Android 高级UI设计笔记13：Gallery（画廊控件）之 循环显示图像

resIds[position % resIds.length]

[b]

 <?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:orientation="vertical" >

<Gallery
android:id="@+id/gallery"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="30dp" />

<ImageSwitcher
android:id="@+id/imageswitcher"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="30dp" />

</LinearLayout>

 package com.himi.gallerycycleimage;

import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.Gallery.LayoutParams;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;

public class MainActivity extends Activity implements OnItemSelectedListener, ViewFactory {
private Gallery gallery;
private ImageSwitcher imageSwitcher;
private ImageAdapter imageAdapter;
private int[] resIds = new int[] { R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4,
R.drawable.img5, R.drawable.img6 };

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

gallery = (Gallery) findViewById(R.id.gallery);
imageAdapter = new ImageAdapter(this);
gallery.setAdapter(imageAdapter);
gallery.setOnItemSelectedListener(this);

imageSwitcher = (ImageSwitcher) findViewById(R.id.imageswitcher);
// 设置ImageSwitcher组件的工厂对象
imageSwitcher.setFactory(this);
// 设置ImageSwitcher组件显示图像的动画效果
imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
}

public class ImageAdapter extends BaseAdapter {
int mGalleryItemBackground;
private Context mContext;

public ImageAdapter(Context context) {
mContext = context;
TypedArray typedArray = obtainStyledAttributes(R.styleable.Gallery);
mGalleryItemBackground = typedArray.getResourceId(R.styleable.Gallery_android_galleryItemBackground, 0);
}

// 第1点改进，返回一个很大的值，例如，Integer.MAX_VALUE
public int getCount() {
return Integer.MAX_VALUE;
}

public Object getItem(int position) {
return position;
}

public long getItemId(int position) {
return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView = new ImageView(mContext);
// 第2点改进，通过取余来循环取得resIds数组中的图像资源ID
imageView.setImageResource(resIds[position % resIds.length]);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setLayoutParams(new Gallery.LayoutParams(163, 106));
imageView.setBackgroundResource(mGalleryItemBackground);
return imageView;
}
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
// 选中Gallery中某个图像时，在ImageSwitcher组件中放大显示该图像
imageSwitcher.setImageResource(resIds[position % resIds.length]);
}

@Override
public void onNothingSelected(AdapterView<?> parent) {
}

// ImageSwitcher组件需要这个方法来创建一个View对象（一般为ImageView对象）
// 来显示图像
public View makeView() {
ImageView imageView = new ImageView(this);
imageView.setBackgroundColor(0xFF000000);
imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageView.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
return imageView;
}

}

 <?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="Gallery">
<attr name="android:galleryItemBackground" />
</declare-styleable>
</resources>