Gallery與Spinner有共同父類:AbsPinner,說明Gallery與Spinner都是一個清單框。它們之間的差別在于Spinner顯示的是一個垂直的清單選擇框,而Gallery顯示的是一個水準的清單選擇框。Spinner的作用是供使用者選擇,而Gallery則允許使用者通過拖動檢視上一個,下一個。
Gallery用法與Spinner的用法形似,隻要為它提供一個内容Adapter就可以了。Adapter的getView方法傳回View作為Gallery清單的清單項。如果程式需要監控Gallery選擇項的改變,可以添加OnItemSelectedListener監聽即可。
Gallery 的xml屬性
下面通過一個幻燈片例子來熟悉Gallery
(1)activity_main.xml 布局一個ImageSwitcher 和Gallery ImageSwitcher用于顯示Gallery選中的圖檔
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<ImageSwitcher
android:id="@+id/imgSwt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Gallery
android:id="@+id/gallery"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="25dp"
android:unselectedAlpha="0.7"
android:spacing="2pt"/>
</LinearLayout>
(2)MainActivity.java
package com.example.gallery;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
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.ImageSwitcher;
import android.widget.ImageView;
import android.widget.RadioGroup.LayoutParams;
import android.widget.ViewSwitcher.ViewFactory;
public class MainActivity extends Activity {
//定義元件
private ImageSwitcher imgSwt = null;
private Gallery gallery = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//擷取布局元件
imgSwt = (ImageSwitcher) findViewById(R.id.imgSwt);
gallery = (Gallery) findViewById(R.id.gallery);
//圖檔
final int images[] = new int[]{
R.drawable.name01,R.drawable.name02,R.drawable.name03,
R.drawable.name04,R.drawable.name05,R.drawable.name06,
R.drawable.name07,R.drawable.name08,R.drawable.name09,
R.drawable.name10,R.drawable.name11,R.drawable.name12
};
//設定圖檔切換效果
imgSwt.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
imgSwt.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
//設定ViewFactory對象
imgSwt.setFactory(new ViewFactory() {
@Override
public View makeView() {
ImageView imageView = new ImageView(MainActivity.this);
imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageView.setLayoutParams(new ImageSwitcher.LayoutParams(350,350));
return imageView;
}
});
//建立BaseAdapter對象,負責提供Gallery顯示所有圖像
BaseAdapter adapter = new BaseAdapter() {
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//建立imageview
ImageView imageView = new ImageView(MainActivity.this);
imageView.setImageResource(images[position]);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
return imageView;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public int getCount() {
return images.length;
}
};
//給Gallery設定擴充卡
gallery.setAdapter(adapter);
//添加事件
gallery.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
imgSwt.setImageResource(images[position]);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// TODO Auto-generated method stub
}
});
}
}
運作效果如下: