org.thole.hendrik.mandelbrot.gwt.client.impl.MandelBrotImpl.java Source code

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Here is the source code for org.thole.hendrik.mandelbrot.gwt.client.impl.MandelBrotImpl.java

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/*
 * Copyright (c) 1999/2000/2010 Manfred Thole, Hendrik Thole
 *
 * 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.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 */

package org.thole.hendrik.mandelbrot.gwt.client.impl;

import com.google.gwt.canvas.client.Canvas;
import com.google.gwt.canvas.dom.client.Context2d;
import com.google.gwt.canvas.dom.client.CssColor;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.RepeatingCommand;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Widget;

/**
 * 
 * @author Hendrik Thole, Manfred Thole
 * @date 20.07.2010
 *
 */
public class MandelBrotImpl {

    private int size_x = 250;
    private int size_y = 250;
    private final double xa = -2.25;
    private final double xe = 0.75;
    private final double ya = -1.5;
    private final double ye = 1.5;
    private final int itmax = 20;
    private int itmax13;
    private int itmax23;

    public Widget getMandel() {

        final int size_screen = Math.min(Window.getClientWidth(), Window.getClientHeight()) / 2;
        size_y = size_screen;
        size_x = size_screen;

        final Canvas canvas = Canvas.createIfSupported();
        canvas.setCoordinateSpaceHeight(size_y);
        canvas.setCoordinateSpaceWidth(size_y);
        canvas.setHeight(size_y + "px");
        canvas.setWidth(size_x + "px");
        final Context2d context = canvas.getContext2d();

        itmax13 = itmax * 1 / 3;
        itmax23 = itmax * 2 / 3;

        paintMandel(context);

        return canvas;
    }

    /**
     * Calculate the Set
     * @param canvas
     */
    private double ix, iy, zr, zi, zrq, ziq;
    private int it;

    private final void paintMandel(final Context2d context) {
        final double inx = (xe - xa) / size_x;
        final double iny = (ye - ya) / size_y;

        ix = xa;
        Scheduler.get().scheduleIncremental(new RepeatingCommand() {

            @Override
            public boolean execute() {
                if (ix <= xe) {
                    for (iy = ya; iy <= ye; iy += iny) {
                        it = 0;
                        zr = 0;
                        zi = 0;
                        do {
                            zrq = zr * zr;
                            ziq = zi * zi;
                            it++;
                            zi = 2 * zr * zi + iy;
                            zr = zrq - ziq + ix;
                        } while (zrq + ziq < 4 && it < itmax);

                        context.setFillStyle(it2C(it));
                        context.fillRect((ix - xa) / inx, (iy - ya) / iny, 1, 1);
                    }
                    ix += inx;
                    return true;
                }
                return false;
            }
        });

        //      for (ix = xa; ix <= xe; ix += inx) {
        //         for (iy = ya; iy <= ye; iy += iny) {
        //            it = 0;
        //            zr = 0;
        //            zi = 0;
        //            do {
        //               zrq = zr * zr;
        //               ziq = zi * zi;
        //               it++;
        //               zi = 2 * zr * zi + iy;
        //               zr = zrq - ziq + ix;
        //            } while (zrq + ziq < 4 && it < itmax);
        //
        //            context.setFillStyle(it2C(it));
        //            context.fillRect((ix-xa)/inx, (iy-ya)/iny, 1, 1);
        //         }
        //      }
    }

    /**
     * get the color.
     * @param it
     * @return Color
     */
    private final CssColor it2C(final int it) {
        if (it < itmax13) {
            return CssColor.make(it * 255 / itmax13, 0, 0);
        }
        if (it < itmax23) {
            return CssColor.make(0, (it - itmax13) * 255 / itmax13, 0);
        }
        return CssColor.make(0, 0, (it - itmax23) * 255 / itmax13);
    }
}