Gui helper class to help position elements on the screen.

GuiHelper.java

import net.minecraft.client.MainWindow;

public class GuiHelper {

	public static final int DEFAULT_WINDOW_WIDTH = 427;
	public static final int DEFAULT_WINDOW_HEIGHT = 240;

	public static class Coordinates {

		public final int x;
		public final int y;

		public Coordinates(int x, int y) {
			this.x = x; this.y = y;
		}
	}

	/**
	 * Returns a set of {@code Coordinates} for a {@code GUI} element with the given width
	 * and position on the {@code y} axis in the main window.
	 *
	 * @param width size of the element along the {@code x} axis.
	 * @param y position on the {@code y} axis (from bottom).
	 * @param window instance of Minecraft {@code MainWindow}.
	 */
	public static Coordinates getCenteredPosition(int width, int y, MainWindow window) {

		int coordX = window.getScaledWidth() / 2 - width / 2;
		int coordY = window.getScaledHeight() - y;

		return new Coordinates(coordX, coordY);
	}

	/**
	 * Returns a set of {@code Coordinates} for a {@code GUI} element with the given
	 * position in the default window size coordinate grid. This way of resolving
	 * position should work for any set of given coordinates whether you want to
	 * center an element or have a free form position.
	 *
	 * @param x initial position of element along {@code x} axis.
	 * @param y initial position of element along {@code y} axis.
	 * @param window instance of Minecraft {@code MainWindow}.
	 */
	public static Coordinates getScaledPosition(int x, int y, MainWindow window) {

		int coordX = window.getScaledWidth() / 2 - (DEFAULT_WINDOW_WIDTH - x) + DEFAULT_WINDOW_WIDTH / 2;
		int coordY = window.getScaledHeight() - (DEFAULT_WINDOW_HEIGHT - y);

		return new Coordinates(coordX, coordY);
	}
}