DragView（二）

传承者（Inheritors）打造共同进步生态圈！！！
转载：
http://blog.csdn.net/lmj623565791/article/details/46858663

三段论：声明属性，自定义view，调用

public class CustomViewGroup3 extends LinearLayout {   private ViewDragHelper mViewDragHelper;    private View mDragView,mAutoBackView,mEdgeTrackerView;    private Point mAutoBackOriginPos = new Point();    public CustomViewGroup3(Context context) {        this(context,null);    }    public CustomViewGroup3(Context context, AttributeSet attrs) {        super(context, attrs);        mViewDragHelper = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {            @Override            public boolean tryCaptureView(View child, int pointerId) {               //mEdgeTrakerView禁止直接移动                return child == mDragView || child == mAutoBackView;            }            @Override            public int clampViewPositionVertical(View child, int top, int dy) {                return top;            }            @Override            public int clampViewPositionHorizontal(View child, int left, int dx) {                return left;            }            //当View被释放的时候调用            @Override            public void onViewReleased(View releasedChild, float xvel, float yvel) {                //手释放view自动回去                if(releasedChild == mAutoBackView){                    mViewDragHelper.settleCapturedViewAt(mAutoBackOriginPos.x, mAutoBackOriginPos.y);                    invalidate();                }            }            //边界拖动时回调            @Override            public void onEdgeDragStarted(int edgeFlags, int pointerId) {                mViewDragHelper.captureChildView(mEdgeTrackerView,pointerId);            }        });        mViewDragHelper.setEdgeTrackingEnabled(ViewDragHelper.EDGE_ALL);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        return mViewDragHelper.shouldInterceptTouchEvent(ev);    }    @Override    public boolean onTouchEvent(MotionEvent event) {      mViewDragHelper.processTouchEvent(event);        return true;    }    @Override    public void computeScroll() {//        super.computeScroll();        if(mViewDragHelper.continueSettling(true)){            invalidate();        }    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        super.onLayout(changed, l, t, r, b);        mAutoBackOriginPos.x = mAutoBackView.getLeft();        mAutoBackOriginPos.y = mAutoBackView.getTop();    }    @Override    protected void onFinishInflate() {        super.onFinishInflate();    mDragView =getChildAt(0);        mAutoBackView = getChildAt(1);        mEdgeTrackerView = getChildAt(2);    }}

调用

<com.example.administrator.testapplication.CustomViewGroup3 xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:layout_margin="10dp"        android:gravity="center"        android:layout_gravity="center"        android:background="#44ff0000"        android:text="I can be dragged !"        android:layout_width="100dp"        android:layout_height="100dp"/>    <TextView        android:layout_margin="10dp"        android:layout_gravity="center"        android:gravity="center"        android:background="#44ff0000"        android:text="I  will back !"        android:layout_width="100dp"        android:layout_height="100dp"/>    <TextView        android:layout_margin="10dp"        android:layout_gravity="center"        android:gravity="center"        android:background="#44ff0000"        android:text="use edge tracker me !"        android:layout_width="100dp"        android:layout_height="100dp"/></com.example.administrator.testapplication.CustomViewGroup3>

效果：