GeometryMath.java

package org.osmdroid.util;

import android.graphics.Point;
import android.graphics.Rect;

/**
 * 
 * @author Marc Kurtz
 * 
 */
public class GeometryMath
{
	public static final double DEG2RAD = (Math.PI / 180.0);
	public static final double RAD2DEG = (180.0 / Math.PI);

	public static final Rect getBoundingBoxForRotatatedRectangle(Rect rect, float angle, Rect reuse) {
		return getBoundingBoxForRotatatedRectangle(rect, rect.centerX(), rect.centerY(), angle,
				reuse);
	}

	public static final Rect getBoundingBoxForRotatatedRectangle(Rect rect, Point centerPoint,
			float angle, Rect reuse) {
		return getBoundingBoxForRotatatedRectangle(rect, centerPoint.x, centerPoint.y, angle, reuse);
	}

	public static final Rect getBoundingBoxForRotatatedRectangle(Rect rect, int centerX,
			int centerY, float angle, Rect reuse) {
		if (reuse == null)
			reuse = new Rect();

		double theta = angle * DEG2RAD;
		double sinTheta = Math.sin(theta);
		double cosTheta = Math.cos(theta);
		double dx1 = rect.left - centerX;
		double dy1 = rect.top - centerY;
		double newX1 = centerX - dx1 * cosTheta + dy1 * sinTheta;
		double newY1 = centerY - dx1 * sinTheta - dy1 * cosTheta;
		double dx2 = rect.right - centerX;
		double dy2 = rect.top - centerY;
		double newX2 = centerX - dx2 * cosTheta + dy2 * sinTheta;
		double newY2 = centerY - dx2 * sinTheta - dy2 * cosTheta;
		double dx3 = rect.left - centerX;
		double dy3 = rect.bottom - centerY;
		double newX3 = centerX - dx3 * cosTheta + dy3 * sinTheta;
		double newY3 = centerY - dx3 * sinTheta - dy3 * cosTheta;
		double dx4 = rect.right - centerX;
		double dy4 = rect.bottom - centerY;
		double newX4 = centerX - dx4 * cosTheta + dy4 * sinTheta;
		double newY4 = centerY - dx4 * sinTheta - dy4 * cosTheta;
		reuse.set((int) Min4(newX1, newX2, newX3, newX4), (int) Min4(newY1, newY2, newY3, newY4),
				(int) Max4(newX1, newX2, newX3, newX4), (int) Max4(newY1, newY2, newY3, newY4));

		return reuse;
	}

	private static double Min4(double a, double b, double c, double d) {
		return Math.floor(Math.min(Math.min(a, b), Math.min(c, d)));
	}

	private static double Max4(double a, double b, double c, double d) {
		return Math.ceil(Math.max(Math.max(a, b), Math.max(c, d)));
	}
}