Method getColor

src/com/cloudream/ishow/util/BitmapUtils.java:805–845

(Bitmap bitmap, float x, float y)

	// bilinear interpolation
	public static int getColor(Bitmap bitmap, float x, float y)
	{
		assert (0 <= x && x < bitmap.getWidth());
		assert (0 <= y && y < bitmap.getHeight());
		// if(color == null || color.length < 3)
		// throw new IllegalArgumentException("color should be RGB");

		int x0 = (int) x;
		int y0 = (int) y;

		int c00 = bitmap.getPixel(x0, y0);
		int c01 = bitmap.getPixel(x0, y0 + 1);
		int c10 = bitmap.getPixel(x0 + 1, y0);
		int c11 = bitmap.getPixel(x0 + 1, y0 + 1);

		final float wx = x - x0, one_minus_wx = 1.0f - wx;
		final float wy = y - y0, one_minus_wy = 1.0f - wy;

		float r0 = Color.red(c00) * wx + Color.red(c01) * one_minus_wx;
		float r1 = Color.red(c10) * wx + Color.red(c11) * one_minus_wx;
		float r = r0 * wy + r1 * one_minus_wy;

		float g0 = Color.green(c00) * wx + Color.green(c01) * one_minus_wx;
		float g1 = Color.green(c10) * wx + Color.green(c11) * one_minus_wx;
		float g = g0 * wy + g1 * one_minus_wy;

		float b0 = Color.blue(c00) * wx + Color.blue(c01) * one_minus_wx;
		float b1 = Color.blue(c10) * wx + Color.blue(c11) * one_minus_wx;
		float b = b0 * wy + b1 * one_minus_wy;

		int red = Math.round(r), green = Math.round(g), blue = Math.round(b);
		if(bitmap.getConfig() == Bitmap.Config.RGB_565)
			return Color.rgb(red, green, blue);

		float a0 = Color.alpha(c00) * wx + Color.alpha(c01) * one_minus_wx;
		float a1 = Color.alpha(c10) * wx + Color.alpha(c11) * one_minus_wx;
		float a = a0 * wy + a1 * one_minus_wy;

		int alpha = Math.round(a);
		return Color.argb(red, green, blue, alpha);
	}

	/**
	 * http://stackoverflow.com/questions/3035692/how-to-convert-a-drawable-to-a-bitmap