Android 简单图片浏览器 ImageView

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:background="#66FFCC"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="400dp"
android:orientation="vertical"
android:gravity="center_horizontal"
>
<!-- 定义显示图片整体的ImageView -->
<ImageView
android:id="@+id/image1"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:scaleType="fitCenter"
android:src="@drawable/shuangta" />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_marginTop="3dp"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center">
<Button android:id="@+id/plus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="增大透明度"
/>
<Button android:id="@+id/minus"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="降低透明度"
/>
<Button android:id="@+id/next"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下一张"
/>
</LinearLayout>
</LinearLayout>

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public class MainActivity extends Activity {
//定义一个访问图片的数组
int [] images = new int[]{
R.drawable.lijiang,
R.drawable.qiao,
R.drawable.shuangta,
R.drawable.shui,
R.drawable.xiangbi,
};
//定义默认显示的图片
int currentImg = 2;
//定义图片的初始透明度
private int alpha = 255;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
final Button plus = (Button) findViewById(R.id.plus);
final Button minus = (Button) findViewById(R.id.minus);
final Button next = (Button) findViewById(R.id.next);
final ImageView image1 = (ImageView) findViewById(R.id.image1);
//定义查看下一张图片的监听器
next.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(currentImg >= 4) currentImg = -1;
BitmapDrawable bitmapDrawable = (BitmapDrawable) image1.getDrawable();
//如果图片还未回收，先强制回收图片
if(!bitmapDrawable.getBitmap().isRecycled()){
bitmapDrawable.getBitmap().isRecycled();
}
image1.setImageBitmap(BitmapFactory.decodeResource(getResources(), images[++currentImg]));
}
});
OnClickListener listener = new OnClickListener(){
@SuppressWarnings("deprecation")
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(v == plus) alpha += 50;
if(v == minus) alpha -= 50;
if(alpha >= 255) alpha = 255;
if(alpha <= 0) alpha = 0;
//改变图片的透明度
image1.setAlpha(alpha);
}
};
plus.setOnClickListener(listener);
minus.setOnClickListener(listener);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}