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Posted 15 Nov 2006

Queue-Linear Flood Fill: A Fast Flood Fill Algorithm

, 15 Nov 2006
A super-fast flood fill algorithm and implementation, plus helpful optimization tips for image processing.
using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Diagnostics;

namespace FloodFill2
    /// <summary>
    /// </summary>
    /// <param name="x"></param>
    /// <param name="y"></param>
    public delegate void UpdateScreenDelegate(ref int x, ref int y);

    /// <summary>
    /// The base class that the flood fill algorithms inherit from. Implements the
    /// basic flood filler functionality that is the same across all algorithms.
    /// </summary>
    public abstract class AbstractFloodFiller

        protected EditableBitmap bitmap;
        protected byte[] tolerance = new byte[] { 25, 25, 25 };
        protected Color fillColor = Color.Magenta;
        protected bool fillDiagonally = false;
        protected bool slow = false;

        //cached bitmap properties
        protected int bitmapWidth = 0;
        protected int bitmapHeight = 0;
        protected int bitmapStride = 0;
        protected int bitmapPixelFormatSize = 0;
        protected byte[] bitmapBits = null;

        //internal int timeBenchmark = 0;
        internal Stopwatch watch = new Stopwatch();
        internal UpdateScreenDelegate UpdateScreen;

        //internal, initialized per fill
        //protected BitArray pixelsChecked;
        protected bool[] pixelsChecked;
        protected byte[] byteFillColor;
        protected byte[] startColor;
        //protected int stride;

        public AbstractFloodFiller()


        public AbstractFloodFiller(AbstractFloodFiller configSource)
            if (configSource != null)
                this.Bitmap = configSource.Bitmap;
                this.FillColor = configSource.FillColor;
                this.FillDiagonally = configSource.FillDiagonally;
                this.Slow = configSource.Slow;
                this.Tolerance = configSource.Tolerance;

        public bool Slow
            get { return slow; }
            set { slow = value; }

        public Color FillColor
            get { return fillColor; }
            set { fillColor = value; }

        public bool FillDiagonally
            get { return fillDiagonally; }
            set { fillDiagonally = value; }

        public byte[] Tolerance
            get { return tolerance; }
            set { tolerance = value; }

        public EditableBitmap Bitmap
            get { return bitmap; }
                bitmap = value;

        public abstract void FloodFill(Point pt);

        protected void PrepareForFloodFill(Point pt)
            //cache data in member variables to decrease overhead of property calls
            //this is especially important with Width and Height, as they call
            //GdipGetImageWidth() and GdipGetImageHeight() respectively in gdiplus.dll - 
            //which means major overhead.
            byteFillColor = new byte[] { fillColor.B, fillColor.G, fillColor.R };
            bitmapBits = bitmap.Bits;
            bitmapWidth = bitmap.Bitmap.Width;
            bitmapHeight = bitmap.Bitmap.Height;

            pixelsChecked = new bool[bitmapBits.Length / bitmapPixelFormatSize];

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About the Author

J. Dunlap
Web Developer
United States United States
My main goal as a developer is to improve the way software is designed, and how it interacts with the user. I like designing software best, but I also like coding and documentation. I especially like to work with user interfaces and graphics.

I have extensive knowledge of the .NET Framework, and like to delve into its internals. I specialize in working with and MyXaml. I also like to work with ASP.NET, AJAX, and DHTML.

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