C# 魔棒工具-漫水填充算法优化

之前在魔棒工具的文章里写过一个漫水填充算法，实际使用效果并不好。这是因为算法将图片转为灰度再去与种子点的灰度比较。可以想象，这种做法是不合理的（虽然通常都是这么做）。比如两个视觉上相差很明显的颜色，其灰度值很有可能一样或者相差不大（无论你怎么修改RGB三者权重，终归会遇到这种情况）。所以最好是对颜色的ARGB四个分值分开进行比较，如果速度允许，可以计算方差；如果希望速度快一点，就直接计算差值。

1.按灰度检测

        /// <summary>///  漫水填充 FloodFill()按灰度检测，FloodFill_argb()按四通道分量检测/// </summary>/// <param name="src">原图</param>/// <param name="location">检测点</param>/// <param name="fillColor">填充颜色</param>/// <param name="threshould">阈值</param>/// <returns>填充图，非填充部分为默认值</returns>unsafe public Bitmap FloodFill(Bitmap src, Point location, Color fillColor, int threshould){try{Bitmap srcbmp = src;Color backColor = srcbmp.GetPixel(location.X, location.Y);Bitmap dstbmp = new Bitmap(src.Width, src.Height);int w = srcbmp.Width;int h = srcbmp.Height;Stack<Point> fillPoints = new Stack<Point>(w * h);System.Drawing.Imaging.BitmapData srcbmpData = srcbmp.LockBits(new Rectangle(0, 0, srcbmp.Width, srcbmp.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);System.Drawing.Imaging.BitmapData dstbmpData = dstbmp.LockBits(new Rectangle(0, 0, dstbmp.Width, dstbmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);int stride = srcbmpData.Stride;byte* srcbuf = (byte*)srcbmpData.Scan0.ToPointer();byte* dstbuf = (byte*)dstbmpData.Scan0.ToPointer();int  cr = backColor.R,  cg = backColor.G, cb = backColor.B, ca = backColor.A;byte fcr = fillColor.R, fcg = fillColor.G, fcb = fillColor.B;if (location.X < 0 || location.X >= w || location.Y < 0 || location.Y >= h) return null;fillPoints.Push(new Point(location.X, location.Y));int[,] mask = new int[w, h];while (fillPoints.Count > 0){Point p = fillPoints.Pop();mask[p.X, p.Y] = 1;dstbuf[3 * p.X + p.Y * stride] = fcb;dstbuf[3 * p.X + 1 + p.Y * stride] =  fcg;dstbuf[3 * p.X + 2 + p.Y * stride] =  fcr;if (p.X > 0 && (mask[p.X - 1, p.Y] != 1)&& Math.Abs(cb - srcbuf[3 * (p.X - 1) + p.Y * stride]) + Math.Abs(cg - srcbuf[3 * (p.X - 1) + 1 + p.Y * stride]) + Math.Abs(cr - srcbuf[3 * (p.X - 1) + 2 + p.Y * stride]) < threshould){dstbuf[3 * (p.X - 1) + p.Y * stride] = fcb;dstbuf[3 * (p.X - 1) + 1 + p.Y * stride] = fcg;dstbuf[3 * (p.X - 1) + 2 + p.Y * stride] = fcr;fillPoints.Push(new Point(p.X - 1, p.Y));mask[p.X - 1, p.Y] = 1;}if (p.X < w - 1 && (mask[p.X + 1, p.Y] != 1)&& Math.Abs(cb - srcbuf[3 * (p.X + 1) + p.Y * stride]) + Math.Abs(cg - srcbuf[3 * (p.X + 1) + 1 + p.Y * stride]) + Math.Abs(cr - srcbuf[3 * (p.X + 1) + 2+p.Y * stride]) < threshould ){dstbuf[3 * (p.X + 1) + p.Y * stride] = fcb;dstbuf[3 * (p.X + 1) + 1 + p.Y * stride] = fcg;dstbuf[3 * (p.X + 1) + 2 + p.Y * stride] = fcr;fillPoints.Push(new Point(p.X + 1, p.Y));mask[p.X + 1, p.Y] = 1;}if (p.Y > 0 && (mask[p.X, p.Y - 1] != 1)&& Math.Abs(cb - srcbuf[3 * p.X + (p.Y - 1) * stride]) + Math.Abs(cg - srcbuf[3 * p.X + 1 + (p.Y - 1) * stride]) + Math.Abs(cr - srcbuf[3 * p.X +2+ (p.Y - 1) * stride]) < threshould){dstbuf[3 * p.X + (p.Y - 1) * stride] = fcb;dstbuf[3 * p.X + 1 + (p.Y - 1) * stride] = fcg;dstbuf[3 * p.X + 2 + (p.Y - 1) * stride] = fcr;fillPoints.Push(new Point(p.X, p.Y - 1));mask[p.X, p.Y - 1] = 1;}if (p.Y < h - 1 && (mask[p.X, p.Y + 1] != 1)&& Math.Abs(cb - srcbuf[3 * p.X + (p.Y + 1) * stride]) + Math.Abs(cg - srcbuf[3 * p.X +1+ (p.Y + 1) * stride]) + Math.Abs(cr - srcbuf[3 * p.X +2+ (p.Y + 1) * stride]) < threshould){dstbuf[3 * p.X + (p.Y + 1) * stride] = fcb;dstbuf[3 * p.X + 1 + (p.Y + 1) * stride] = fcg;dstbuf[3 * p.X + 2 + (p.Y + 1) * stride] = fcr;fillPoints.Push(new Point(p.X, p.Y + 1));mask[p.X, p.Y + 1] = 1;}}fillPoints.Clear();srcbmp.UnlockBits(srcbmpData);dstbmp.UnlockBits(dstbmpData);return dstbmp;}catch (Exception exp){System.Windows.MessageBox.Show(exp.Message);return null;}}

        public int GetGray(byte r, byte g, byte b){return (int)(r * 77 + g * 151 + b * 28) >> 8;//按权重计算灰度值}

2.按颜色ARGB四分量检测

        unsafe public Bitmap FloodFill_argb(Bitmap src, Point location, Color fillColor, int threshould){try{Bitmap srcbmp = src;Color backColor = srcbmp.GetPixel(location.X, location.Y);Bitmap dstbmp = new Bitmap(src.Width, src.Height);int w = srcbmp.Width;int h = srcbmp.Height;Stack<Point> fillPoints = new Stack<Point>(w * h);System.Drawing.Imaging.BitmapData bmpData = srcbmp.LockBits(new Rectangle(0, 0, srcbmp.Width, srcbmp.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);System.Drawing.Imaging.BitmapData dstbmpData = dstbmp.LockBits(new Rectangle(0, 0, dstbmp.Width, dstbmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb);int stride = bmpData.Stride;int stridedst = dstbmpData.Stride;byte* srcbuf = (byte*)bmpData.Scan0.ToPointer();int* dstbuf = (int*)dstbmpData.Scan0.ToPointer();int cr = backColor.R, cg = backColor.G, cb = backColor.B, ca = backColor.A;byte fcr = fillColor.R, fcg = fillColor.G, fcb = fillColor.B;int fc = fillColor.ToArgb();if (location.X < 0 || location.X >= w || location.Y < 0 || location.Y >= h) return null;fillPoints.Push(new Point(location.X, location.Y));int[,] mask = new int[w, h];while (fillPoints.Count > 0){Point p = fillPoints.Pop();mask[p.X, p.Y] = 1;dstbuf[  p.X + p.Y * w] = fc;if (p.X > 0 && (mask[p.X - 1, p.Y] != 1)&& Math.Abs(cb - srcbuf[4 * (p.X - 1) + p.Y * stride]) + Math.Abs(cg - srcbuf[4 * (p.X - 1) + 1 + p.Y * stride]) + Math.Abs(cr - srcbuf[4 * (p.X - 1) + 2 + p.Y * stride]) < threshould&& Math.Abs(ca - srcbuf[4 * (p.X - 1) +3+ p.Y * stride]) < threshould/2){dstbuf[  (p.X - 1) + p.Y * w] = fc;fillPoints.Push(new Point(p.X - 1, p.Y));mask[p.X - 1, p.Y] = 1;}if (p.X < w - 1 && (mask[p.X + 1, p.Y] != 1)&& Math.Abs(cb - srcbuf[4 * (p.X + 1) + p.Y * stride]) + Math.Abs(cg - srcbuf[4 * (p.X + 1) + 1 + p.Y * stride]) + Math.Abs(cr - srcbuf[4 * (p.X + 1) + 2 + p.Y * stride]) < threshould&& Math.Abs(ca - srcbuf[4 * (p.X + 1) + 3 + p.Y * stride]) < threshould / 2){dstbuf[  (p.X + 1) + p.Y * w] = fc;fillPoints.Push(new Point(p.X + 1, p.Y));mask[p.X + 1, p.Y] = 1;}if (p.Y > 0 && (mask[p.X, p.Y - 1] != 1)&& Math.Abs(cb - srcbuf[4 * p.X + (p.Y - 1) * stride]) + Math.Abs(cg - srcbuf[4 * p.X + 1 + (p.Y - 1) * stride]) + Math.Abs(cr - srcbuf[4 * p.X + 2 + (p.Y - 1) * stride]) < threshould&& Math.Abs(ca - srcbuf[4 * p.X +3+ (p.Y - 1) * stride]) < threshould / 2){dstbuf[  p.X + (p.Y - 1) * w] = fc ;fillPoints.Push(new Point(p.X, p.Y - 1));mask[p.X, p.Y - 1] = 1;}if (p.Y < h - 1 && (mask[p.X, p.Y + 1] != 1)&& Math.Abs(cb - srcbuf[4 * p.X + (p.Y + 1) * stride]) + Math.Abs(cg - srcbuf[4 * p.X + 1 + (p.Y + 1) * stride]) + Math.Abs(cr - srcbuf[4 * p.X + 2 + (p.Y + 1) * stride]) < threshould&& Math.Abs(ca - srcbuf[4 * p.X +3+ (p.Y + 1) * stride]) < threshould /2){dstbuf[  p.X + (p.Y + 1) *w] = fc;fillPoints.Push(new Point(p.X, p.Y + 1));mask[p.X, p.Y + 1] = 1;}}fillPoints.Clear();srcbmp.UnlockBits(bmpData);dstbmp.UnlockBits(dstbmpData);return dstbmp;}catch (Exception exp){System.Windows.MessageBox.Show(exp.Message);return null;}}

3.测试

调整阈值，为了观察，把透明度也调整一下，点选花瓣

试一下透明区域

结果不错。