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. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } @Override public View makeView() { // TODO Auto-generated method stub return null; } @Override public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub } @Override public 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ImageSwitcher private 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ID public 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
@Override public 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
@Override public View makeView() { // TODO Auto-generated method stub //创建ImageView ImageView 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;<br><br>import android.app.Activity;<br>import android.content.Context;<br>import android.os.Bundle;<br>import android.view.View; <br>import android.view.ViewGroup;<br>import android.view.Window;<br>import android.view.animation.AnimationUtils;<br>import android.widget.AdapterView;<br> import android.widget.BaseAdapter;<br>import android.widget.Gallery;<br>import android.widget.ImageSwitcher;<br>import android.widget.ImageView;<br> import android.widget.AdapterView.OnItemSelectedListener;<br>import android.widget.Gallery.LayoutParams;<br>import android.widget.ViewSwitcher.ViewFactory;<br><br> public class GalleryTest extends Activity implements OnItemSelectedListener,<br> ViewFactory {<br><br> private ImageSwitcher mSwitcher;<br><br> private Integer[] mThumbIds = { R.drawable.thumb0,<br> R.drawable.thumb1, R.drawable.thumb2, <br> R.drawable.thumb3, R.drawable.thumb4,<br> R.drawable.thumb5, R.drawable.thumb6,<br> R.drawable.thumb7 };<br><br> private Integer[] mImageIds = { R.drawable.img0, R.drawable.img1,<br> R.drawable.img2, R.drawable.img3, R.drawable.img4,<br> R.drawable.img5, R.drawable.img6, R.drawable.img7 };<br><br> @Override<br> public void onCreate(Bundle savedInstanceState) {<br> super.onCreate(savedInstanceState);<br><br> requestWindowFeature(Window.FEATURE_NO_TITLE);<br> setContentView(R.layout.main);<br> mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);<br> mSwitcher.setFactory(this);<br> mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,<br> android.R.anim.fade_in));<br> mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,<br> android.R.anim.fade_out));<br><br> Gallery g = (Gallery) findViewById(R.id.gallery);<br><br> g.setAdapter(new ImageAdapter(this)); g.setOnItemSelectedListener(this);<br><br> }<br><br> public class ImageAdapter extends BaseAdapter {<br> public ImageAdapter(Context c) {<br> mContext = c;<br> }<br> public int getCount() { <br> return mThumbIds.length;<br> }<br> public Object getItem(int position) { <br> return position;<br> }<br> public long getItemId(int position) { <br> return position;<br> }<br> public View getView(int position, View convertView, ViewGroup parent) {<br> ImageView i = new ImageView(mContext);<br><br> i.setImageResource(mThumbIds[position]); <br> i.setAdjustViewBounds(true);<br> i.setLayoutParams(new Gallery.LayoutParams(<br> LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); <br> i.setBackgroundResource(R.drawable.picturefrom);<br> return i;<br> }<br> private Context mContext;<br> }<br><br> @Override<br> public void onItemSelected(AdapterView<?> adapter, View v, int position,<br> long id) {<br> mSwitcher.setImageResource(mImageIds[position]);<br> }<br> <br> @Override<br> public void onNothingSelected(AdapterView<?> arg0) {<br><br> }<br><br> @Override<br> public View makeView() {<br> ImageView i = new ImageView(this);<br> i.setBackgroundColor(0xFF000000); <br> i.setScaleType(ImageView.ScaleType.FIT_CENTER);<br> i.setLayoutParams(new ImageSwitcher.LayoutParams(<br> LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));<br> return i;<br> }<br>}
<?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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