yacy_search_server/source/net/yacy/visualization/CircleTool.java

// CircleTool.java
// (C) 2007 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 22.05.2007 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
// 
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

package net.yacy.visualization;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;


public class CircleTool {  

    private static short[][] circles = new short[0][]; 
    
    private static short[] getCircleCoords(final short radius) {
        if ((radius - 1) < circles.length) return circles[radius - 1];
        
        // read some lines from known circles
        Set<String> crds = new HashSet<String>();
        //crds.add("0|0");
        String co;
        for (short i = (short) Math.max(0, circles.length - 2); i < circles.length; i++) {
            for (short j = 0; j < circles[i].length; j = (short) (j + 2)) {
                co = circles[i][j] + "|" + circles[i][j + 1];
                if (!(crds.contains(co))) crds.add(co);
            }
        }
        
        // copy old circles into new array
        short[][] newCircles = new short[radius][];
        System.arraycopy(circles, 0, newCircles, 0, circles.length);
        
        // compute more lines in new circles
        short x, y;
        List<short[]> crc;
        short r1;
        for (short r = (short) circles.length; r < newCircles.length; r++) {
            r1 = (short) (r + 1);
            crc = new ArrayList<short[]>();
            for (short a = 0; a < 2 * (r + 1); a++) {
                x = (short) (r1 * Math.cos(Math.PI * a / (4 * r1)));
                y = (short) (r1 * Math.sin(Math.PI * a / (4 * r1)));
                co = x + "|" + y;
                if (!(crds.contains(co))) {
                    crc.add(new short[]{x, y});
                    crds.add(co);
                }
                x = (short) (((double) r + 0.5) * Math.cos(Math.PI * a / (4 * r1)));
                y = (short) (((double) r + 0.5) * Math.sin(Math.PI * a / (4 * r1)));
                co = x + "|" + y;
                if (!(crds.contains(co))) {
                    crc.add(new short[]{x, y});
                    crds.add(co);
                }
            }
            // put coordinates into array
            //System.out.print("Radius " + r + " => " + crc.size() + " points: ");
            newCircles[r] = new short[2 * (crc.size() - 1)];
            short[] coords;
            short i2 = 0;
            for (short i = 0; i < crc.size() - 1; i++) {
                coords = crc.get(i);
                newCircles[r][i2++] = coords[0];
                newCircles[r][i2++] = coords[1];
                //System.out.print(circles[r][i][0] + "," +circles[r][i][1] + "; "); 
            }
            //System.out.println();
        }
        crc = null;
        crds = null;
        
        // move newCircles to circles array
        circles = newCircles;
        newCircles = null;
        
        // finally return wanted slice
        return circles[radius - 1];
    }
    
    public static void circle(final RasterPlotter matrix, final int xc, final int yc, final int radius, final int intensity) {
        if (radius == 0) {
            //matrix.plot(xc, yc, 100);
        } else {
            final short[] c = getCircleCoords((short) radius);
            short x, y;
            short limit = (short) (c.length / 2);
            short i2 = 0;
            for (short i = 0; i < limit; i++) {
                x = c[i2++];
                y = c[i2++];
                matrix.plot(xc + x    , yc - y - 1, intensity); // quadrant 1
                matrix.plot(xc - x + 1, yc - y - 1, intensity); // quadrant 2
                matrix.plot(xc + x    , yc + y    , intensity); // quadrant 4
                matrix.plot(xc - x + 1, yc + y    , intensity); // quadrant 3
            }
        }
    }
    
    public static void circle(final RasterPlotter matrix, final int xc, final int yc, final int radius, int fromArc, int toArc) {
        // draws only a part of a circle
        // arc is given in degree
        while (fromArc > 360) fromArc -=360;
        while (fromArc < 0  ) fromArc +=360;
        while (  toArc > 360)   toArc -=360;
        while (  toArc < 0  )   toArc +=360;
        if (radius == 0) {
            //matrix.plot(xc, yc, 100);
        } else {
            final short[] c = getCircleCoords((short) radius);
            final short q = (short) (c.length / 2);
            final short[] c4x = new short[q * 4];
            final short[] c4y = new short[q * 4];
            short a0, a1, a2, a3, b0, b1;
            for (short i = 0; i < q; i++) {
                b0 = (short) (2 * (i        ));
                b1 = (short) (2 * (q - 1 - i));
                a0 = c[b0    ];
                a1 = c[b0 + 1];
                a2 = c[b1    ];
                a3 = c[b1 + 1];
                c4x[i        ] =     a0    ; // quadrant 1
                c4y[i        ] = (short) (-a1 - 1);  // quadrant 1
                c4x[i +     q] = (short) (  1 - a2); // quadrant 2
                c4y[i +     q] = (short) (-a3 - 1);  // quadrant 2
                c4x[i + 2 * q] = (short) (  1 - a0); // quadrant 3
                c4y[i + 2 * q] =     a1    ; // quadrant 3
                c4x[i + 3 * q] =     a2    ; // quadrant 4
                c4y[i + 3 * q] =     a3    ; // quadrant 4
            }
            if (fromArc == toArc) {
                int i = q * 4 * fromArc / 360;
                matrix.plot(xc + c4x[i], yc + c4y[i], 100);
            } else if (fromArc > toArc) {
                // draw two parts
                for (int i = q * 4 * fromArc / 360; i < q * 4; i++) {
                    matrix.plot(xc + c4x[i], yc + c4y[i], 100);
                }
                for (int i = 0; i < q * 4 * toArc / 360; i++) {
                    matrix.plot(xc + c4x[i], yc + c4y[i], 100);
                }
            } else {
                // can be drawn in one part
                for (int i = q * 4 * fromArc / 360; i < q * 4 * toArc / 360; i++) {
                    matrix.plot(xc + c4x[i], yc + c4y[i], 100);
                }
            }
        }
    }
}