Android入门教程(二十四)------之Gallery + ImageSwitcher

   本文来自 http://blog.csdn.net/hellogv/ ，引用必须注明出处！

       上次讲了如何使用Gallery控件，这次就讲Gallery 与ImageSwitcher的结合使用，本文实现一个简单的浏览图片的功能。先贴出程序运行截图：

除了Gallery可以拖拉切换图片，我在ImageSwitcher控件加入了setOnTouchListener事件实现，使得ImageSwitcher也可以在拖拉中切换图片。本例子依然使用JAVA的反射机制来自动读取资源中的图片。

 

main.xml的源码如下:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageSwitcher android:id="@+id/switcher"
        android:layout_width="match_parent" android:layout_height="match_parent"/>

    <Gallery android:id="@+id/gallery"
        android:background="#55000000"
        android:layout_width="match_parent"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"

        android:gravity="center_vertical"
        android:spacing="16dp" android:layout_height="100dp"/>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageSwitcher android:id="@+id/switcher" android:layout_width="match_parent" android:layout_height="match_parent"/> <Gallery android:id="@+id/gallery" android:background="#55000000" android:layout_width="match_parent" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:gravity="center_vertical" android:spacing="16dp" android:layout_height="100dp"/> </RelativeLayout>

 

 

程序的源码如下:

package com.testImageView;
import java.lang.reflect.Field;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Gallery.LayoutParams;
import android.widget.ViewSwitcher.ViewFactory;
public class testImageView extends Activity implements ViewFactory {
    private ImageSwitcher is;
    private Gallery gallery;
    private int downX,upX;
    private ArrayList<Integer> imgList=new ArrayList<Integer>();//图像ID

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //用反射机制来获取资源中的图片ID
        Field[] fields = R.drawable.class.getDeclaredFields();
        for (Field field : fields)
        {
            if (!"icon".equals(field.getName()))//除了icon之外的图片
            {
                int index = 0;
                try {
                    index = field.getInt(R.drawable.class);
                } catch (IllegalArgumentException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IllegalAccessException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                //保存图片ID
                imgList.add(index);
            }
        }

        //设置ImageSwitcher控件
        is = (ImageSwitcher) findViewById(R.id.switcher);
        is.setFactory(this);
        is.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
        is.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));
        is.setOnTouchListener(new OnTouchListener(){
            /*
             * 在ImageSwitcher控件上滑动可以切换图片
             */
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if(event.getAction()==MotionEvent.ACTION_DOWN)
                {
                    downX=(int) event.getX();//取得按下时的坐标
                    return true;
                }
                else if(event.getAction()==MotionEvent.ACTION_UP)
                {
                    upX=(int) event.getX();//取得松开时的坐标
                    int index=0;
                    if(upX-downX>100)//从左拖到右，即看前一张
                    {
                        //如果是第一，则去到尾部
                        if(gallery.getSelectedItemPosition()==0)
                           index=gallery.getCount()-1;
                        else
                            index=gallery.getSelectedItemPosition()-1;
                    }
                    else if(downX-upX>100)//从右拖到左，即看后一张
                    {
                        //如果是最后，则去到第一
                        if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))
                            index=0;
                        else
                            index=gallery.getSelectedItemPosition()+1;
                    }
                    //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener
                    gallery.setSelection(index, true);
                    return true;
                }
                return false;
            }

        });

        //设置gallery控件
        gallery = (Gallery) findViewById(R.id.gallery);
        gallery.setAdapter(new ImageAdapter(this));
        gallery.setOnItemSelectedListener(new OnItemSelectedListener(){
            @Override
            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int position, long arg3) {
                is.setImageResource(imgList.get(position));
            }
            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub
            }

        });
    }
    //设置ImgaeSwitcher
    @Override
    public View makeView() {
        ImageView i = new ImageView(this);
        i.setBackgroundColor(0xFF000000);
        i.setScaleType(ImageView.ScaleType.CENTER);//居中
        i.setLayoutParams(new ImageSwitcher.LayoutParams(//自适应图片大小
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        return i;
    }
    public class ImageAdapter extends BaseAdapter {
        public ImageAdapter(Context c) {
            mContext = c;
        }
        public int getCount() {
            return imgList.size();
        }
        public Object getItem(int position) {
            return position;
        }
        public long getItemId(int position) {
            return position;
        }
        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i = new ImageView(mContext);
            i.setImageResource(imgList.get(position));
            i.setAdjustViewBounds(true);
            i.setLayoutParams(new Gallery.LayoutParams(
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            return i;
        }
        private Context mContext;
    }

}