Android控件之Gallery用法实例分析

<&＃63;xml version="1.0" encoding="utf-8"&＃63;>

 
 
 

package com.ljq.ga;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.LinearLayout.LayoutParams;
import android.widget.ViewSwitcher.ViewFactory;
public class GalleryActivity extends Activity implements ViewFactory {
 private Gallery gallery = null;
 private ImageSwitcher imageSwitcher=null;
 int[] imageIDs={
   R.drawable.p1,R.drawable.p2,R.drawable.p3, 
   R.drawable.p4,R.drawable.p5,R.drawable.p6,
   R.drawable.p7,R.drawable.p8 };
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  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));
  gallery = (Gallery) findViewById(R.id.gallery);
  ImageViewAdapter adapter=new ImageViewAdapter(GalleryActivity.this, imageIDs);
  gallery.setAdapter(adapter);
  gallery.setOnItemSelectedListener(new OnItemSelectedListener(){
   public void onItemSelected(AdapterView<&＃63;> 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(imageIDs[position%imageIDs.length]);
   }
   public void onNothingSelected(AdapterView<&＃63;> arg0) {
   }
  });
  gallery.setOnItemClickListener(new OnItemClickListener(){
   public void onItemClick(AdapterView<&＃63;> parent, View view, int position, long id) {
    Log.i("ljq", "parent="+parent.getClass().getName()); //Gallery
    Log.i("ljq", "view="+view.getClass().getName()); //ImageView
    Log.i("ljq", "position=" + position); //1
    Log.i("ljq", "id=" + id);//1
    Gallery gl=(Gallery)parent;
    ImageView iv=(ImageView)view;
   }
  });
 }
 // 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;
 }
}

package com.ljq.ga;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class ImageViewAdapter extends BaseAdapter{
 private int[] imageIDs=null;
 private Context cOntext=null;
 public ImageViewAdapter(Context context, int[] imageIDs) {
  this.cOntext=context;
  this.imageIDs=imageIDs;
 }
 //用于返回图像总数，要注意的是，这个总数不能大于图像的实际数（可以小于图像的实际数），否则会抛出越界异常。
 public int getCount() {
  //优化一
  //return imageIDs.length;
  return Integer.MAX_VALUE;
 }
 public Object getItem(int position) {
  return imageIDs[position];
 }
 public long getItemId(int position) {
  return position;
 }
 //ScaleType的用法
 //CENTER/center 按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分显示
 //CENTER_CROP/centerCrop 按比例扩大图片的size居中显示，使得图片长 (宽)等于或大于View的长(宽)
 //CENTER_INSIDE/centerInside 将图片的内容完整居中显示，通过按比例缩小 或原来的size使得图片长/宽等于或小于View的长/宽
 //FIT_CENTER/fitCenter 把图片按比例扩大/缩小到View的宽度，居中显示
 //FIT_END/fitEnd 把 图片按比例扩大/缩小到View的宽度，显示在View的下部分位置
 //FIT_START/fitStart 把 图片按比例扩大/缩小到View的宽度，显示在View的上部分位置
 //FIT_XY/fitXY 把图片 不按比例 扩大/缩小到View的大小显示
 //MATRIX/matrix 用矩阵来绘制
 public View getView(int position, View convertView, ViewGroup parent) {
  ImageView iv = new ImageView(context);
  //优化二，通过取余来循环取得imageIDs数组中的图像资源ID，取余可以大大较少资源的浪费
  iv.setImageResource(imageIDs[position%imageIDs.length]);
  iv.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
  iv.setLayoutParams(new LinearLayout.LayoutParams(77,77));//把图片缩小原来的60%
  return iv;
 }
}