DragView（一）

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：
思考，自定义，使用

public class CustomViewGroup2 extends LinearLayout {    private ViewDragHelper mViewDragHelper;    public CustomViewGroup2(Context context) {        this(context,null);    }    public CustomViewGroup2(Context context, AttributeSet attrs) {        super(context, attrs);        mViewDragHelper = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {            @Override            public boolean tryCaptureView(View child, int pointerId) {                return true;            }            @Override            public int clampViewPositionHorizontal(View child, int left, int dx) {              final  int leftBound = getPaddingLeft();                final int rightBound = getWidth()-child.getWidth()-leftBound;                final int mewLeft = Math.min(Math.max(left,leftBound),rightBound);                return mewLeft;            }            @Override            public int clampViewPositionVertical(View child, int top, int dy) {                return top;            }        });    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        return mViewDragHelper.shouldInterceptTouchEvent(ev);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        mViewDragHelper.processTouchEvent(event);        return true;    }}

调用

<?xml version="1.0" encoding="utf-8"?><com.example.administrator.testapplication.CustomViewGroup2 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 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 can be dragged !"        android:layout_width="100dp"        android:layout_height="100dp"/></com.example.administrator.testapplication.CustomViewGroup2>

部分方法解释

  /**         * Restrict the motion of the dragged child view along the horizontal axis.         * The default implementation does not allow horizontal motion; the extending         * class must override this method and provide the desired clamping.         *         *         * @param child Child view being dragged         * @param left Attempted motion along the X axis         * @param dx Proposed change in position for left         * @return The new clamped position for left         */        public int clampViewPositionHorizontal(View child, int left, int dx) {            return 0;        }  /**         * Restrict the motion of the dragged child view along the vertical axis.         * The default implementation does not allow vertical motion; the extending         * class must override this method and provide the desired clamping.         *         *         * @param child Child view being dragged         * @param top Attempted motion along the Y axis         * @param dy Proposed change in position for top         * @return The new clamped position for top         */        public int clampViewPositionVertical(View child, int top, int dy) {            return 0;        }

效果：