[android] Assert that two bitmaps are similar

assertBitmapsAreSimilar.java

public static void assertBitmapsAreSimilar(Bitmap expectedBitmap, Bitmap actualBitmap, double tolerance) {
	Bitmap reducedExpectedBitmap = Bitmap.createScaledBitmap(expectedBitmap, 32, 32, true);
	Bitmap reducedActualBitmap  = Bitmap.createScaledBitmap(actualBitmap, 32, 32, true);
		
	int cumulatedColorDistance = 0;
		
	for (int x = 0 ; x < reducedExpectedBitmap.getWidth() ; x++) {
		for (int y = 0 ; y<reducedExpectedBitmap.getHeight() ; y++) {
			int expectedColor = reducedExpectedBitmap.getPixel(x, y);
			int actualColor = reducedActualBitmap.getPixel(x, y);
			int expectedRed = Color.red(expectedColor);
			int actualRed = Color.red(actualColor);
			int expectedBlue = Color.blue(expectedColor);
			int actualBlue = Color.blue(actualColor);
			int expectedGreen = Color.green(expectedColor);
			int actualGreen = Color.green(actualColor);
			int colorDistance = Math.abs(expectedRed - actualRed) + Math.abs(expectedBlue - actualBlue) + Math.abs(expectedGreen - actualGreen);
			cumulatedColorDistance += colorDistance;
		}
	}
		
	double difference = 100.0 * cumulatedColorDistance / 3.0 / (32.0 * 32.0) / 255.0;
		
	if (difference > tolerance) {
		fail("Difference between the bitmaps: " + difference + "% (>" + tolerance + "%)");
	}
}