本文的方法是通過addView和removeView來實作的。
一、首先讓ScrollView實作滾動監聽:
package com.willen.topFloatDemo;
import android.content.Context;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ScrollView;
/*
* ScrollView并沒有實作滾動監聽,是以我們必須自行實作對ScrollView的監聽,
* 我們很自然的想到在onTouchEvent()方法中實作對滾動Y軸進行監聽
* ScrollView的滾動Y值進行監聽
*/
public class MyScrollView extends ScrollView {
private OnScrollListener onScrollListener;
/**
* 主要是用在使用者手指離開MyScrollView,MyScrollView還在繼續滑動,我們用來儲存Y的距離,然後做比較
*/
private int lastScrollY;
public MyScrollView(Context context) {
super(context, null);
}
public MyScrollView(Context context, AttributeSet attrs) {
super(context, attrs, 0);
}
public MyScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* 設定滾動接口
* @param onScrollListener
*/
public void setOnScrollListener(OnScrollListener onScrollListener){
this.onScrollListener = onScrollListener;
}
/**
* 用于使用者手指離開MyScrollView的時候擷取MyScrollView滾動的Y距離,然後回調給onScroll方法中
*/
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
int scrollY = MyScrollView.this.getScrollY();
//此時的距離和記錄下的距離不相等,在隔5毫秒給handler發送消息
if(lastScrollY != scrollY){
lastScrollY = scrollY;
handler.sendMessageDelayed(handler.obtainMessage(), 5);
}
if(onScrollListener != null){
onScrollListener.onScroll(scrollY);
}
};
};
/**
* 重寫onTouchEvent, 當使用者的手在MyScrollView上面的時候,
* 直接将MyScrollView滑動的Y方向距離回調給onScroll方法中,當使用者擡起手的時候,
* MyScrollView可能還在滑動,是以當使用者擡起手我們隔5毫秒給handler發送消息,在handler處理
* MyScrollView滑動的距離
*/
@Override
public boolean onTouchEvent(MotionEvent ev) {
if(onScrollListener != null){
onScrollListener.onScroll(lastScrollY = this.getScrollY());
}
switch(ev.getAction()){
case MotionEvent.ACTION_UP:
handler.sendMessageDelayed(handler.obtainMessage(), 20);
break;
}
return super.onTouchEvent(ev);
}
/**
* 滾動的回調接口
*/
public interface OnScrollListener{
/**
* 回調方法, 傳回MyScrollView滑動的Y方向距離
*/
public void onScroll(int scrollY);
}
}
二、定義簡單布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<com.willen.topFloatDemo.MyScrollView
android:id="@+id/myScrollView"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<RelativeLayout
android:id="@+id/rlayout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" >
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:text="@string/text1"
android:textSize="40dp" />
</RelativeLayout>
<LinearLayout
android:id="@+id/search02"
android:layout_width="match_parent"
android:layout_height="40dip"
android:orientation="vertical" >
<EditText
android:id="@+id/search_edit"
android:layout_width="match_parent"
android:layout_height="40dip"
android:background="@drawable/bg_edittext"
android:hint="請輸入..."
android:padding="5dip"
android:singleLine="true"
android:textColorHint="#AAAAAA"
android:textSize="15dip" />
</LinearLayout>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="@string/text2"
android:textSize="40dp" />
</LinearLayout>
</com.willen.topFloatDemo.MyScrollView>
<LinearLayout
android:id="@+id/search01"
android:layout_width="match_parent"
android:layout_height="40dip"
android:orientation="vertical" >
</LinearLayout>
</RelativeLayout>
三、MainActivity
package com.willen.topFloatDemo;
import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import com.willen.topFloatDemo.MyScrollView.OnScrollListener;
public class MainActivity extends Activity implements OnScrollListener{
private EditText search_edit;
private MyScrollView myScrollView;
private int searchLayoutTop;
LinearLayout search01,search02;
RelativeLayout rlayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化控件
init();
}
private void init() {
search_edit = (EditText)findViewById(R.id.search_edit);
myScrollView = (MyScrollView)findViewById(R.id.myScrollView);
search01 = (LinearLayout)findViewById(R.id.search01);
search02 = (LinearLayout)findViewById(R.id.search02);
rlayout = (RelativeLayout)findViewById(R.id.rlayout);
myScrollView.setOnScrollListener(this);
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
if(hasFocus){
searchLayoutTop = rlayout.getBottom();//擷取searchLayout的頂部位置
}
}
//監聽滾動Y值變化,通過addView和removeView來實作懸停效果
@Override
public void onScroll(int scrollY) {
if(scrollY >= searchLayoutTop){
if (search_edit.getParent()!=search01) {
search02.removeView(search_edit);
search01.addView(search_edit);
}
}else{
if (search_edit.getParent()!=search02) {
search01.removeView(search_edit);
search02.addView(search_edit);
}
}
}
}
效果展示:向上滑動,框懸浮