragHelper mDragHelper; private View mDragView;   public DragLayout(Context context) { this(context, null); }   public DragLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); }   public DragLayout(Context context, AttributeSet attrs, int defStyle) {   super(context, attrs, defStyle); mDragHelper = ViewDragHelper.create(this, 1.0f, new DragHelperCallback()); } }

onInterceptTouchEvent 와 onTouchEvent에서 ViewDragHelper를 호출하도록 구현한다.

@Override public boolean onInterceptTouchEvent(MotionEvent ev) { final int action = MotionEventCompat.getActionMasked(ev); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { mDragHelper.cancel(); return false; } return mDragHelper.shouldInterceptTouchEvent(ev); }   @Override public boolean onTouchEvent(MotionEvent ev) { mDragHelper.processTouchEvent(ev); return true; }

DragHelperCallback 내에 clampViewPositionVertical 를 구현해보자

@Override public int clampViewPositionVertical(View child, int top, int dy) { Log.d("DragLayout", "clampViewPostionVertical "+top+","+dy); final int topBound = getPaddingTop(); final int bottomBound = getHeight() - mDragView.getHeight(); final int newTop = Math.min(Math.max(top, topBound), bottomBound); return newTop; }

이렇게 구현후 실행하면 작동하지 않을것이다.

onFinishInflate 메소드를 구현해야하며

@Override protected void onFinishInflate() { mDragView = (View) findViewById(R.id.viewHeader); }

ViewDragHelper.Callback 에서 필수 메소드인 tryCaptureView 에서 retrun값을 true를 주어야한다.

@Override public boolean tryCaptureView(View child, int pointerId) { return true; }

2차 출처 : http://flavienlaurent.com/blog/2013/08/28/each-navigation-drawer-hides-a-viewdraghelper/

1차 출처 : https://github.com/flavienlaurent/flavienlaurent.com/tree/master/viewdraghelper