/**
 * 可拖拽的父容器Layout，只需要將內容圖片在xml佈局檔案中設定在父容器內即可
 * 1.主要利用ViewDragHelper這個類來實現拖拽
 * Created by CaiXi on 2016/8/23.
 */
public class DragLayout extends RelativeLayout{
    private ViewDragHelper mDragger;
    public DragLayout(Context context) {
        this(context, null);
}

    public DragLayout(Context context, 
 
AttributeSet attrs) {
        this(context, attrs, 0);
}

    public DragLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
mDragger = 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 
 
newLeft = Math.min(Math.max(left, leftBound), rightBound);
                return newLeft;
}

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

            @Override
public int getViewHorizontalDragRange(View child) {
                return getMeasuredWidth() - child.getMeasuredWidth();
}

            @Override
public int getViewVerticalDragRange(View child) {
                return getMeasuredHeight() - child.getMeasuredHeight();
}

            @Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
                moveToSide(releasedChild);
invalidate();
}
        });
}

    private void moveToSide(View view) {
        float top = view.getTop();
        float bottom = getMeasuredHeight() - view.getBottom();
        float right = getMeasuredWidth() - view.getRight();
        float left = view.getLeft();
//上下滑動
if ((top < bottom ? top : bottom) / getMeasuredHeight() < (right < left ? right : left) / getMeasuredWidth()) {
            mDragger.settleCapturedViewAt(view.getLeft(), top < bottom ? 0 : getMeasuredHeight() - view.getMeasuredHeight());
} else {
            //左右滑動
mDragger.settleCapturedViewAt(left < right ? 0 : getMeasuredWidth() - view.getMeasuredWidth(), view.getTop());
}
    }

    @Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
        return mDragger.shouldInterceptTouchEvent(ev);
}

    @Override
public boolean onTouchEvent(MotionEvent event) {
        mDragger.processTouchEvent(event);
        return false;
}

    @Override
public void computeScroll() {
        if (mDragger.continueSettling(true)) {
            invalidate();
}
    }

    @Override
protected void onFinishInflate() {
        super.onFinishInflate();
        for (int i = 0; i < getChildCount(); i++) {
            getChildAt(i).setClickable(true);
}
    }
}

根佈局必須為framelayout 才能實現隨意拖動效果