图片左右滚动控件（带倒影）——重写Gallery

转http://blog.csdn.net/ryantang03/article/details/8053643

今天在网上找了些资料，做了一个图片左右滚动的Demo，类似幻灯片播放，同时，图片带倒影效果，运行效果如下图：

实现方式是重写Gallery，使用自定义的Gallery来实现这一效果，工程一共三个文件，一个Activity，一个自定义的Gallery，还有就是一个适配器ImageAdapter，直接上代码：

ScrollGallery.java

public class ScrollGallery extends Gallery {
    private Camera mCamera = new Camera();
    //左右图片倾斜的角度
    private int mMaxRotationAngle = 60;
    //背景区域大小
    private int mMaxZoom = -380;
    private int mCoveflowCenter;  

    public ScrollGallery(Context context) {
        super(context);
        this.setStaticTransformationsEnabled(true);
    }  

    public ScrollGallery(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.setStaticTransformationsEnabled(true);
    }  

    public ScrollGallery(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) {
        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
        // 在Y轴上移动，上下移动；X轴上左右移动。
        mCamera.translate(0.0f, 0.0f, 100.0f);
        if (rotation < mMaxRotationAngle) {
            float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));
            mCamera.translate(0.0f, 0.0f, zoomAmount);
        }
        // 在Y轴上旋转，竖向向里翻转。
        // 在X轴上旋转，则横向向里翻转。
        mCamera.rotateY(rotationAngle);
        mCamera.getMatrix(imageMatrix);
        imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));
        imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));
        mCamera.restore();
    }
}  

ImageAdapter.java

public class ImageAdapter extends BaseAdapter {
    //倒影的缩放比例
    private static final int REFLECTION = 5;  

    int mGalleryItemBackground;
    private Context mContext;
    private int[] mImageIds;
    private ImageView[] mImages;  

    public ImageAdapter(Context c, int[] ImageIds) {
        mContext = c;
        mImageIds = ImageIds;
        mImages = new ImageView[mImageIds.length];
    }  

    public boolean createReflectedImages() {
        final int reflectionGap = 5;
        int index = 0;
        for (int imageId : mImageIds) {
            Bitmap originalImage = BitmapFactory.decodeResource(
                    mContext.getResources(), imageId);
            int width = originalImage.getWidth();
            int height = originalImage.getHeight();
            Matrix matrix = new Matrix();
            matrix.preScale(1, -1);
            Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
                    height / 2, width, height / 2, matrix, false);
            Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
                    (height + height / REFLECTION), Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmapWithReflection);
            canvas.drawBitmap(originalImage, 0, 0, null);
            Paint deafaultPaint = new Paint();
            canvas.drawRect(0, height, width, height + reflectionGap,
                    deafaultPaint);
            canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
            Paint paint = new Paint();
            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 ScrollGallery.LayoutParams(180, 240));
            mImages[index++] = imageView;
        }
        return true;
    }  

    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)));
    }
}  

ScrollImageActivity.java

public class ScrollImageActivity extends Activity {
    /** Called when the activity is first created. */  

    private ScrollGallery galleryFlow = null;  

    int images[] = {R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,R.drawable.f};  

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);
        galleryFlow = (ScrollGallery) this.findViewById(R.id.gf_images);
        ImageAdapter adapter = new ImageAdapter(this, images);
        adapter.createReflectedImages();
        galleryFlow.setAdapter(adapter);
        galleryFlow.setSelection(1);
    }
}  

 

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >  

    <com.ryan.scrollimage.ScrollGallery
        android:id="@+id/gf_images"
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="1" />  

</LinearLayout>