Android入门第十三篇之Gallery + ImageSwitcher

Android入门第十三篇之Gallery + ImageSwitcher

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: view plainprint?

android:layout_width=\"match_parent\" android:layout_height=\"match_parent\">

android:layout_width=\"match_parent\" android:layout_height=\"match_parent\"/> 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\"/> 程序的源码如下: view plainprint?

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 imgList=new ArrayList();//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; } }