Reflection Effect

BitmapHelper.java

public class BitmapHelper {
//gapRatio：間距的比例
//reflectRatio：鏡像的比例
public static Bitmap reflection(Bitmap src, float gapRatio, float reflectRatio) {
    int origWidth = src.getWidth();
    int origHeight = src.getHeight();
    int gapHeight = Float.valueOf(origHeight * gapRatio).intValue();
    int reflectHeight = Float.valueOf(origHeight * reflectRatio).intValue();
    
    //統一色彩定義，讓圖片色盤不會跑掉。不然jpg沒有alpha channel會很怪。
    //畫上原本的圖像
    Bitmap result = Bitmap.createBitmap(origWidth, origHeight + gapHeight + reflectHeight, Config.ARGB_8888);
    Canvas canvas = new Canvas(result);
    canvas.drawBitmap(src, 0, 0, null);
    
    //畫上鏡射的圖
    Matrix matrix = new Matrix();
    matrix.postScale(1, -1);
    Bitmap reflect = Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), matrix, true);
    canvas.drawBitmap(reflect, 0, origHeight + gapHeight, null);
    reflect.recycle();
    
    //替鏡射的圖加上漸透明的漸層
    Paint paint = new Paint();
    LinearGradient shader = new LinearGradient(0, origHeight, 0, result.getHeight(), 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
    paint.setShader(shader);
    paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
    canvas.drawRect(0, origHeight, origWidth, result.getHeight(), paint);
    
    return result;
}
}