Java – Android flood filling algorithm

Who knows an iterative and effective flood filling algorithm?

Or is there a way to implement recursive filling algorithm without stack overflow error?

I tried a @ flood fill using a stack, but I couldn't find a way to process white and black images

Solution

Someone transplanted J. Dunlap's queue linear flood fill algorithm to Android here I've tried it and it's very fast

I modified the copyimage () method, which initially used a class named utilities not provided by the author

public class QueueLinearFloodFiller {

    protected Bitmap image = null;
    protected int[] tolerance = new int[] { 0,0 };
    protected int width = 0;
    protected int height = 0;
    protected int[] pixels = null;
    protected int fillColor = 0;
    protected int[] startColor = new int[] { 0,0 };
    protected boolean[] pixelsChecked;
    protected Queue<FloodFillRange> ranges;

    // Construct using an image and a copy will be made to fill into,// Construct with BufferedImage and flood fill will write directly to
    // provided BufferedImage
    public QueueLinearFloodFiller(Bitmap img) {
        copyImage(img);
    }

    public QueueLinearFloodFiller(Bitmap img,int targetColor,int newColor) {
        useImage(img);

        setFillColor(newColor);
        setTargetColor(targetColor);
    }

    public void setTargetColor(int targetColor) {
        startColor[0] = Color.red(targetColor);
        startColor[1] = Color.green(targetColor);
        startColor[2] = Color.blue(targetColor);
    }

    public int getFillColor() {
        return fillColor;
    }

    public void setFillColor(int value) {
        fillColor = value;
    }

    public int[] getTolerance() {
        return tolerance;
    }

    public void setTolerance(int[] value) {
        tolerance = value;
    }

    public void setTolerance(int value) {
        tolerance = new int[] { value,value,value };
    }

    public Bitmap getImage() {
        return image;
    }

    public void copyImage(Bitmap img) {
        // Copy data from provided Image to a BufferedImage to write flood fill
        // to,use getImage to retrieve
        // cache data in member variables to decrease overhead of property calls
        width = img.getWidth();
        height = img.getHeight();

        image = Bitmap.createBitmap(width,height,Bitmap.Config.RGB_565);
        Canvas canvas = new Canvas(image);
        canvas.drawBitmap(img,null);

        pixels = new int[width * height];

        image.getPixels(pixels,width,1,width - 1,height - 1);
    }

    public void useImage(Bitmap img) {
        // Use a pre-existing provided BufferedImage and write directly to it
        // cache data in member variables to decrease overhead of property calls
        width = img.getWidth();
        height = img.getHeight();
        image = img;

        pixels = new int[width * height];

        image.getPixels(pixels,height - 1);
    }

    protected void prepare() {
        // Called before starting flood-fill
        pixelsChecked = new boolean[pixels.length];
        ranges = new LinkedList<FloodFillRange>();
    }

    // Fills the specified point on the bitmap with the currently selected fill
    // color.
    // int x,int y: The starting coords for the fill
    public void floodFill(int x,int y) {
        // Setup
        prepare();

        if (startColor[0] == 0) {
            // ***Get starting color.
            int startPixel = pixels[(width * y) + x];
            startColor[0] = (startPixel >> 16) & 0xff;
            startColor[1] = (startPixel >> 8) & 0xff;
            startColor[2] = startPixel & 0xff;
        }

        // ***Do first call to floodfill.
        LinearFill(x,y);

        // ***Call floodfill routine while floodfill ranges still exist on the
        // queue
        FloodFillRange range;

        while (ranges.size() > 0) {
            // **Get Next Range Off the Queue
            range = ranges.remove();

            // **Check Above and Below Each Pixel in the Floodfill Range
            int downPxIdx = (width * (range.Y + 1)) + range.startX;
            int upPxIdx = (width * (range.Y - 1)) + range.startX;
            int upY = range.Y - 1;// so we can pass the y coord by ref
            int downY = range.Y + 1;

            for (int i = range.startX; i <= range.endX; i++) {
                // *Start Fill Upwards
                // if we're not above the top of the bitmap and the pixel above
                // this one is within the color tolerance
                if (range.Y > 0 && (!pixelsChecked[upPxIdx])
                        && CheckPixel(upPxIdx))
                    LinearFill(i,upY);

                // *Start Fill Downwards
                // if we're not below the bottom of the bitmap and the pixel
                // below this one is within the color tolerance
                if (range.Y < (height - 1) && (!pixelsChecked[downPxIdx])
                        && CheckPixel(downPxIdx))
                    LinearFill(i,downY);

                downPxIdx++;
                upPxIdx++;
            }
        }

        image.setPixels(pixels,height - 1);
    }

    // Finds the furthermost left and right boundaries of the fill area
    // on a given y coordinate,starting from a given x coordinate,filling as
    // it goes.
    // Adds the resulting horizontal range to the queue of floodfill ranges,// to be processed in the main loop.

    // int x,int y: The starting coords
    protected void LinearFill(int x,int y) {
        // ***Find Left Edge of Color Area
        int lFillLoc = x; // the location to check/fill on the left
        int pxIdx = (width * y) + x;

        while (true) {
            // **fill with the color
            pixels[pxIdx] = fillColor;

            // **indicate that this pixel has already been checked and filled
            pixelsChecked[pxIdx] = true;

            // **de-increment
            lFillLoc--; // de-increment counter
            pxIdx--; // de-increment pixel index

            // **exit loop if we're at edge of bitmap or color area
            if (lFillLoc < 0 || (pixelsChecked[pxIdx]) || !CheckPixel(pxIdx)) {
                break;
            }
        }

        lFillLoc++;

        // ***Find Right Edge of Color Area
        int rFillLoc = x; // the location to check/fill on the left

        pxIdx = (width * y) + x;

        while (true) {
            // **fill with the color
            pixels[pxIdx] = fillColor;

            // **indicate that this pixel has already been checked and filled
            pixelsChecked[pxIdx] = true;

            // **increment
            rFillLoc++; // increment counter
            pxIdx++; // increment pixel index

            // **exit loop if we're at edge of bitmap or color area
            if (rFillLoc >= width || pixelsChecked[pxIdx] || !CheckPixel(pxIdx)) {
                break;
            }
        }

        rFillLoc--;

        // add range to queue
        FloodFillRange r = new FloodFillRange(lFillLoc,rFillLoc,y);

        ranges.offer(r);
    }

    // Sees if a pixel is within the color tolerance range.
    protected boolean CheckPixel(int px) {
        int red = (pixels[px] >>> 16) & 0xff;
        int green = (pixels[px] >>> 8) & 0xff;
        int blue = pixels[px] & 0xff;

        return (red >= (startColor[0] - tolerance[0])
                && red <= (startColor[0] + tolerance[0])
                && green >= (startColor[1] - tolerance[1])
                && green <= (startColor[1] + tolerance[1])
                && blue >= (startColor[2] - tolerance[2]) && blue <= (startColor[2] + tolerance[2]));
    }

    // Represents a linear range to be filled and branched from.
    protected class FloodFillRange {
        public int startX;
        public int endX;
        public int Y;

        public FloodFillRange(int startX,int endX,int y) {
            this.startX = startX;
            this.endX = endX;
            this.Y = y;
        }
    }
}

If you don't want the UI to wait for the image to fill, you can also use threads

public class FloodFillThread extends Thread {
    ProgressDialog mProgressDialog;
    Bitmap mBitmap;
    int mTargetColor;
    int mNewColor;
    Point mPoint;
    Runnable mCallback;

    public FloodFillThread(ProgressDialog pd,Runnable callback,Bitmap bitmap,Point pt,int newColor) {
        mBitmap = bitmap;
        mPoint = pt;
        mTargetColor = targetColor;
        mNewColor = newColor;
        mProgressDialog = pd;
        mCallback = callback;
    }

    @Override
    public void run() {
        QueueLinearFloodFiller filler = new QueueLinearFloodFiller(mBitmap,mTargetColor,mNewColor);
        filler.setTolerance(10);
        filler.floodFill(mPoint.x,mPoint.y);

        handler.sendEmptyMessage(0);
    }

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            mProgressDialog.dismiss();
            mCallback.run();
        }
    };
}