Android Gallery图片显示和文字提示及Menu 菜单

Gallery组件主要用于横向显示图像列表，不过按常规做法。Gallery组件只能有限地显示指定的图像。也就是说，如果为Gallery组件指定了10张图像，那么当Gallery组件显示到第10张时，就不会再继续显示了。

代码里带注释，欢迎相互讨论

 

 

 

 

Layout里的main.xml文件：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="@drawable/background_port" > <ImageButton android:src="@drawable/login"android:layout_width="fill_parent"android:layout_height="wrap_content"android:id="@+id/login"android:background="#0000"/><com.king.showgallery.GameGallery android:id="@+id/imgGallery"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_centerHorizontal="true"android:layout_alignParentBottom="true"/></RelativeLayout> 

res/menu/menu.xml文件：

<?xml version="1.0" encoding="UTF-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android"><item android:id="@+id/menu_update" android:title="程序升级" android:icon="@drawable/icon_appupdate"/><item android:id="@+id/menu_download" android:title="下载中心" android:icon="@drawable/icon_download_center"/><item android:id="@+id/menu_feedback" android:title="用户反馈" android:icon="@drawable/icon_feedback"/><item android:id="@+id/menu_recommend" android:title="好友推荐" android:icon="@drawable/icon_recommend"/><item android:id="@+id/menu_about" android:title="关于我们" android:icon="@drawable/icon_about"/></menu> 

<item android:id="@+id/menu_about" android:title="关于我们" android:icon="@drawable/icon_about"/>

id标签，title是当前菜单的描述，icon是当前菜单的图片

package com.king.showgallery;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.Window;import android.view.WindowManager;import android.widget.AdapterView;import android.widget.TextView;import android.widget.Toast;import android.widget.AdapterView.OnItemClickListener;public class GalleryActivity extends MenuActivity {//imgList里装载需要显示的图片private Integer[] imgList={R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1,R.drawable.tab_selected_1};private Toast toast;public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //设置全屏 requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); setContentView(R.layout.main); ImageAdapter adapter = new ImageAdapter(this, imgList); adapter.createReflectedImages(); GameGallery gameGallery = (GameGallery) findViewById(R.id.imgGallery); gameGallery.setAdapter(adapter); gameGallery.setOnItemClickListener(new OnItemClickListener() { //AdapterView<?> arg0代表向spinner中加载的一系列字符串或其它事物，是一个适配器，是字符串和Spinner之间的桥梁！而View代表Spinner，int arg2代表ItemId, long arg3代表Item的position！ public void onItemClick(AdapterView<?> arg0, View view, int position, long arg3) { switch (position) {case 0://点击每个图片，根据图片的position，显示不同的内容toast.makeText(GalleryActivity.this, "this is zero", Toast.LENGTH_SHORT).show();break;case 1:toast.makeText(GalleryActivity.this, "this is one", Toast.LENGTH_SHORT).show();break;case 2:toast.makeText(GalleryActivity.this, "this is two", Toast.LENGTH_SHORT).show();break;case 3:toast.makeText(GalleryActivity.this, "this is three", Toast.LENGTH_SHORT).show();break;case 4://程序退出事件Intent startMain = new Intent(Intent.ACTION_MAIN);startMain.addCategory(Intent.CATEGORY_HOME);startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);startActivity(startMain);System.exit(0);break;case 5:toast.makeText(GalleryActivity.this, "this is five", Toast.LENGTH_SHORT).show();break;case 6:toast.makeText(GalleryActivity.this, "this is six", Toast.LENGTH_SHORT).show();break;case 7:toast.makeText(GalleryActivity.this, "this is seven", Toast.LENGTH_SHORT).show();break;default:break;} }}); }} 

对于Android开发我们可以做的尽量MVC化，UI界面和Code逻辑代码分离方式，除了常规的Activity布局可以用xml实现外，菜单Menu也可以通过MenuInflater来映射一个布局文件，相关的创建菜单方法有些不同。

package com.king.showgallery;import android.app.Activity;import android.content.Context;import android.os.Handler;import android.util.AttributeSet;import android.view.InflateException;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuInflater;import android.view.MenuItem;import android.view.View;import android.widget.Toast;public class MenuActivity extends Activity{public boolean onCreateOptionsMenu(Menu menu){super.onCreateOptionsMenu(menu);//MenuInflater 是用来解析定义在menu 目录下的菜单布局文件MenuInflater inflater=new MenuInflater(getApplicationContext());inflater.inflate(R.menu.menu, menu);return true;}public boolean onOptionsItemSelected(MenuItem item){String info="";switch (item.getItemId()) {case R.id.menu_about://点击当前菜单后显示效果info="isabout";break;case R.id.menu_download:info="isdownload";break;case R.id.menu_feedback:info="isfeedback";break;case R.id.menu_recommend:info="isrecommend";break;case R.id.menu_update:info="isupdate";break;default:info="null";break;}Toast toast=Toast.makeText(this, info, Toast.LENGTH_SHORT);toast.show();return super.onOptionsItemSelected(item);}protected void setMenuBackground(){MenuActivity.this.getLayoutInflater().setFactory(new android.view.LayoutInflater.Factory() {@Overridepublic View onCreateView(String name, Context context, AttributeSet attrs) {if(name.equalsIgnoreCase("com.android.internal.view.menu.IconMenuItemView")){try{LayoutInflater f=getLayoutInflater();final View view=f.createView(name, null, attrs);new Handler().post(new Runnable(){public void run(){view.setBackgroundResource(R.drawable.menu_background);}});return view;}catch(InflateException e){e.printStackTrace();}catch(ClassNotFoundException e){e.printStackTrace();}}return null;}});}} 

package com.king.showgallery;import android.content.Context;import android.graphics.Camera;import android.graphics.Matrix;import android.util.AttributeSet;import android.view.View;import android.view.animation.Transformation;import android.widget.Gallery;import android.widget.ImageView;public class GameGallery extends Gallery{public GameGallery(Context context){super(context);this.setStaticTransformationsEnabled(true);}public GameGallery(Context context,AttributeSet attrs){super(context,attrs);this.setStaticTransformationsEnabled(true);}public GameGallery(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);this.setStaticTransformationsEnabled(true);}//mCamera是用来做类3D效果处理,比如z轴方向上的平移,绕y轴的旋转等private Camera mCamera = new Camera();//mMaxRotationAngle是图片绕y轴最大旋转角度,也就是屏幕最边上那两张图片的旋转角度 private int mMaxRotationAngle = 60; //mMaxZoom是图片在z轴平移的距离,视觉上看起来就是放大缩小的效果. private int mMaxZoom = -120; private int mCoveflowCenter; public int getMaxRotationAngle() { return mMaxRotationAngle; } public void setMaxRotationAngle(int maxRotationAngle) { mMaxRotationAngle = maxRotationAngle; } public int getMaxZoom() { return mMaxZoom; } public void setMaxZoom(int maxZoom) { mMaxZoom = maxZoom; } private int getCenterOfCoverflow() { return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft(); } private static int getCenterOfView(View view) { return view.getLeft() + view.getWidth() / 2; } protected boolean getChildStaticTransformation(View child, Transformation t) { final int childCenter = getCenterOfView(child); final int childWidth = child.getWidth(); int rotationAngle = 0; t.clear(); t.setTransformationType(Transformation.TYPE_MATRIX); if (childCenter == mCoveflowCenter) { transformImageBitmap((ImageView) child, t, 0); } else { rotationAngle = (int) (((float) (mCoveflowCenter - childCenter) / childWidth) * mMaxRotationAngle); if (Math.abs(rotationAngle) > mMaxRotationAngle) { rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle; } transformImageBitmap((ImageView) child, t, rotationAngle); } return true; } protected void onSizeChanged(int w, int h, int oldw, int oldh) { mCoveflowCenter = getCenterOfCoverflow(); super.onSizeChanged(w, h, oldw, oldh); } private void transformImageBitmap(ImageView child, Transformation t, int rotationAngle) { mCamera.save(); final Matrix imageMatrix = t.getMatrix(); final int imageHeight = child.getLayoutParams().height; final int imageWidth = child.getLayoutParams().width; final int rotation = Math.abs(rotationAngle); // 在Z轴上正向移动camera的视角，实际效果为放大图片。 // 如果在Y轴上移动，则图片上下移动；X轴上对应图片左右移动。 mCamera.translate(0.0f, 0.0f, 100.0f); // As the angle of the view gets less, zoom in if (rotation < mMaxRotationAngle) { float zoomAmount = (float) (mMaxZoom + (rotation * 1.5)); mCamera.translate(0.0f, 0.0f, zoomAmount); } // 在Y轴上旋转，对应图片竖向向里翻转。 // 如果在X轴上旋转，则对应图片横向向里翻转。 mCamera.rotateY(rotationAngle); mCamera.getMatrix(imageMatrix); imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2)); imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2)); mCamera.restore(); }} 

package com.king.showgallery;import android.content.Context;import android.content.res.Resources;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PorterDuff.Mode;import android.graphics.PorterDuffXfermode;import android.graphics.Shader.TileMode;import android.graphics.Typeface;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.ImageView.ScaleType;public class ImageAdapter extends BaseAdapter{private Context mContext;private Integer[] mImageIds;private ImageView[] mImages;private String[] strings;private int width,height;//图片上的提示信息private String[] textList={"功能说明","项目说明","玩法说明","软件说明","退出","程序更新","兑奖","查询"};public ImageAdapter(Context c, Integer[] ImageIds) {mContext = c;mImageIds = ImageIds;mImages = new ImageView[mImageIds.length];}public boolean createReflectedImages() {final int reflectionGap = 4;int index = 0;for (int imageId : mImageIds) {Bitmap originalImage = BitmapFactory.decodeResource(mContext.getResources(), imageId);width = originalImage.getWidth();height = originalImage.getHeight();Matrix matrix = new Matrix();//matrix.setRotate(30);matrix.preScale(1, -1);Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,height / 2, width, height / 2, matrix, false);Bitmap bitmapWithReflection = Bitmap.createBitmap(width,(height + height / 2), Config.ARGB_8888);Canvas canvas = new Canvas(bitmapWithReflection);canvas.drawBitmap(originalImage, 0, 0, null);Paint deafaultPaint = new Paint();deafaultPaint.setAntiAlias(true);canvas.drawRect(0, height, width, height + reflectionGap,deafaultPaint);canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);Paint paint = new Paint();paint.setAntiAlias(true);LinearGradient shader = new LinearGradient(0,originalImage.getHeight(), 0,bitmapWithReflection.getHeight() + reflectionGap,0x70ffffff, 0x00ffffff, TileMode.CLAMP);paint.setShader(shader);paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()+ reflectionGap, paint);ImageView imageView = new ImageView(mContext);imageView.setImageBitmap(bitmapWithReflection);imageView.setLayoutParams(new GameGallery.LayoutParams(180, 240));mImages[index++] = imageView;}return true;}private Resources getResources() {return null;}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) {//给图片添加文字提示信息Bitmap newb = Bitmap.createBitmap( width,height, Config.ARGB_8888 ); Canvas canvasTemp = new Canvas( newb ); canvasTemp.drawColor(Color.alpha(0)); Paint p = new Paint(); String familyName = "宋体"; Typeface font = Typeface.create(familyName, Typeface.BOLD); p.setColor(Color.WHITE); p.setTypeface(font); p.setTextSize(30); canvasTemp.drawText(textList[position], 40,80, p); Drawable drawable = new BitmapDrawable(newb); mImages[position].setBackgroundDrawable(drawable); return mImages[position];}public float getScale(boolean focused, int offset) {return Math.max(0, 1.0f / (float) Math.pow(2, Math.abs(offset)));}} 

在ImageAdapter类中有两个非常重要的方法：getCount和getView。其中getCount方法用于返回图像总数，要注意的是，这个总数不能大于图像的实际数（可以小于图像的实际数），否则会抛出越界异常。当Gallery组件要显示某一个图像时，就会调用getView方法，并将当前的图像索引（position参数）传入该方法。一般getView方法用于返回每一个显示图像的组件（ImageView对象）。从这一点可以看出，Gallery组件是即时显示图像的，而不是一下将所有的图像都显示出来。在getView方法中除了创建了ImageView对象，还用从resIds数组中获得了相应的图像资源ID来设置在ImageView中显示的图像。最后还设置了Gallery组件的背景显示风格。

在ImageAdapter里给图片添加文字信息，注意

1.Bitmap，可以来自资源/文件，也可以在程序中创建，实际上的功能相当于图片的存储空间； 

2.Canvas，紧密与Bitmap联系，把Bitmap比喻内容的话，那么Canvas就是提供了众多方法操作Bitamp的平台； 

3.Paint，与Canvas紧密联系，是"画板"上的笔刷工具，也用于设置View控件上的样式； 

4.Drawable，如果说前三者是看不见地在内存中画图，那么Drawable就是把前三者绘图结果表现出来的接口。Drawable多个子类，例如：位图(BitmapDrawable)、图形(ShapeDrawable)、图层(LayerDrawable)等。