Android-ImageView图片视图Demo

代码

package com.lxt008;

import com.lxt008.R;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
import android.widget.TextView;

public class Activity01 extends Activity
{
    //声明ImageView对象
    ImageView    imageview;
    TextView    textview;
    //ImageView的alpha值，
    int            image_alpha    = 255;

    Handler        mHandler    = new Handler();
    //控件线程
    boolean        isrung        = false;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        isrung        = true;
        
        //获得ImageView的对象
        imageview = (ImageView) this.findViewById(R.id.ImageView01);
        textview = (TextView) this.findViewById(R.id.TextView01);
        
        //设置imageview的图片资源。同样可以再xml布局中像下面这样写
        //android:src="@drawable/logo"
        imageview.setImageResource(R.drawable.logo);
        
        //设置imageview的Alpha值
        imageview.setAlpha(image_alpha);

        //开启一个线程来让Alpha值递减
        new Thread(new Runnable() {
            public void run()
            {
                while (isrung)
                {
                    try
                    {

                        Thread.sleep(200);
                        //更新Alpha值
                        updateAlpha();
                    }
                    catch (InterruptedException e)
                    {
                        e.printStackTrace();
                    }
                }

            }
        }).start();

        //接受消息之后更新imageview视图
        mHandler = new Handler() {
            @Override
            public void handleMessage(Message msg)
            {
                super.handleMessage(msg);
                imageview.setAlpha(image_alpha);
                textview.setText("现在alpha值是："+Integer.toString(image_alpha));
                //更新
                imageview.invalidate();
            }
        };
    }
    
    public void updateAlpha()
    {
        if (image_alpha - 7 >= 0)
        {
            image_alpha -= 7;
        }
        else
        {
            image_alpha = 0;
            isrung = false;
        }
        //发送需要更新imageview视图的消息
        mHandler.sendMessage(mHandler.obtainMessage());
    }
}

 

布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<ImageView
    android:id="@+id/ImageView01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >
</ImageView>
<TextView
    android:id="@+id/TextView01"
    android:layout_below="@id/ImageView01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >
</TextView>
</LinearLayout>