package com.android.buttonpageflipper;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;
import android.widget.ImageView;
import android.widget.ViewFlipper;

/**
 * Android實現帶漸顯按鈕的左右滑動效果
 * @Description: 自然狀態下按鈕不可見，觸摸屏幕時顯示按鈕

 *
 * @Author Hanyonglu
 *
 */
public class MainActivity extends Activity {
    //聲明兩個按鈕，分別代表向左和向右滑動
    private ImageView btnLeft=null;
    private ImageView btnRight=null;
    
    //設置WindowManager
    private WindowManager wm=null;
    private WindowManager.LayoutParams wmParams=null;
    
    //ImageView的alpha值   
    private int mAlpha = 0;
    private boolean isHide;
    
    private ViewFlipper viewFlipper = null;
    
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        setTitle("Android實現漸顯按鈕的左右滑動效果");
        viewFlipper = (ViewFlipper) this.findViewById(R.id.myViewFlipper);
        
        //初始化左右按鈕
        initImageButtonView();
    }
    
    /**
     * 初始化懸浮按鈕
     */
    private void initImageButtonView(){
        //獲取WindowManager
        wm=(WindowManager)getApplicationContext().getSystemService("window");
        
        //設置LayoutParams相關參數
        wmParams = new WindowManager.LayoutParams();
        
        //設置window type
        wmParams.type=LayoutParams.TYPE_PHONE;   
        
        //設置圖片格式，效果為背景透明
        wmParams.format=PixelFormat.RGBA_8888;   
        
        //設置Window flag參數
         wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL 
                               | LayoutParams.FLAG_NOT_FOCUSABLE;

        //設置x、y初始值
        wmParams.x=0;
        wmParams.y=0;
        
        //設置窗口長寬數據
        wmParams.width=50;
        wmParams.height=50;
        
        //創建左右按鈕
        createLeftButtonView();
        createRightButtonView();
    }
    
    /**
     * 設置左邊按鈕
     */
    private void createLeftButtonView(){
        btnLeft=new ImageView(this);
        btnLeft.setImageResource(R.drawable.left);
        btnLeft.setAlpha(0);
        
        btnLeft.setOnClickListener(new View.OnClickListener() {    
            public void onClick(View arg0) {
                //上一個圖像
                viewFlipper.setInAnimation(MainActivity.this, R.anim.push_left_in);
                viewFlipper.setOutAnimation(MainActivity.this, R.anim.push_left_out);
                viewFlipper.showPrevious();
            }
        });
        
        //調整窗口
        wmParams.gravity=Gravity.LEFT|Gravity.CENTER_VERTICAL;
        
        //顯示圖像
        wm.addView(btnLeft, wmParams);
    }
    
    /**
     * 設置右邊按鈕
     */
    private void createRightButtonView(){
        btnRight=new ImageView(this);
        btnRight.setImageResource(R.drawable.right);
        btnRight.setAlpha(0);
        
        btnRight.setOnClickListener(new View.OnClickListener() {    
            public void onClick(View arg0) {
                //下一個圖像
                viewFlipper.setInAnimation(MainActivity.this, R.anim.push_right_in);
                viewFlipper.setOutAnimation(MainActivity.this, R.anim.push_right_out);
                viewFlipper.showNext();
            }
        });
        
        //調整窗口
        wmParams.gravity=Gravity.RIGHT|Gravity.CENTER_VERTICAL;
        
        //顯示圖像
        wm.addView(btnRight, wmParams);
    }
    
    /**
     * 設置按鈕漸顯效果
     */
    private Handler mHandler = new Handler()
    {
        public void handleMessage(Message msg) {
            if(msg.what==1 && mAlpha<255){           
                //通過設置不透明度設置按鈕的漸顯效果
                mAlpha += 50;
                
                if(mAlpha>255)
                    mAlpha=255;
                
                btnLeft.setAlpha(mAlpha);
                btnLeft.invalidate();
                btnRight.setAlpha(mAlpha);
                btnRight.invalidate();
                
                if(!isHide && mAlpha<255)
                    mHandler.sendEmptyMessageDelayed(1, 100);
            }else if(msg.what==0 && mAlpha>0){
                mAlpha -= 10;
                
                if(mAlpha<0)
                    mAlpha=0;
                btnLeft.setAlpha(mAlpha);
                btnLeft.invalidate();
                btnRight.setAlpha(mAlpha);
                btnRight.invalidate();
                
                if(isHide && mAlpha>0)
                    mHandler.sendEmptyMessageDelayed(0, 800);
            }            
        }
    };
    
    private void showImageButtonView(){
        isHide = false;
        mHandler.sendEmptyMessage(1);
    }
    
    private void hideImageButtonView(){
        new Thread(){
            public void run() {
                try {
                    Thread.sleep(1500);
                    isHide = true;
                    mHandler.sendEmptyMessage(0);
                } catch (Exception e) {
                    ;
                }
            }
        }.start();
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_MOVE:
            case MotionEvent.ACTION_DOWN:
                showImageButtonView();            
                break;
            case MotionEvent.ACTION_UP:
                hideImageButtonView();                
                break;
        }
        
        return true;
    }

    @Override
    public void onDestroy(){
        super.onDestroy();
        //在程序退出(Activity銷毀）時銷毀窗口
        wm.removeView(btnLeft);
        wm.removeView(btnRight);
    }

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical">

<?xml version="1.0" encoding="utf-8"?> 

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate android:fromXDelta="0" android:toXDelta="-100%p"
        android:duration="500" />
    <alpha android:fromAlpha="1.0" android:toAlpha="0.1"
        android:duration="500" />

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate android:fromXDelta="0" android:toXDelta="100%p"
        android:duration="500" />
    <alpha android:fromAlpha="1.0" android:toAlpha="0.1"
        android:duration="500" />