Android之Gallery

一. 初步认识

src

package cn.android.lyj; import android.app.Activity; import android.content.Context; import android.content.res.TypedArray; import android.os.Bundle; import android.view.ContextMenu; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.view.ContextMenu.ContextMenuInfo; import android.widget.AdapterView; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageView; import android.widget.Toast; import android.widget.AdapterView.AdapterContextMenuInfo; import android.widget.AdapterView.OnItemClickListener; public class Activity_01 extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // Reference the Gallery view Gallery g = (Gallery) findViewById(R.id.gallery); // Set the adapter to our custom adapter (below) g.setAdapter(new ImageAdapter(this)); // Set a item click listener, and just Toast the clicked position g.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView parent, View v, int position, long id) { Toast.makeText(Activity_01.this, "" + position, Toast.LENGTH_SHORT).show(); } }); // We also want to show context menu for longpressed items in the // gallery registerForContextMenu(g); } @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { menu.add(R.string.gallery_2_text); menu.add("hello"); } @Override public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo(); Toast.makeText(this, "Longpress: " + info.position, Toast.LENGTH_SHORT).show(); return true; } public class ImageAdapter extends BaseAdapter { int mGalleryItemBackground; public ImageAdapter(Context c) { mContext = c; TypedArray a = obtainStyledAttributes(R.styleable.Gallery1); mGalleryItemBackground = a.getResourceId(R.styleable.Gallery1_android_galleryItemBackground, 0); a.recycle(); } public int getCount() { return mImageIds.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(mImageIds[position]); i.setScaleType(ImageView.ScaleType.FIT_XY); //图片在北京图片中得位置 i.setLayoutParams(new Gallery.LayoutParams(136, 88)); //修改存放此图片的view的大小比例 // The preferred Gallery item background i.setBackgroundResource(mGalleryItemBackground); return i; } private Context mContext; private Integer[] mImageIds = { R.drawable.gallery_photo_1, R.drawable.gallery_photo_2, R.drawable.gallery_photo_3, R.drawable.gallery_photo_4, R.drawable.gallery_photo_5, R.drawable.gallery_photo_6, R.drawable.gallery_photo_7, R.drawable.gallery_photo_8 }; } }

main.xml

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

attrs.xml

<?xml version="1.0" encoding="utf-8"?> <resources> <!-- These are the attributes that we want to retrieve from the theme in view/Gallery1.java --> <declare-styleable name="Gallery1"> <attr name="android:galleryItemBackground" /> </declare-styleable> </resources>

strings.xml

<?xml version="1.0" encoding="utf-8"?> <resources> <string name="gallery_2_text">Testing</string> <string name="app_name">Gallery</string> </resources>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="cn.android.lyj" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="10" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:label="@string/app_name" android:name=".Activity_01" > <intent-filter > <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

二. 运行结果

运行后

点击第一幅图片后

长按出现上下文菜单

点击其中一项后