Help me on my code

Question

Hi am new to java and swings.. I am just learing it now.. I have a code with me.. In this flood fills the whole background..As fas as i know its a transparent background. how can i make it as a solid one. How can i just fill the shape in which my mouse pointer is in..
   private void init() {
      clip = Toolkit.getDefaultToolkit().getSystemClipboard();
      this.zoom = 1;
       if (img == null) {
         this.setImageSize(Integer.parseInt(width), Integer.parseInt(height), false);
      this.setPreferredSize(new Dimension(img.getWidth() * zoom, img.getHeight() * zoom));
      this.addMouseListener(this);
      this.addMouseMotionListener(this);
      this.addMouseWheelListener(this);
      this.addKeyListener(this);
   private void setImageSize(int width, int height, boolean copyOld) {
      BufferedImage old = img;
      img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
      if (old != null && copyOld) {
         Graphics g = img.getGraphics();
         g.drawImage(old, 0, 0, null);
   public void paintComponent(Graphics g) {
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D) g;
      //zoomed bits
      g2.scale((double) zoom, (double) zoom);
      g2.setColor(bgColor);
      g2.fillRect(0, 0, img.getWidth(), img.getHeight());
      //unzoomded bits
      g2.drawImage(img, 0, 0, null);
      //displayObjects
      for (int i = 0; i < displayObjects.size(); i++) {
         JImagePaintObject paintObject = (JImagePaintObject) displayObjects.get(i);
         paintObject.addToGraphics(g2);
      //paint objects
      g2.drawImage(getObjectsImage(paintObjects), 0, 0, null);
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
      //paint highlight points for those objects selected
      if (currentMode == JImagePaintPanel.MODE_SELECT) {
         for (int o = 0; o < selectedObjects.size(); o++) {
            g2.setColor(Color.magenta);
            JImagePaintObject paintObject = (JImagePaintObject) selectedObjects.get(o);
            Point2D[] points = paintObject.getHighlightPoints();
            for (int i = 0; i < points.length; i++) {
               Point2D point = points;
g2.translate(paintObject.getTranslation()[0], paintObject.getTranslation()[1]);
g2.setStroke(new BasicStroke((float) (1.0 / zoom)));
RoundRectangle2D.Double rect = new RoundRectangle2D.Double((point.getX() - 2), (point.getY() - 2), 5, 5, 2, 2);
g2.draw(rect);
g2.translate(-paintObject.getTranslation()[0], -paintObject.getTranslation()[1]);
private void flood(Point initPoint, int rgb, int newRGB) {
ArrayList queue = new ArrayList();
boolean[][] seen = new boolean[img.getWidth()][img.getHeight()];
queue.add(initPoint);
while (queue.size() > 0) {
Point p = (Point) queue.remove(0);
int i = p.x;
int j = p.y;
if (seen[i][j]) {
continue;
seen[i][j] = true;
if (img.getRGB(i, j) == rgb) {
img.setRGB(i, j, newRGB);
img.getRaster().setSample(i, j, 3, 255);
if (i > 0 && !seen[i - 1][j]) {
queue.add(new Point(i - 1, j));
if (i < img.getWidth() - 1 && !seen[i + 1][j]) {
queue.add(new Point(i + 1, j));
if (j > 0 && !seen[i][j - 1]) {
queue.add(new Point(i, j - 1));
if (j < img.getHeight() - 1 && !seen[i][j + 1]) {
queue.add(new Point(i, j + 1));
public void mousePressed(MouseEvent e) {
this.requestFocus();
if ((e.getModifiersEx() & MouseEvent.BUTTON3_DOWN_MASK) == MouseEvent.BUTTON3_DOWN_MASK) {
dragDown = e.getPoint();
this.preCursor = this.getCursor();
this.setCursor(new Cursor(Cursor.HAND_CURSOR));
else if ((e.getModifiersEx() & MouseEvent.BUTTON1_DOWN_MASK) == MouseEvent.BUTTON1_DOWN_MASK) {
if (currentMode == JImagePaintPanel.MODE_FLOOD) {
int rgb = img.getRGB(e.getPoint().x / zoom, e.getPoint().y / zoom);
this.flood(new Point(e.getPoint().x / zoom, e.getPoint().y / zoom), rgb, this.getDrawColor().getRGB());
this.updatePanel();
this.updatePanel();

Answer 1

I've been over your code a few times now, and I don't see anything logically wrong with it. In fact it correctly filled in a few shapes I tested. Only performance changes can be made.
ArrayList queue = new ArrayList();
boolean[][] seen = new boolean[img.getWidth()][img.getHeight()];An ArrayList is probably the worst collection to choose for a Queue. In an ArrayList, everytime the head element is removed all the elements above it nead to be shifted. Any of the lists that implement the Queue interface will provide a much better alternative.
java.util.Queue queue = new java.util.LinkedList();or if you are using java 1.6
java.util.Queue queue = new java.util.ArrayDeque();The boolean array would also be better served as a java.util.Bitset which will take up 8 times less memory and even performs a little faster than the corresponding 2D boolean array. The reason it takes up 8 times less memory is because the JVM treats each boolean array as a byte array in the background.
BitSet seen = new BitSet(img.getWidth() * img.getHeight());
//and for pixel (x,y)
int bitIndex = y * img.getWidth() + x;
BitSet#set(bitIndex);
BitSet#get(bitIndex);
BitSet#clear(bitIndex);The algorithm can also be implemented so that a boolean array or BitSet is not needed. The [wikipedia entry on the subject|http://en.wikipedia.org/wiki/Flood_fill] is pretty good.
Here's sort of a generic one I came up. It uses the the scanline approach mentioned in the Wikipedia article. The speed of it is unimpressive (when compared to MS Paint). A faster implementation would be to avoid creating Point objects, and to avoid the use of getRGB(...) and setRGB(...) to manipulate pixel data (and instead move to a lower level like the raster or data buffer).
public static void floodFill(BufferedImage img,
        int x, int y, int newRGB) {
    int oldRGB = img.getRGB(x,y);
    if(oldRGB == newRGB) return;
    java.awt.Graphics2D g2 = img.createGraphics();
    g2.setColor(new java.awt.Color(newRGB));
    java.util.Deque<Point> stack =
            new java.util.ArrayDeque<Point>();
    stack.add(new Point(x,y));
    while(stack.size() > 0) {
        Point p = stack.pop();
        x = p.x; y = p.y;
        img.setRGB(x, y, newRGB);
        int x1 = x-1;
        while(x1 > 0 &&
                img.getRGB(x1, y) == oldRGB) {
            x1--;
        x1++;
        int x2 = x+1;
        while(x2 < img.getWidth() &&
                img.getRGB(x2, y) == oldRGB) {
            x2++;
        x2--;
        g2.drawLine(x1,y,x2,y);
        if(y > 0) {
            boolean inScanline = false;
            for(int i = x1; i <= x2; i++) {
                boolean isTargetColor = img.getRGB(i, y-1) == oldRGB;
                if(!inScanline && isTargetColor) {
                    stack.push(new Point(i,y-1));
                    inScanline = true;
                }else if (inScanline && !isTargetColor) {
                    inScanline = false;
        if(y < img.getHeight()-1) {
            boolean inScanline = false;
            for(int i = x1; i <= x2; i++) {
                boolean isTargetColor = img.getRGB(i, y+1) == oldRGB;
                if(!inScanline && isTargetColor) {
                    stack.push(new Point(i,y+1));
                    inScanline = true;
                }else if (inScanline && !isTargetColor) {
                    inScanline = false;
}