Android回部古劍之ViewFlipper之仙人指路

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回部古劍
        霍青桐一定神，說道：“我性命承公子相救，族中聖物，又蒙公子奪回。不論公子如何待我，都決不怨你。”說到這裡，伸手解下腰間短劍，說道：“這短劍是我爹爹所賜，據說劍裡藏著一個極大秘密，幾百年來輾轉相傳，始終無人參詳得出。今日一別，後會無期，此劍請公子收下。公子慧人，或能解得劍中奧妙。”
        今天我們學習如何利用Android平台"回部古劍"ViewFlipper配合點擊按鈕的操作來實現左右滑動浏覽圖片的功能，像我們平日裡在手機上查看電子相冊、浏覽電子書時所使用滑動翻頁操作，都可以用它來實現。跟上一篇講到利用ViewFlipper配合手勢操作來實現該功能相比，可以說是各有千秋。按鈕是有漸變效果的，也就是說點擊圖片時按鈕會立即顯示，松開後按鈕會慢慢消失。下面給出該情景的案例：
一、案例技術要點
1.創建一個ViewFlipper控件，並且為它增加用於顯示圖片內容的視圖。
2.使用WindowManager窗口管理器及其LayoutParams布局參數來設置導航按鈕的布局和參數。改變Window設置需要添加如下權限：
[html] 
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/> 

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>3.創建導航按鈕，並且為它們分別設置進出屏幕的動畫效果。
4.通過Handler異步消息處理機制來改變導航按鈕顯示的透明度，從而達到漸變顯示的效果。
5.重寫當前Activity的觸摸事件回調方法onTouchEvent()：當手指按住移動圖片或點擊圖片時顯示導航按鈕；當手指離開圖片時逐漸消失導航按鈕。
二、案例代碼陳列
工程包目錄

AndroidManifest.xml

[html] 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="cn.lynn.viewflipper" 
    android:versionCode="1" 
    android:versionName="1.0" > 
 
    <uses-sdk 
        android:minSdkVersion="8" 
        android:targetSdkVersion="15" /> 
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/> 
    <application 
        android:icon="@drawable/ic_launcher" 
        android:label="@string/app_name" > 
        <activity 
            android:name=".ViewFlipperMainActivity" 
            android:label="@string/app_name" > 
            <intent-filter> 
                <action android:name="android.intent.action.MAIN" /> 
 
                <category android:name="android.intent.category.LAUNCHER" /> 
            </intent-filter> 
        </activity> 
    </application> 
 
</manifest> 

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.lynn.viewflipper"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".ViewFlipperMainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>strings.xml
[html] 
<resources> 
 
    <string name="app_name">android圖片水平滑動ViewFlipper</string> 
 
</resources> 

<resources>

    <string name="app_name">android圖片水平滑動ViewFlipper</string>

</resources>main.xml
[html] 
<?xml version="1.0" encoding="utf-8" ?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical"> 
     
    <ViewFlipper  
        android:id="@+id/viewFlipper" 
        android:layout_width="match_parent" 
        android:layout_height="match_parent"> 
         
        <LinearLayout  
            android:layout_width="match_parent" 
            android:layout_height="match_parent" 
            android:gravity="center"> 
            <ImageView  
                android:layout_width="160dp" 
                android:layout_height="160dp" 
                android:src="@drawable/item1"/> 
        </LinearLayout> 
         
        <LinearLayout  
            android:layout_width="match_parent" 
            android:layout_height="match_parent" 
            android:gravity="center"> 
            <ImageView  
                android:layout_width="160dp" 
                android:layout_height="160dp" 
                android:src="@drawable/item2"/> 
        </LinearLayout> 
         
        <LinearLayout  
            android:layout_width="match_parent" 
            android:layout_height="match_parent" 
            android:gravity="center"> 
            <ImageView  
                android:layout_width="160dp" 
                android:layout_height="160dp" 
                android:src="@drawable/item3"/> 
        </LinearLayout> 
         
        <LinearLayout  
            android:layout_width="match_parent" 
            android:layout_height="match_parent" 
            android:gravity="center"> 
            <ImageView  
                android:layout_width="160dp" 
                android:layout_height="160dp" 
                android:src="@drawable/item4"/> 
        </LinearLayout> 
         
        <LinearLayout  
            android:layout_width="match_parent" 
            android:layout_height="match_parent" 
            android:gravity="center"> 
            <ImageView  
                android:layout_width="160dp" 
                android:layout_height="160dp" 
                android:src="@drawable/item5"/> 
        </LinearLayout> 
         
    </ViewFlipper> 
 
</LinearLayout> 

<?xml version="1.0" encoding="utf-8" ?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
   
    <ViewFlipper
        android:id="@+id/viewFlipper"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
       
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:layout_width="160dp"
                android:layout_height="160dp"
                android:src="@drawable/item1"/>
        </LinearLayout>
       
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:layout_width="160dp"
                android:layout_height="160dp"
                android:src="@drawable/item2"/>
        </LinearLayout>
       
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:layout_width="160dp"
                android:layout_height="160dp"
                android:src="@drawable/item3"/>
        </LinearLayout>
       
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:layout_width="160dp"
                android:layout_height="160dp"
                android:src="@drawable/item4"/>
        </LinearLayout>
       
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:layout_width="160dp"
                android:layout_height="160dp"
                android:src="@drawable/item5"/>
        </LinearLayout>
       
    </ViewFlipper>

</LinearLayout>
圖片左進動畫：left_in.xml[html] view plaincopyprint?
<?xml version="1.0" encoding="utf-8"?>   
<set xmlns:android="http://schemas.android.com/apk/res/android"> 
    <translate android:fromXDelta="100%p" android:toXDelta="0" 
        android:duration="500" /> 
    <alpha android:fromAlpha="0.1" android:toAlpha="1.0" 
        android:duration="500" /> 
</set> 

<?xml version="1.0" encoding="utf-8"?> 
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <translate android:fromXDelta="100%p" android:toXDelta="0"
        android:duration="500" />
    <alpha android:fromAlpha="0.1" android:toAlpha="1.0"
        android:duration="500" />
</set>圖片左出動畫：left_out.xml[html] view plaincopyprint?
<?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" /> 
</set> 

<?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" />
</set>圖片右進動畫：right_in.xml[html] view plaincopyprint?
<?xml version="1.0" encoding="utf-8"?>  
<set xmlns:android="http://schemas.android.com/apk/res/android"> 
    <translate android:fromXDelta="-100%p" android:toXDelta="0" 
        android:duration="500" /> 
    <alpha android:fromAlpha="0.1" android:toAlpha="1.0" 
        android:duration="500" /> 
</set> 

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

[html] 
<?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" /> 
</set> 

<?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" />
</set>ViewFlipperMainActivity.java
[java] 
package cn.lynn.viewflipper; 
 
import android.app.Activity; 
import android.content.Context; 
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.View.OnClickListener; 
import android.view.WindowManager; 
import android.view.WindowManager.LayoutParams; 
import android.widget.ImageView; 
import android.widget.ViewFlipper; 
 
/**
 * ViewFlipper實現水平滑動圖片，需要點擊按鈕指引滑動
 * 
 * @author lynnli1229
 */ 
public class ViewFlipperMainActivity extends Activity { 
 
    private static final int SHOW = 0x29; 
    private static final int HIDE = 0x31; 
 
    private ImageView leftBtnView; 
    private ImageView rightBtnView; 
 
    // 設置窗口管理器  
    private WindowManager winMgr; 
    // 設置窗口管理器布局參數  
    private WindowManager.LayoutParams winMgrParams; 
 
    // 設置按鈕視圖alpha的初始值  
    private int alpha; 
    // 設置按鈕是否隱藏  
    private boolean isHide; 
 
    private ViewFlipper viewFlipper; 
 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
 
        viewFlipper = (ViewFlipper) findViewById(R.id.viewFlipper); 
 
        initBtnView(); 
    } 
 
    /**
     * 初始化按鈕視圖
     */ 
    private void initBtnView() { 
        winMgr = (WindowManager) getSystemService(Context.WINDOW_SERVICE); 
        winMgrParams = new WindowManager.LayoutParams(); 
        winMgrParams.type = LayoutParams.TYPE_PHONE; 
        // 設置圖片背景為透明  
        winMgrParams.format = PixelFormat.RGBA_8888; 
        winMgrParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL 
                | LayoutParams.FLAG_NOT_FOCUSABLE; 
 
        winMgrParams.x = 0; 
        winMgrParams.y = 0; 
 
        winMgrParams.width = 48; 
        winMgrParams.height = 48; 
 
        createLeftBtnView(); 
        createRightBtnView(); 
    } 
 
    /**
     * 創建向左（前）按鈕
     */ 
    private void createLeftBtnView() { 
        leftBtnView = new ImageView(this); 
        leftBtnView.setImageResource(R.drawable.left); 
        leftBtnView.setAlpha(0); 
 
        leftBtnView.setOnClickListener(new OnClickListener() { 
            public void onClick(View view) { 
                // 上一個圖像  
                viewFlipper.setInAnimation(ViewFlipperMainActivity.this, 
                        R.anim.left_in); 
                viewFlipper.setOutAnimation(ViewFlipperMainActivity.this, 
                        R.anim.left_out); 
                viewFlipper.showPrevious(); 
            } 
        }); 
 
        // 調整窗口  
        winMgrParams.gravity = Gravity.LEFT | Gravity.CENTER_VERTICAL; 
        // 顯示圖像  
        winMgr.addView(leftBtnView, winMgrParams); 
    } 
 
    /**
     * 創建向右（後）按鈕
     */ 
    private void createRightBtnView() { 
        rightBtnView = new ImageView(this); 
        rightBtnView.setImageResource(R.drawable.right); 
        rightBtnView.setAlpha(0); 
 
        rightBtnView.setOnClickListener(new OnClickListener() { 
            @Override 
            public void onClick(View view) { 
                // 下一個圖像  
                viewFlipper.setInAnimation(ViewFlipperMainActivity.this, 
                        R.anim.right_in); 
                viewFlipper.setOutAnimation(ViewFlipperMainActivity.this, 
                        R.anim.right_out); 
                viewFlipper.showNext(); 
            } 
        }); 
 
        // 調整窗口  
        winMgrParams.gravity = Gravity.RIGHT | Gravity.CENTER_VERTICAL; 
        // 顯示圖像  
        winMgr.addView(rightBtnView, winMgrParams); 
    } 
 
    /**
     * 設置按鈕漸變顯示效果
     */ 
    private final Handler handler = new Handler() { 
        @Override 
        public void handleMessage(Message msg) { 
            if (msg.what == SHOW && alpha < 255) { 
                // 增加按鈕的不透明度  
                alpha += 50; 
                // 溢出則重置  
                if (alpha > 255) { 
                    alpha = 255; 
                } 
                leftBtnView.setAlpha(alpha); 
                leftBtnView.invalidate(); // 在主線程中刷新視圖  
                rightBtnView.setAlpha(alpha); 
                rightBtnView.invalidate(); 
 
                if (!isHide && alpha < 255) 
                    handler.sendEmptyMessageDelayed(SHOW, 100); 
            } else if (msg.what == HIDE && alpha > 0) { 
                // 增加按鈕的透明度  
                alpha -= 25; 
                // 溢出則重置  
                if (alpha < 0) { 
                    alpha = 0; 
                } 
                leftBtnView.setAlpha(alpha); 
                leftBtnView.invalidate(); 
                rightBtnView.setAlpha(alpha); 
                rightBtnView.invalidate(); 
 
                if (isHide && alpha > 0) 
                    handler.sendEmptyMessageDelayed(HIDE, 500); 
            } 
        } 
    }; 
 
    private void showBtnView() { 
        isHide = false; 
        handler.sendEmptyMessage(SHOW); 
    } 
 
    private void hideBtnView() { 
        new Thread() { 
            public void run() { 
                try { 
                    Thread.sleep(1000); // 休眠1秒，為了達到更好的演示效果  
                    isHide = true; 
                    handler.sendEmptyMessage(HIDE); 
                } catch (Exception e) { 
                } 
            } 
        }.start(); 
    } 
 
    @Override 
    public boolean onTouchEvent(MotionEvent event) { 
        switch (event.getAction()) { 
        case MotionEvent.ACTION_MOVE: // 手指按住移動圖片  
        case MotionEvent.ACTION_DOWN: // 手指點擊圖片  
            showBtnView(); 
            break; 
        case MotionEvent.ACTION_UP: 
            hideBtnView(); 
            break; 
        } 
 
        return true; 
    } 
 
    @Override 
    public void onDestroy() { 
        super.onDestroy(); 
        // 銷毀導航按鈕視圖  
        winMgr.removeView(leftBtnView); 
        winMgr.removeView(rightBtnView); 
    } 
} 

package cn.lynn.viewflipper;

import android.app.Activity;
import android.content.Context;
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.View.OnClickListener;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;
import android.widget.ImageView;
import android.widget.ViewFlipper;

/**
 * ViewFlipper實現水平滑動圖片，需要點擊按鈕指引滑動
 *
 * @author lynnli1229
 */
public class ViewFlipperMainActivity extends Activity {

    private static final int SHOW = 0x29;
    private static final int HIDE = 0x31;

    private ImageView leftBtnView;
    private ImageView rightBtnView;

    // 設置窗口管理器
    private WindowManager winMgr;
    // 設置窗口管理器布局參數
    private WindowManager.LayoutParams winMgrParams;

    // 設置按鈕視圖alpha的初始值
    private int alpha;
    // 設置按鈕是否隱藏
    private boolean isHide;

    private ViewFlipper viewFlipper;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        viewFlipper = (ViewFlipper) findViewById(R.id.viewFlipper);

        initBtnView();
    }

    /**
     * 初始化按鈕視圖
     */
    private void initBtnView() {
        winMgr = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        winMgrParams = new WindowManager.LayoutParams();
        winMgrParams.type = LayoutParams.TYPE_PHONE;
        // 設置圖片背景為透明
        winMgrParams.format = PixelFormat.RGBA_8888;
        winMgrParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL
                | LayoutParams.FLAG_NOT_FOCUSABLE;

        winMgrParams.x = 0;
        winMgrParams.y = 0;

        winMgrParams.width = 48;
        winMgrParams.height = 48;

        createLeftBtnView();
        createRightBtnView();
    }

    /**
     * 創建向左（前）按鈕
     */
    private void createLeftBtnView() {
        leftBtnView = new ImageView(this);
        leftBtnView.setImageResource(R.drawable.left);
        leftBtnView.setAlpha(0);

        leftBtnView.setOnClickListener(new OnClickListener() {
            public void onClick(View view) {
                // 上一個圖像
                viewFlipper.setInAnimation(ViewFlipperMainActivity.this,
                        R.anim.left_in);
                viewFlipper.setOutAnimation(ViewFlipperMainActivity.this,
                        R.anim.left_out);
                viewFlipper.showPrevious();
            }
        });

        // 調整窗口
        winMgrParams.gravity = Gravity.LEFT | Gravity.CENTER_VERTICAL;
        // 顯示圖像
        winMgr.addView(leftBtnView, winMgrParams);
    }

    /**
     * 創建向右（後）按鈕
     */
    private void createRightBtnView() {
        rightBtnView = new ImageView(this);
        rightBtnView.setImageResource(R.drawable.right);
        rightBtnView.setAlpha(0);

        rightBtnView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                // 下一個圖像
                viewFlipper.setInAnimation(ViewFlipperMainActivity.this,
                        R.anim.right_in);
                viewFlipper.setOutAnimation(ViewFlipperMainActivity.this,
                        R.anim.right_out);
                viewFlipper.showNext();
            }
        });

        // 調整窗口
        winMgrParams.gravity = Gravity.RIGHT | Gravity.CENTER_VERTICAL;
        // 顯示圖像
        winMgr.addView(rightBtnView, winMgrParams);
    }

    /**
     * 設置按鈕漸變顯示效果
     */
    private final Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == SHOW && alpha < 255) {
                // 增加按鈕的不透明度
                alpha += 50;
                // 溢出則重置
                if (alpha > 255) {
                    alpha = 255;
                }
                leftBtnView.setAlpha(alpha);
                leftBtnView.invalidate(); // 在主線程中刷新視圖
                rightBtnView.setAlpha(alpha);
                rightBtnView.invalidate();

                if (!isHide && alpha < 255)
                    handler.sendEmptyMessageDelayed(SHOW, 100);
            } else if (msg.what == HIDE && alpha > 0) {
                // 增加按鈕的透明度
                alpha -= 25;
                // 溢出則重置
                if (alpha < 0) {
                    alpha = 0;
                }
                leftBtnView.setAlpha(alpha);
                leftBtnView.invalidate();
                rightBtnView.setAlpha(alpha);
                rightBtnView.invalidate();

                if (isHide && alpha > 0)
                    handler.sendEmptyMessageDelayed(HIDE, 500);
            }
        }
    };

    private void showBtnView() {
        isHide = false;
        handler.sendEmptyMessage(SHOW);
    }

    private void hideBtnView() {
        new Thread() {
            public void run() {
                try {
                    Thread.sleep(1000); // 休眠1秒，為了達到更好的演示效果
                    isHide = true;
                    handler.sendEmptyMessage(HIDE);
                } catch (Exception e) {
                }
            }
        }.start();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_MOVE: // 手指按住移動圖片
        case MotionEvent.ACTION_DOWN: // 手指點擊圖片
            showBtnView();
            break;
        case MotionEvent.ACTION_UP:
            hideBtnView();
            break;
        }

        return true;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        // 銷毀導航按鈕視圖
        winMgr.removeView(leftBtnView);
        winMgr.removeView(rightBtnView);
    }
}
三、案例效果展示