【Android开发学习31】Gallery之初体验--实现手指直接拖动图片移动

一、基础知识:

要实现这一效果，需要一个容器来存放Gallrey显示的图片，这里使用一个继承自BaseAdapter类的派生类来装这些图片。
我们需要监听其事件setOnItemClickListener,从而确定用户当前选中的是哪一张图片。
首先，需要将所有要显示的图片的索引存放在一个int型数组中，然后通过setImageResource方法来设置ImageView要显示的图片资源，最后将
每张图片的ImageView显示在屏幕上。

二、代码展示:

1."main.xml"

<?xml version="1.0" encoding="utf-8"?><Gallery xmlns:android="http://schemas.android.com/apk/res/android"   android:id="@+id/Gallery01"  android:layout_width="fill_parent"  android:layout_height="wrap_content"/>

2."Activity01.java"

package com.yarin.android.XX;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.Gallery;import android.widget.Toast;import android.widget.AdapterView.OnItemClickListener;public class Activity01 extends Activity{/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);//获得Gallery对象Gallery g = (Gallery) findViewById(R.id.Gallery01);//添加ImageAdapter给Gallery对象g.setAdapter(new ImageAdapter(this));//设置Gallery的背景g.setBackgroundResource(R.drawable.bg0);//设置Gallery的事件监听g.setOnItemClickListener(new OnItemClickListener() {public void onItemClick(AdapterView<?> parent, View v, int position, long id){        Toast.makeText(Activity01.this,"你选择了"+(position+1)+" 号图片",             Toast.LENGTH_SHORT).show();}});}}

3."ImageAdapter.java"

package com.yarin.android.XX;import android.content.Context;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.Gallery;import android.widget.ImageView;public class ImageAdapter extends BaseAdapter{// 定义Contextprivate ContextmContext;// 定义整型数组 即图片源private Integer[]mImageIds = { R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5, R.drawable.img6, R.drawable.img7,R.drawable.img8,};// 声明 ImageAdapterpublic ImageAdapter(Context c){mContext = c;}// 获取图片的个数public int getCount(){return mImageIds.length;}// 获取图片在库中的位置public Object getItem(int position){return position;}// 获取图片IDpublic long getItemId(int position){return position;}public View getView(int position, View convertView, ViewGroup parent){ImageView imageview = new ImageView(mContext);// 给ImageView设置资源imageview.setImageResource(mImageIds[position]);// 设置布局 图片120×120显示imageview.setLayoutParams(new Gallery.LayoutParams(120, 120));// 设置显示比例类型imageview.setScaleType(ImageView.ScaleType.FIT_CENTER);return imageview;}}

三、效果展示: