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Gallery能够水平显示其内容,一般用来浏览图片,被选中的选项位于中间,并且可以相应事件显示信息。下面结合ImageSwitcher组件来实现一个通过缩略图来浏览图片的程序,具体步骤如下
第一步:
创建一个Andorid工程”GalleryTest”,该工程的入口是Activity类GalleryTest继承Activity并实现OnItemSelectedListener和ViewFactory接口,来实现图片和视图的创建
package org.hualang.Gallery;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ViewSwitcher.ViewFactory;
//继承Activity,实现onItemSelectedListener和ViewFactory接口
public class GalleryTest extends Activity implements OnItemSelectedListener,ViewFactory{/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);}@Overridepublic View makeView() {// TODO Auto-generated method stubreturn null;}@Overridepublic void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,long arg3) {// TODO Auto-generated method stub}@Overridepublic void onNothingSelected(AdapterView<?> arg0) {// TODO Auto-generated method stub}
}
第二步:
在工程的res\drawable\目录下添加7张图片和对应的缩略图
第三步:
在工程res\layout\目录下创建一个布局文件main.xml,在其中那个添加一个Gallery组件和一个ImageSwitcher组件,并设置相应的属性
<?xml version="1.0" encoding="utf-8"?> <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/switcher"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_alignParentTop="true"android:layout_alignParentLeft="true"/><Gallery android:id="@+id/gallery"android:background="#55000000"android:layout_width="fill_parent"android:layout_height="60dp"android:layout_alignParentBottom="true"android:layout_alignParentLeft="true"android:gravity="center_vertical"android:spacing="16dp"/> </LinearLayout>
第四步:在GalleryTest顶部声明使用到的ImageSwitcher实例图片资源Integer数组
public class GalleryTest extends Activity implements OnItemSelectedListener,ViewFactory{/** Called when the activity is first created. *///声明ImageSwitcherprivate ImageSwitcher switcher;//缩略图片id数组private Integer[] thumbids={R.drawable.thumb0,R.drawable.thumb1,R.drawable.thumb2,R.drawable.thumb3,R.drawable.thumb4,R.drawable.thumb5,R.drawable.thumb6,R.drawable.thumb7};//图片id数组private Integer[] imgids={R.drawable.img0,R.drawable.img1,R.drawable.img2,R.drawable.img3,R.drawable.img4,R.drawable.img5,R.drawable.img6,R.drawable.img7};
第五步:
在GalleryTest的onCreate()方法中,将窗口样式设置为无标题,设置当前布局视图,获得ImageSwitcher实例,并设置渐进渐出动画,获得Gallery实例
public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//设置窗口特征无标题requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.main);//通过findViewById方法获得ImageSwitcher对象switcher=(ImageSwitcher)findViewById(R.id.switcher);//为ImageSwitcher设置工厂switcher.setFactory(this);//设置动画渐入效果switcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));//设置动画渐出效果switcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));//通过findViewById方法获得Gallery对象Gallery g=(Gallery)findViewById(R.id.gallery);}
第六步:
创建内部类ImageAdapter,该类继承BaseAdapter,为Gallery设置Adapter实例
public class ImageAdapter extends BaseAdapter {//构造方法public ImageAdapter(Context c) {mContext = c;}//获得数量public int getCount() {return thumbids.length;}//获得当前选项public Object getItem(int position) {return position;}//获得当前选项IDpublic long getItemId(int position) {return position;}//获得View对象public View getView(int position, View convertView, ViewGroup parent) {//实例化ImageView对象ImageView i = new ImageView(mContext);//设置缩略图片资源i.setImageResource(thumbids[position]);//设置边界对齐i.setAdjustViewBounds(true);//设置布局参数i.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));//设置背景资源i.setBackgroundResource(R.drawable.picturefrom);return i;}private Context mContext;}
第七步:
实现onItemSelected()方法,更换图片
@Overridepublic void onItemSelected(AdapterView<?> adapter, View v, int position,long id) {switcher.setImageResource(imgids[position]);}
第八步:
实现makeView()方法,为ImageView设置布局格式
@Overridepublic View makeView() {// TODO Auto-generated method stub//创建ImageViewImageView i=new ImageView(this);//设置背景颜色i.setBackgroundColor(0xFF000000);//设置精度类型i.setScaleType(ImageView.ScaleType.FIT_CENTER);//设置布局参数i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));return i;}
第九步:
为Gallery添加Adapter并添加OnItemSelectedListener监听器
g.setAdapter(new ImageAdapter(this));g.setOnItemSelectedListener(this);
至此,全部,结束,运行结果如下
完整源代码:
package org.hualang.Gallery;import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
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 GalleryTest extends Activity implements OnItemSelectedListener,ViewFactory {private ImageSwitcher mSwitcher;private Integer[] mThumbIds = { R.drawable.thumb0,R.drawable.thumb1, R.drawable.thumb2,R.drawable.thumb3, R.drawable.thumb4,R.drawable.thumb5, R.drawable.thumb6,R.drawable.thumb7 };private Integer[] mImageIds = { R.drawable.img0, R.drawable.img1,R.drawable.img2, R.drawable.img3, R.drawable.img4,R.drawable.img5, R.drawable.img6, R.drawable.img7 };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.main);mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);mSwitcher.setFactory(this);mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_in));mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_out));Gallery g = (Gallery) findViewById(R.id.gallery);g.setAdapter(new ImageAdapter(this));g.setOnItemSelectedListener(this);}public class ImageAdapter extends BaseAdapter {public ImageAdapter(Context c) {mContext = c;}public int getCount() {return mThumbIds.length;}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(mThumbIds[position]);i.setAdjustViewBounds(true);i.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));i.setBackgroundResource(R.drawable.picturefrom);return i;}private Context mContext;}@Overridepublic void onItemSelected(AdapterView<?> adapter, View v, int position,long id) {mSwitcher.setImageResource(mImageIds[position]);}@Overridepublic void onNothingSelected(AdapterView<?> arg0) {}@Overridepublic View makeView() {ImageView i = new ImageView(this);i.setBackgroundColor(0xFF000000);i.setScaleType(ImageView.ScaleType.FIT_CENTER);i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));return i;}
}
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"> <ImageSwitcher android:id="@+id/switcher"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_alignParentTop="true"android:layout_alignParentLeft="true"/> <Gallery android:id="@+id/gallery"android:background="#55000000"android:layout_width="fill_parent"android:layout_height="60dp"android:layout_alignParentBottom="true"android:layout_alignParentLeft="true"android:gravity="center_vertical"android:spacing="16dp"/> </RelativeLayout>
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