Android控件Gallery 3D效果

1.扩展Gallery：
public class GalleryFlow extends Gallery {
    private Camera mCamera = new Camera();//相机类
    private int mMaxRotationAngle = 60;//最大转动角度
    private int mMaxZoom = -300;////最大缩放值
    private int mCoveflowCenter;//半径值
    public GalleryFlow(Context context) {
        super(context);
        //支持转换 ,执行getChildStaticTransformation方法
        this.setStaticTransformationsEnabled(true);
    }
    public GalleryFlow(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.setStaticTransformationsEnabled(true);
    }
    public GalleryFlow(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.setStaticTransformationsEnabled(true);
    }
    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) {
        System.out.println("view left :"+view.getLeft());
        System.out.println("view width :"+view.getWidth());
        return view.getLeft() + view.getWidth() / 2;
    }
    
    
   //控制gallery中每个图片的旋转(重写的gallery中方法)
    protected boolean getChildStaticTransformation(View child, Transformation t) {  
        //取得当前子view的半径值
        final int childCenter = getCenterOfView(child);
        System.out.println("childCenter："+childCenter);
        final int childWidth = child.getWidth();
        //旋转角度
        int rotationAngle = 0;
        //重置转换状态
        t.clear();
        //设置转换类型
        t.setTransformationType(Transformation.TYPE_MATRIX);
        //如果图片位于中心位置不需要进行旋转
        if (childCenter == mCoveflowCenter) {
            transformImageBitmap((ImageView) child, t, 0);
        } else {
            //根据图片在gallery中的位置来计算图片的旋转角度
            rotationAngle = (int) (((float) (mCoveflowCenter - childCenter) / childWidth) * mMaxRotationAngle);
            System.out.println("rotationAngle:" +rotationAngle);
            //如果旋转角度绝对值大于最大旋转角度返回（-mMaxRotationAngle或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) {
        //对效果进行保存
        mCamera.save();
        final Matrix imageMatrix = t.getMatrix();
        //图片高度
        final int imageHeight = child.getLayoutParams().height;
        //图片宽度
        final int imageWidth = child.getLayoutParams().width;
        
        //返回旋转角度的绝对值
        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();
    }
}

2.填充图片容器(BaseAdapter):
public class ImageAdapter extends BaseAdapter {
    int mGalleryItemBackground;
    private Context mContext;
    private Integer[] mImageIds;
    private ImageView[] mImages;
    
    public ImageAdapter(Context c, Integer[] ImageIds) {
     mContext = c;
     mImageIds = ImageIds;
     mImages = new ImageView[mImageIds.length];
    }
    /**
     * 创建倒影效果
     * @return
     */
    public boolean createReflectedImages() {
     //倒影图和原图之间的距离
     final int reflectionGap = 4;
     int index = 0;
     for (int imageId : mImageIds) {
      //返回原图解码之后的bitmap对象
      Bitmap originalImage = BitmapFactory.decodeResource(mContext.getResources(), imageId);
      int width = originalImage.getWidth();
      int height = originalImage.getHeight();
      //创建矩阵对象
      Matrix matrix = new Matrix();
      
      //指定一个角度以0,0为坐标进行旋转
      // matrix.setRotate(30);
      
      //指定矩阵(x轴不变，y轴相反)
      matrix.preScale(1, -1);
      
      //将矩阵应用到该原图之中，返回一个宽度不变，高度为原图1/2的倒影位图
      Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
        height/2, width, height/2, matrix, false);
      
      //创建一个宽度不变，高度为原图+倒影图高度的位图
      Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
        (height + height / 2), Config.ARGB_8888);
      
      //将上面创建的位图初始化到画布
      Canvas canvas = new Canvas(bitmapWithReflection);
      canvas.drawBitmap(originalImage, 0, 0, null);
      
      Paint deafaultPaint = new Paint(); 
      deafaultPaint.setAntiAlias(false);
//    canvas.drawRect(0, height, width, height + reflectionGap,deafaultPaint);
      canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
      Paint paint = new Paint();
      paint.setAntiAlias(false);
       
      /**
       * 参数一:为渐变起初点坐标x位置，
       * 参数二:为y轴位置，
       * 参数三和四:分辨对应渐变终点，
       * 最后参数为平铺方式，
       * 这里设置为镜像Gradient是基于Shader类，所以我们通过Paint的setShader方法来设置这个渐变
       */
      LinearGradient shader = new LinearGradient(0,originalImage.getHeight(), 0,
              bitmapWithReflection.getHeight() + reflectionGap,0x70ffffff, 0x00ffffff, TileMode.MIRROR);
      //设置阴影
      paint.setShader(shader);
      paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.DST_IN));
      //用已经定义好的画笔构建一个矩形阴影渐变效果
      canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()+ reflectionGap, paint);
      
      //创建一个ImageView用来显示已经画好的bitmapWithReflection
      ImageView imageView = new ImageView(mContext);
      imageView.setImageBitmap(bitmapWithReflection);
      //设置imageView大小 ，也就是最终显示的图片大小
      imageView.setLayoutParams(new GalleryFlow.LayoutParams(300, 400));
      //imageView.setScaleType(ScaleType.MATRIX);
      mImages[index++] = imageView;
     }
     return true;
    }
    @SuppressWarnings("unused")
    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) {
        return mImages[position];
    }
    public float getScale(boolean focused, int offset) {
        return Math.max(0, 1.0f / (float) Math.pow(2, Math.abs(offset)));
    }
   }

3.创建Activity:
public class Gallery3DActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        
        setContentView(R.layout.layout_gallery);
        
        Integer[] images = { R.drawable.img0001, R.drawable.img0030,
                R.drawable.img0100, R.drawable.img0130, R.drawable.img0200,
                R.drawable.img0230,  R.drawable.img0330,R.drawable.img0354 };
        
        ImageAdapter adapter = new ImageAdapter(this, images);
        adapter.createReflectedImages();//创建倒影效果
        GalleryFlow galleryFlow = (GalleryFlow) this.findViewById(R.id.Gallery01);
        galleryFlow.setFadingEdgeLength(0);
        galleryFlow.setSpacing(-100); //图片之间的间距
        galleryFlow.setAdapter(adapter);
        
        galleryFlow.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                Toast.makeText(getApplicationContext(), String.valueOf(position), Toast.LENGTH_SHORT).show();
            }
            
        });
        galleryFlow.setSelection(4);
    }
}