android学习笔记23：幻灯片

使用gallary和imageswitcher可以在android中实现如windows中的幻灯片图片浏览效果。

用gallary作为下面的图片选择部分，imageSwitcher作为图片显示部分

<?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"><!-- 定义一个ImageSwitcher组件 --><ImageSwitcher android:id="@+id/switcher"android:layout_width="320dp"android:layout_height="320dp"/><!-- 定义一个Gallery组件 --><Gallery android:id="@+id/gallery"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_marginTop="25dp" android:unselectedAlpha="0.6"android:spacing="3pt"/></LinearLayout>

自定义一个BaseAdapter作为Gallary的数据源，设置一个setOnItemSelectedListener作为监听器，实时改变imageSwitcher中为图片，用TyoedArray保存Gallery中的属性值。

public class GallaryTest extends Activity{int[] imageIds = new int[]{R.drawable.shuangzi, R.drawable.shuangyu,R.drawable.chunv, R.drawable.tiancheng, R.drawable.tianxie,R.drawable.sheshou, R.drawable.juxie, R.drawable.shuiping,R.drawable.shizi, R.drawable.baiyang, R.drawable.jinniu,R.drawable.mojie };@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);final Gallery gallery = (Gallery) findViewById(R.id.gallery);// 获取显示图片的ImageSwitcher对象final ImageSwitcher switcher = (ImageSwitcher) findViewById(R.id.switcher);// 为ImageSwitcher对象设置ViewFactory对象switcher.setFactory(new ViewFactory(){@Overridepublic View makeView(){ImageView imageView = new ImageView(GallaryTest.this);imageView.setBackgroundColor(0xff0000);imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);imageView.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));return imageView;}});// 设置图片更换的动画效果switcher.setInAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_in));switcher.setOutAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_out));// 创建一个BaseAdapter对象，该对象负责提供Gallery所显示的图片BaseAdapter adapter = new BaseAdapter(){@Overridepublic int getCount(){return imageIds.length;}@Overridepublic Object getItem(int position){return position;}@Overridepublic long getItemId(int position){return position;}// 该方法的返回的View就是代表了每个列表项@Overridepublic View getView(int position, View convertView, ViewGroup parent){// 创建一个ImageViewImageView imageView = new ImageView(GallaryTest.this);imageView.setImageResource(imageIds[position % imageIds.length]);// 设置ImageView的缩放类型imageView.setScaleType(ImageView.ScaleType.FIT_XY); //把图片 不按比例 扩大/缩小到View的大小显示imageView.setLayoutParams(new Gallery.LayoutParams(75, 100));//用TyoedArray保存Gallery中的属性值TypedArray typedArray = obtainStyledAttributes(R.styleable.Gallery);imageView.setBackgroundResource(typedArray.getResourceId(R.styleable.Gallery_android_galleryItemBackground, 0));return imageView;}};gallery.setAdapter(adapter);gallery.setOnItemSelectedListener(new OnItemSelectedListener(){// 当Gallery选中项发生改变时触发该方法@Overridepublic void onItemSelected(AdapterView<?> parent, View view,int position, long id){switcher.setImageResource(imageIds[position % imageIds.length]);}@Overridepublic void onNothingSelected(AdapterView<?> parent){}});}}