ImageShadow.java

package com.flounder.fishDiary.image;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;
import android.graphics.Shader.TileMode;

public class ImageShadow {

    public static Bitmap reflectImage(Bitmap bitmap) {

        // Gap between reflection and the original image
        final int reflectionGap = 4;

        int width = bitmap.getWidth();
        int height = bitmap.getHeight();

        // Flip on the Y axis
        Matrix matrix = new Matrix();
        matrix.preScale(1, -1);

        // Create a Bitmap with the flip matrix applied to it
        Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, height / 2,
                width, height / 2, matrix, false);

        // Create a new Bitmap with same width but taller to fit reflection
        Bitmap bitmapWithReflection = Bitmap.createBitmap(width, height
                + height / 2, Config.ARGB_8888);

        // Create a new Canvas with the bitmap for the image plus reflection
        Canvas canvas = new Canvas(bitmapWithReflection);

        // Draw the origin image
        canvas.drawBitmap(bitmap, 0, 0, null);
        // Draw the gap
        Paint defaultPaint = new Paint();
        canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
        // Draw the reflection
        canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);

        // Create a shader that is a linear gradient that covers the reflection
        Paint paint = new Paint();
        LinearGradient shader = new LinearGradient(0, height, 0,
                bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,
                0x00ffffff, TileMode.MIRROR);

        // Set the paint to use this shader
        paint.setShader(shader);
        // Set the Transfer mode to be porter duff and destination in
        paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
        // Draw a rectangle using the paint with linear gradient
        canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
                + reflectionGap, paint);
        return bitmapWithReflection;
    }
}