拖动一个控件在另一个控件（layout)上，并固定位置在几个位置显示


实现效果： 鼠标拖动btn SSS，SSS在水平的layout上移动。 当鼠标抬起 响应UP事件。SSS会自动移动到距离其最近的Btn上，与其重合。即SSS如图只存在五个固定的显示位置。

SSS响应setOnTouchListener事件。

在MotionEvent.ACTION_UP事件中，调用TranslateAnimation动画效果，将其从UP事件位置移动到最近的btn所在位置。

即在UP事件中，响应函数：

private void setPosition() {            int positionPixel = (touchBtn.getLeft()+touchBtn.getRight())/2;            int positionIndex = (positionPixel)/btn[1].getWidth();            int toPosition = positionIndex*btn[1].getWidth()+touchBtn.getWidth()/2;                    touchBtn.layout(positionIndex*btn[1].getWidth(), touchBtn.getTop(),positionIndex*btn[1].getWidth()+touchBtn.getWidth(),                             touchBtn.getBottom());                        MoveAction = new TranslateAnimation(positionPixel - toPosition,0,0,0);            MoveAction.setDuration(500);            touchBtn.startAnimation(MoveAction);//            touchBtn.invalidate();                    }

动画效果，将其移动到最近位置上

或者也可以这样计算：

/***获得最佳停留位置*/private void setBestPosition(View v) {int width=v.getWidth();        int left = v.getLeft();        int selectedPosition = Math.round(1.0F*left/width);//四舍五入          int toPosition = selectedPosition*width;          v.layout(selectedPosition*width, v.getTop(),                  selectedPosition*width+width, v.getBottom());          TranslateAnimation animation = new TranslateAnimation(left-toPosition,0,0,0);          animation.setInterpolator(new LinearInterpolator());            animation.setDuration(400);          animation.setFillAfter(true);            v.startAnimation(animation); //        v.invalidate();    }

全代码：

public class App extends Activity{private static final String tag="App";private Context context;private FrameLayout container;private Button btn;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        context=this;                container=(FrameLayout)findViewById(R.id.container);                btn=(Button)findViewById(R.id.btn);        btn.setBackgroundResource(R.drawable.tabswitcher_short);        btn.setOnTouchListener(touchLisener);        btn.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubLog.i(tag,"btn clicked");}});    }        @Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();}OnTouchListener touchLisener=new OnTouchListener() {    int lastX, lastY;@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubswitch (event.getAction()) {case MotionEvent.ACTION_DOWN:lastX = (int) event.getRawX();                lastY = (int) event.getRawY();break;case MotionEvent.ACTION_MOVE:int dx = (int) event.getRawX() - lastX;  //int dy = (int) event.getRawY() - lastY;                  int dy = 0;                  int left = v.getLeft() + dx;                  int top = v.getTop() + dy;                  int right = v.getRight() + dx;                  int bottom = v.getBottom() + dy;                  if (left < 0) {                      left = 0;                      right = left + v.getWidth();                  }                  if (right > container.getMeasuredWidth()) {                      right = container.getMeasuredWidth();                      left = right - v.getWidth();                  }                  if (top < 0) {                      top = 0;                      bottom = top + v.getHeight();                  }                  if (bottom > container.getMeasuredHeight()) {                      bottom = container.getMeasuredHeight();                      top = bottom - v.getHeight();                  }                  v.layout(left, top, right, bottom);                  lastX = (int) event.getRawX();                  lastY = (int) event.getRawY();break;case MotionEvent.ACTION_UP:setBestPosition(v);break;default:break;}return false;}};private void setBestPosition(View v) {int width=v.getWidth();        int left = v.getLeft();        int selectedPosition = Math.round(1.0F*left/width);//四舍五入          int toPosition = selectedPosition*width;          v.layout(selectedPosition*width, v.getTop(),                  selectedPosition*width+width, v.getBottom());          TranslateAnimation animation = new TranslateAnimation(left-toPosition,0,0,0);          animation.setInterpolator(new LinearInterpolator());            animation.setDuration(400);          animation.setFillAfter(true);            v.startAnimation(animation); //        v.invalidate();    }｝

布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res/com.ql.app"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    >    <TextView android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="TEST DRAG"android:textSize="20sp"/> <FrameLayout android:id="@+id/container" android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:layout_weight="1"    >    <Button android:id="@+id/btn"    android:layout_width="80dp"android:layout_height="wrap_content"android:text="drag me!"    />    </FrameLayout>    <EditText     android:layout_width="fill_parent"    android:layout_height="wrap_content"    /></LinearLayout>

但是这样有个问题：当点击EditText弹出输入法的时候，那个拖动条会回到初始的位置，这是何故？