Android应用开发学习之图片切换器

作者：刘昊昱

博客：http://blog.csdn.net/liuhaoyutz

如果我们要实现类似Windows的照片查看器切换上一张下一张照片的效果，可以使用图片切换器ImageSwitcher，下面我们来看一个例子，其运行效果如下所示：

先来看主布局文件main.xml，其内容如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:orientation="vertical" > <ImageSwitcher
android:id="@+id/imageSwitcher"
android:layout_width="300px"
android:layout_height="300px"/>" <LinearLayout
android:orientation="horizontal"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"> <Button
android:text="上一张"
android:id="@+id/button1"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Button
android:text="下一张"
android:id="@+id/button2"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout></LinearLayout>

下面来看主Activity文件，其内容如下：

package com.liuhaoyu;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;public class MainActivity extends Activity {
private int[] imageId = new int[] { R.drawable.img01, R.drawable.img02,
R.drawable.img03, R.drawable.img04, R.drawable.img05,
R.drawable.img06, R.drawable.img07, R.drawable.img08};
private int index = 0;
private ImageSwitcher imageSwitcher; /** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main); imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher);
imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_in));
imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_out));
imageSwitcher.setFactory(new ViewFactory() {
@Override
public View makeView() {
ImageView imageView = new ImageView(MainActivity.this);
imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageView.setLayoutParams(new ImageSwitcher.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
return imageView;
}
});
imageSwitcher.setImageResource(imageId[index]);Button previous = (Button) findViewById(R.id.button1);
Button next = (Button) findViewById(R.id.button2);
previous.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (index > 0) {
index--;
} else {
index = imageId.length - 1;
}
imageSwitcher.setImageResource(imageId[index]);
}
});
next.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (index < imageId.length - 1) {
index++;
} else {
index = 0;
}
imageSwitcher.setImageResource(imageId[index]);
}
});
}
}