MathUtils.java

/*
 * Copyright (c) 2012 Jason Polites Licensed under the Apache License, Version
 * 2.0 (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law
 * or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package com.tweetlanes.android.core.widget.gestureimageview;

import android.graphics.PointF;
import android.util.FloatMath;
import android.view.MotionEvent;

class MathUtils {

    public static float distance(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return FloatMath.sqrt(x * x + y * y);
    }

    public static float distance(PointF p1, PointF p2) {
        float x = p1.x - p2.x;
        float y = p1.y - p2.y;
        return FloatMath.sqrt(x * x + y * y);
    }

    public static float distance(float x1, float y1, float x2, float y2) {
        float x = x1 - x2;
        float y = y1 - y2;
        return FloatMath.sqrt(x * x + y * y);
    }

    public static void midpoint(MotionEvent event, PointF point) {
        float x1 = event.getX(0);
        float y1 = event.getY(0);
        float x2 = event.getX(1);
        float y2 = event.getY(1);
        midpoint(x1, y1, x2, y2, point);
    }

    private static void midpoint(float x1, float y1, float x2, float y2,
                                 PointF point) {
        point.x = (x1 + x2) / 2.0f;
        point.y = (y1 + y2) / 2.0f;
    }

    /**
     * Rotates p1 around p2 by angle degrees.
     *
     * @param p1
     * @param p2
     * @param angle
     */
    public static void rotate(PointF p1, PointF p2, float angle) {
        float px = p1.x;
        float py = p1.y;
        float ox = p2.x;
        float oy = p2.y;
        p1.x = (FloatMath.cos(angle) * (px - ox) - FloatMath.sin(angle)
                * (py - oy) + ox);
        p1.y = (FloatMath.sin(angle) * (px - ox) + FloatMath.cos(angle)
                * (py - oy) + oy);
    }

    public static float angle(PointF p1, PointF p2) {
        return angle(p1.x, p1.y, p2.x, p2.y);
    }

    private static float angle(float x1, float y1, float x2, float y2) {
        return (float) Math.atan2(y2 - y1, x2 - x1);
    }
}