footertab pointer anim

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" >

        <RadioGroup
            android:id="@+id/main_footer"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:background="@color/c2"
            android:gravity="center_vertical"
            android:orientation="horizontal" >

            <RadioButton
                android:id="@+id/tab1"
                style="@style/main_footbar_radio"
                android:text="TAB1" />

            <ImageView
                style="@style/main_footbar_cutline"
                android:src="@drawable/widget_bar_cut_off" />

            <RadioButton
                android:id="@+id/tab2"
                style="@style/main_footbar_radio"
                android:text="TAB2" />

            <ImageView
                style="@style/main_footbar_cutline"
                android:src="@drawable/widget_bar_cut_off" />

            <RadioButton
                android:id="@+id/tab3"
                style="@style/main_footbar_radio"
                android:text="TAB3" />

            <ImageView
                style="@style/main_footbar_cutline"
                android:src="@drawable/widget_bar_cut_off" />

            <RadioButton
                android:id="@+id/tab4"
                style="@style/main_footbar_radio"
                android:text="TAB4" />
        </RadioGroup>

        <TextView
            android:id="@+id/pointer"
            android:layout_width="wrap_content"
            android:layout_height="5dp"
            android:background="#000000" 
            />
    </RelativeLayout>

</RelativeLayout>

MainActivity.java

package com.gitonway.footertab;

import android.app.Activity;
import android.graphics.Point;
import android.os.Bundle;
import android.view.Display;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.widget.TextView;

import com.nineoldandroids.animation.ObjectAnimator;

public class MainActivity extends Activity implements OnCheckedChangeListener{
	/**
	 * 指示器动画执行时间
	 */
	private final int DURATION=1 * 500;
	/**
	 * TAB项个数
	 */
	private final int TAB_NUMBER=4;
	
	private RadioGroup mRadioGroup;
	
	private TextView mTextViewPointer;
	/**
	 * 当前指示器X坐标
	 */
	private int currentX;
	/**
	 * 屏幕宽度
	 */
	private int width;
	/**
	 * 指示器宽度
	 */
	private int PointerWidth;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		init();
		
	}
	private void init() {
		
		Display display = getWindowManager().getDefaultDisplay();
		Point size = new Point();
		display.getSize(size);
		width = size.x;//屏幕宽度
		
		PointerWidth=width/TAB_NUMBER;
		mRadioGroup = (RadioGroup) findViewById(R.id.main_footer);
		mTextViewPointer=(TextView) findViewById(R.id.pointer);
		mRadioGroup.setOnCheckedChangeListener(this);
		mTextViewPointer.setWidth(PointerWidth);
		
	}
	/**
	 * 移动指针位置
	 * @param toLocation 要移动到的位置
	 * @param checkedIndex 被选中TAB索引
	 */
	private void moveTo(int toLocation,int checkedIndex)
	{
		ObjectAnimator.ofFloat(mTextViewPointer, "translationX", currentX, toLocation).setDuration(DURATION).start();
		currentX=PointerWidth*checkedIndex;
	}
	@Override
	public void onCheckedChanged(RadioGroup group, int checkedId) {
		switch (checkedId) {
		case R.id.tab1:
			moveTo(0*PointerWidth,0);
			break;
		case R.id.tab2:
			moveTo(1*PointerWidth,1);
			break;
		case R.id.tab3:
			moveTo(2*PointerWidth,2);
			break;
		case R.id.tab4:
			moveTo(3*PointerWidth,3);
			break;

		}
	}

	

}

style.xml

<style name="footbar">
        <item name="android:layout_width">fill_parent</item>
        <item name="android:layout_height">fill_parent</item>
        <item name="android:layout_weight">1</item>
        <item name="android:textSize">@dimen/text_size_10</item>
        <item name="android:singleLine">true</item>
        <item name="android:ellipsize">marquee</item>
        <item name="android:gravity">center</item>  
        <item name="android:button">@null</item>  
        <item name="android:paddingTop">@dimen/space_1</item>
        <item name="android:paddingBottom">@dimen/space_3</item>
    </style>

	
    <style name="main_footbar_radio" parent="footbar">
        <item name="android:background">@drawable/widget_bar_bg</item>
        <item name="android:padding">0dip</item>
    </style>