package org.stevec.fractals; import java.awt.*; import java.awt.event.MouseEvent; import java.awt.image.BufferedImage; import java.lang.Math; import javax.swing.JApplet; import javax.swing.event.MouseInputAdapter; /** * @author stevec * This was one of my first Java applets. It looks like C code translated to Java, which * is what happened in my head in the course of developing it. It's not very object- * oriented. Oh, well. * * This class computes and draws the Mandelbrot set on an applet. By clicking and dragging * the mouse, a user can zoom in and examine different parts of the set. */ public class Mandelbrot extends JApplet { private static final long serialVersionUID = -7748976827770978468L; int _width, _height; int _clipX, _clipY, _clipW, _clipH; double minX, maxX, minY, maxY; int xDim, yDim; double aspectRatio; BufferedImage image; int startX, startY, lastX, lastY; boolean _drawSelection; Rectangle _selectionRect = new Rectangle(); public void init() { MyListener myListener = new MyListener(); addMouseListener(myListener); addMouseMotionListener(myListener); // // Initialize drawable parameters // _width = this.getSize().width; _height = this.getSize().height; xDim = _width; yDim = _height; image = new BufferedImage(xDim, yDim, BufferedImage.TYPE_INT_RGB); _clipX = 0; _clipY = 0; _clipW = xDim; _clipH = yDim; _selectionRect.x = 0; _selectionRect.y = 0; _selectionRect.width = xDim; _selectionRect.height = yDim; _drawSelection = false; aspectRatio = (double)xDim / (double)yDim; if (aspectRatio > 1) { minY = -1.6; maxY = 1.6; minX = -2.1 * aspectRatio; maxX = 1.1 * aspectRatio; } else { minX = -2.1; maxX = 1.1; minY = -1.6 / aspectRatio; maxY = 1.6 / aspectRatio; } createMandelbrotSet(minX, maxX, minY, maxY, 255); } public void paint(Graphics g) { g.drawImage(image, 0, 0, image.getWidth(), image.getHeight(), null); if (_drawSelection) { g.setColor(Color.yellow); g.drawRect(_selectionRect.x, _selectionRect.y, _selectionRect.width - 1, _selectionRect.height - 1); } } public void updateIt(int x, int y, int w, int h, boolean drO) { _clipX = x; _clipY = y; _clipW = w; _clipH = h; _drawSelection = drO; repaint(_clipX, _clipY, _clipW, _clipH); } public static int computeRGB(int red, int green, int blue) { int alpha = 255; int rgb = (alpha << 24) + (red << 16) + (green << 8) + blue; return rgb; } void colorImage(double[][] dImage, double xDim, double yDim, BufferedImage image) { int r, c; double minV, maxV; double scale; int p; int i, j, k; minV = maxV = dImage[0][0]; for (r = 0; r < yDim; r++) { for (c = 0; c < xDim; c++) { if (dImage[r][c] < minV) minV = dImage[r][c]; if (dImage[r][c] > maxV) maxV = dImage[r][c]; } } scale = (double)0xFFFFFF / (maxV - minV); for (r = 0; r < yDim; r++) { for (c = 0; c < xDim; c++) { int v; v = (int)(scale * dImage[r][c]); // between 0 and 0xFFFFFF i = 0; j = 0; k = 0; for (p = 1; p < 0x81; p = p << 1) { i += (v & 0x1) * p; v = v >> 1; j += (v & 0x1) * p; v = v >> 1; k += (v & 0x1) * p; v = v >> 1; } if (i < 0) i = 0; else if (i > 255) i = 255; if (j < 0) j = 0; else if (j > 255) j = 255; if (k < 0) k = 0; else if (k > 255) k = 255; int rgb = computeRGB(i, j, k); image.setRGB(c, r, rgb); } } } void createMandelbrotSet(double minX, double maxX, double minY, double maxY, int maxIterations) { double x, y, xx, oldxx, yy, a, b; int r, c; int i; double stepX, stepY, maxStep; int iters; double outOfBounds = 4.0; double[][] dImage = new double[yDim][xDim]; stepX = (maxX - minX) / (double)xDim; stepY = (maxY - minY) / (double)yDim; if (stepX > stepY) maxStep = stepX; else maxStep = stepY; iters = (int)((double)maxIterations * 0.08 / Math.sqrt(maxStep)); for (r = 0, y = minY; r < yDim; r++, y += stepY) { for (c = 0, x = minX; c < xDim; c++, x += stepX) { a = x; b = y; xx = a; yy = b; for (i = 1; i < iters; i++) { oldxx = xx; xx = xx * xx - yy * yy + a; yy = 2 * oldxx * yy + b; if (xx * xx + yy * yy > outOfBounds) break; } if (i == iters) i = 0; dImage[r][c] = (double)i; } } colorImage(dImage, xDim, yDim, image); } private class MyListener extends MouseInputAdapter { public void mouseDragged(MouseEvent e) { int x, y; int x1, x2, y1, y2; Rectangle cleanUp = new Rectangle(); // // Determine area to clean up (from last selection) // if (lastX > startX) { x1 = startX; x2 = lastX; } else { x1 = lastX; x2 = startX; } if (lastY > startY) { y1 = startY; y2 = lastY; } else { y1 = lastY; y2 = startY; } cleanUp.x = x1; cleanUp.y = y1; cleanUp.width = x2 - x1 + 1; cleanUp.height = y2 - y1 + 1; // // Determine new selection area // x = e.getX(); y = e.getY(); if (startX > x) { x1 = x; x2 = startX; } else { x1 = startX; x2 = x; } if (startY > y) { y1 = y; y2 = startY; } else { y1 = startY; y2 = y; } _selectionRect.x = x1; _selectionRect.y = y1; _selectionRect.width = x2 - x1 + 1; _selectionRect.height = y2 - y1 + 1; // // Total area to be repainted is the union of both previously // computed rectangles. // Rectangle totalRepaint = cleanUp.union(_selectionRect); updateIt(totalRepaint.x, totalRepaint.y, totalRepaint.width, totalRepaint.height, true); // // Update last position // lastX = x; lastY = y; } public void mouseReleased(MouseEvent e) { int x, y; double scaleX, scaleY; double scale; double diffX, diffY; x = e.getX(); y = e.getY(); if (x != startX && y != startY) { double endX, endY; if (x > startX) { endX = x; } else { endX = startX; startX = x; } if (y > startY) { endY = y; } else { endY = startY; } scaleX = (double)(endX - startX) / (double)xDim; scaleY = (double)(endY - startY) / (double)yDim; if (scaleX > scaleY) scale = scaleX; else scale = scaleY; diffX = (maxX - minX) * scale; diffY = (maxY - minY) * scale; minX = minX + (double)startX * (maxX - minX) / (double)xDim; maxY = maxY - (double)(yDim - endY) * (maxY - minY) / (double)yDim; maxX = minX + diffX; minY = maxY - diffY; createMandelbrotSet(minX, maxX, minY, maxY, 45); updateIt(0, 0, xDim, yDim, false); } } public void mousePressed(MouseEvent e) { startX = e.getX(); startY = e.getY(); lastX = startX; lastY = startY; } } }