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>