Arrow.java

/*
Copyright 2014 Google Inc. All rights reserved.

        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 fr.steren.cloudcup;

/**
 * Created by mirnabouchra on 11/21/14.
 */
import android.graphics.Path;
import android.graphics.Point;

public class Arrow {

    public static final float ARROW_HEAD_LENGTH_RATIO = 8.5f;

    private Point head;
    private Point tail;
    private Boolean curved;
    private Boolean animated;
    private String description;
    private Path path;

    public Arrow() {
        this.head = new Point(0,0);
        this.tail = new Point(0,0);
        this.curved = true;
        this.animated = true;
        this.description = "";
        this.path = new Path();
    }
    public void setHead(int x, int y){
        this.setHead(new Point(x,y));
    }
    public void setHead(Point point){
        this.head = point;
        this.generatePath();
    }
    public void setTail(Point point){
        this.tail = point;
        this.generatePath();
    }
    public void setTail(int x, int y){
        this.setTail(new Point(x,y));
    }
    public void setCurved(Boolean curved){
        this.curved = curved;
        this.generatePath();
    }
    public boolean getAnimated(){
        return this.animated;
    }
    public void setAnimated(boolean animated){
        this.animated = animated;
    }
    public void setAnimated(Boolean animated){
        this.animated = animated;
    }
    public void setDescription(String description){
        this.description = description;
    }
    private void generatePath(){
        Boolean shouldCurve = (head.x == tail.x || head.y == tail.y) ? false : this.curved;

        Path path = new Path();
        path.moveTo(this.tail.x,this.tail.y);
        if(shouldCurve) {
            path.quadTo(this.head.x,this.tail.y,this.tail.x,this.tail.y);
        }
        else {
            path.lineTo(this.head.x,this.head.y);
        }

        //Calculate Arrow Head
        Point A = shouldCurve ? new Point(this.head.x,this.tail.y) : this.tail;
        Point B = this.head;

        // Vector from A to B:
        Point AB = new Point(B.x - A.x, B.y - A.y);

        // Length of AB == distance from A to B:
        double d = Math.hypot(AB.x, AB.y);

        // Arrow size == distance from C to B.
        float arrowSize = getArrowHeadLength(d);

        // Vector from C to B:
        Point CB = new Point((int)(AB.x * arrowSize/d), (int)(AB.y * arrowSize/d));

        // Compute P and Q:
        Point P = new Point(B.x - CB.x - CB.y, B.y - CB.y + CB.x);
        Point Q = new Point(B.x - CB.x + CB.y, B.y - CB.y - CB.x);

        path.moveTo(this.head.x,this.head.y);
        path.lineTo(P.x,P.y);

        path.moveTo(this.head.x,this.head.y);
        path.lineTo(Q.x,Q.y);

        this.path = path;
    }
    private float getArrowHeadLength(double hypotenuse){
        return (float)(hypotenuse / ARROW_HEAD_LENGTH_RATIO);
    }
    public Path getPath(){
        return this.path;
    }
}