ScrollView中浮动条的实现

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简单的浮窗
http://www.open-open.com/lib/view/open1467185415741.html

ScrollView中如果内容比较长，往下拉的时候有一部分（通常是菜单）View就一直固定在屏幕顶端，像个浮动条一样，该效果Web页面使用比较多。
实现这种效果需要重写ScrollView的onScrollChanged(),具体如下：

import android.content.Context;import android.util.AttributeSet;import android.view.View;import android.widget.ScrollView;/** * 带浮动条的ScrollView *  *  */public class ObservableScrollView extends ScrollView {private OnScrollListener onScrollListener = null;private View viewInScroll,viewOutScroll;public ObservableScrollView(Context context, AttributeSet attrs,int defStyle) {super(context, attrs, defStyle);}public ObservableScrollView(Context context, AttributeSet attrs) {super(context, attrs);}public ObservableScrollView(Context context) {super(context);}public void setOnScrollListener(OnScrollListener onScrollListener) {this.onScrollListener = onScrollListener;}@Overrideprotected void onScrollChanged(int x, int y, int oldx, int oldy) {super.onScrollChanged(x, y, oldx, oldy);if (onScrollListener != null) {onScrollListener.onScrollChanged(this, x, y, oldx, oldy);}computeFloatIfNecessary();}/** * 监听ScrollView滚动接口 * @author reyo * */public interface OnScrollListener {public void onScrollChanged(ObservableScrollView scrollView, int x,int y, int oldx, int oldy);}/** * 设置需要浮动的View * @param viewInScroll ScollView内的view * @param viewFloat ScollView外的view，真正需要浮动的view */public void setFloatView(View viewInScroll,View viewOutScroll){this.viewInScroll=viewInScroll;this.viewOutScroll=viewOutScroll;}private void computeFloatIfNecessary(){if(viewInScroll==null&&viewOutScroll==null){return;}// 获取ScrollView的x,y坐标int[] location = new int[2];this.getLocationInWindow(location);// 获取浮动View的x,y坐标int[] loc = new int[2];viewInScroll.getLocationOnScreen(loc);// 当浮动view的y <= ScrollView的y坐标时，把固定的view显示出来if (loc[1] <= location[1]) {// 处理一下把原有view设置INVISIBLE，这样显示效果会好点viewOutScroll.setVisibility(View.VISIBLE);viewInScroll.setVisibility(View.INVISIBLE);} else {// 记得还原回来viewOutScroll.setVisibility(View.GONE);viewInScroll.setVisibility(View.VISIBLE);}}}

用法：

import android.app.Activity;import android.os.Bundle;import android.util.Log;import com.reyo.view.ObservableScrollView;public class FloatActivity extends Activity{private ObservableScrollView scrollView;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_float);scrollView = (ObservableScrollView) findViewById(R.id.scrollView);scrollView.setFloatView(findViewById(R.id.viewInScroll), findViewById(R.id.viewOutScroll));scrollView.setOnScrollListener(new com.reyo.view.ObservableScrollView.OnScrollListener() {@Overridepublic void onScrollChanged(ObservableScrollView scrollView, int x,int y, int oldx, int oldy) {Log.i("tag", "y="+y+";oldy="+oldy);}});}}

界面：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <com.reyo.view.ObservableScrollView        android:id="@+id/scrollView"        android:layout_width="match_parent"        android:layout_height="match_parent" >        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"             android:orientation="vertical"            >            <ImageView                android:id="@+id/img"                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:src="@drawable/pic" />            <LinearLayout                android:id="@+id/viewInScroll"                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal" >                <Button                    android:id="@+id/button0"                    android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:text="排队叫号" />                <Button                    android:id="@+id/button1"                    android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:text="预定桌位" />            </LinearLayout>            <TextView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:layout_marginTop="20dp"                android:padding="5dp"                android:text="@string/test1"                android:textColor="#555555"                android:textSize="20dip" />            <TextView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:layout_marginTop="20dp"                android:padding="5dp"                android:text="@string/test2"                android:textColor="#555555"                android:textSize="20dip" />            <TextView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:layout_marginTop="20dp"                android:padding="5dp"                android:text="@string/test3"                android:textColor="#555555"                android:textSize="20dip" />            <TextView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:layout_marginTop="20dp"                android:padding="5dp"                android:text="@string/test4"                android:textColor="#555555"                android:textSize="20dip" />        </LinearLayout>    </com.reyo.view.ObservableScrollView>    <FrameLayout        android:id="@+id/viewOutScroll"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentTop="true"        android:visibility="gone" >        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:orientation="horizontal" >            <Button                android:id="@+id/button0"                android:layout_width="0dp"                android:layout_height="wrap_content"                android:layout_weight="1"                android:text="排队叫号" />            <Button                android:id="@+id/button1"                android:layout_width="0dp"                android:layout_height="wrap_content"                android:layout_weight="1"                android:text="预定桌位" />        </LinearLayout>    </FrameLayout></RelativeLayout>

测试时尽量让ScrollView超过一屏，好让其滑动，这样才能看出效果。

Android 仿美团网,大众点评购买框悬浮效果之修改版
http://blog.csdn.net/xiaanming/article/details/17761431

一个可以滚动监听的类，这下可以根据自己的需求任意扩展了

import android.content.Context;import android.util.AttributeSet;import android.view.MotionEvent;import android.widget.ScrollView;/** * A custom ScrollView that can accept a scroll listener. */public class ObservableScrollView extends ScrollView {    private Callbacks mCallbacks;    public ObservableScrollView(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    protected void onScrollChanged(int l, int t, int oldl, int oldt) {        super.onScrollChanged(l, t, oldl, oldt);        if (mCallbacks != null) {            mCallbacks.onScrollChanged(t);        }    }    @Override    public boolean onTouchEvent(MotionEvent ev) {        if (mCallbacks != null) {            switch (ev.getActionMasked()) {                case MotionEvent.ACTION_DOWN:                    mCallbacks.onDownMotionEvent();                    break;                case MotionEvent.ACTION_UP:                case MotionEvent.ACTION_CANCEL:                    mCallbacks.onUpOrCancelMotionEvent();                    break;            }        }        return super.onTouchEvent(ev);    }    @Override    public int computeVerticalScrollRange() {        return super.computeVerticalScrollRange();    }    public void setCallbacks(Callbacks listener) {        mCallbacks = listener;    }    public static interface Callbacks {        public void onScrollChanged(int scrollY);        public void onDownMotionEvent();        public void onUpOrCancelMotionEvent();    }}

如何解决ViewPager在ScrollView中滑动经常失效、无法正常滑动问题？
解决方法只需要在接近水平滚动时ScrollView不处理事件而交由其子View(即这里的ViewPager)处理即可，重写ScrollView的onInterceptTouchEvent函数，如下：

package cc.newnews.view;import android.content.Context;import android.util.AttributeSet;import android.view.GestureDetector;import android.view.GestureDetector.SimpleOnGestureListener;import android.view.MotionEvent;import android.widget.ScrollView;public class VerticalScrollView extends ScrollView {private GestureDetector mGestureDetector;public VerticalScrollView(Context context, AttributeSet attrs) {super(context, attrs);mGestureDetector = new GestureDetector(context, new YScrollDetector());}@Overridepublic boolean onInterceptTouchEvent(MotionEvent ev) {return super.onInterceptTouchEvent(ev)&& mGestureDetector.onTouchEvent(ev);}class YScrollDetector extends SimpleOnGestureListener {@Overridepublic boolean onScroll(MotionEvent e1, MotionEvent e2,float distanceX, float distanceY) {/** * 如果我们滚动更接近水平方向,返回false,让子视图来处理它 */return (Math.abs(distanceY) > Math.abs(distanceX));}}}

再将xml中的ScrollView改为<xxx.xxx.xxx.VerticalScrollView>即包名.重写的ScrollView的类名)即可。
本方法同样适用于ScrollView中ListView等其他View无法滚动。

Android UI开发第四十篇——ScrollTricks介绍
http://blog.csdn.net/xyz_lmn/article/details/20557925

Android-ObservableScrollView
https://github.com/ksoichiro/Android-ObservableScrollView

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