java - 如何在Android中使用flood fill算法？

Question

我是 Android 编程的新手，最近尝试编写一个简单的应用程序，只是为了练习!在这一个中，我想在用户点击时为图像着色，但我不知道如何开始。我读过不同的主题，说要使用“洪水填充”算法。我在网上找到了它，但我不知道如何将它放入我的简单应用程序中。

我找到的代码:

private void FloodFill(Bitmap bmp, Point pt, int targetColor, int replacementColor) 
{
   Queue<Point> q = new LinkedList<Point>();
   q.add(pt);
   while (q.size() > 0) {
       Point n = q.poll();
       if (bmp.getPixel(n.x, n.y) != targetColor)
           continue;

    Point w = n, e = new Point(n.x + 1, n.y);

    while ((w.x > 0) && (bmp.getPixel(w.x, w.y) == targetColor)) {
        bmp.setPixel(w.x, w.y, replacementColor);
        if ((w.y > 0) && (bmp.getPixel(w.x, w.y - 1) == targetColor))
            q.add(new Point(w.x, w.y - 1));
        if ((w.y < bmp.getHeight() - 1) && (bmp.getPixel(w.x, w.y + 1) == targetColor))
            q.add(new Point(w.x, w.y + 1));

        w.x--;
    }

    while ((e.x < bmp.getWidth() - 1) && (bmp.getPixel(e.x, e.y) == targetColor)) {
        bmp.setPixel(e.x, e.y, replacementColor);
        if ((e.y > 0) && (bmp.getPixel(e.x, e.y - 1) == targetColor))
            q.add(new Point(e.x, e.y - 1));
        if ((e.y < bmp.getHeight() - 1) && (bmp.getPixel(e.x, e.y + 1) == targetColor))
            q.add(new Point(e.x, e.y + 1));

        e.x++;
    }
  }
}

我知道如何在用户手指触摸事件后在屏幕上画线，但我还想知道如何用某种颜色填充给定图像，例如这个:

A little lion!

我在堆栈溢出上看到了这些其他问题:

• First topic
• Second topic
• Third topic

这看起来很容易做到，但我做不到!你能给我举个小例子吗？我想知道如何设置 Canvas 、为图像着色以及如何设置。

Answer 1

android using flood fill algorithm getting out of memory exception .检查链接是否有示例。

你需要 x 和 y 的坐标，你可以使用 asynctask 来填充封闭区域。使用进度对话框，直到填充颜色用替换颜色填充封闭区域。

注意:我在为大型封闭区域着色时遇到了问题。花了很多时间。我不确定使用 asynctask 是否是最好的方式。我希望有人能澄清这部分

您可以根据需要修改以下内容。

final Point p1 = new Point();
p1.x=(int) x; //x co-ordinate where the user touches on the screen
p1.y=(int) y; //y co-ordinate where the user touches on the screen  

FloodFill f= new FloodFill(); 
f.floodFill(bmp,pt,targetColor,replacementColor);

用 FloodFill 算法填充封闭区域

    public class FloodFill {
public void floodFill(Bitmap  image, Point node, int targetColor,
        int replacementColor) {
    int width = image.getWidth();
    int height = image.getHeight();
    int target = targetColor;
    int replacement = replacementColor;
    if (target != replacement) {
        Queue<Point> queue = new LinkedList<Point>();
        do {
            int x = node.x;
            int y = node.y;
            while (x > 0 && image.getPixel(x - 1, y) == target) {
                x--;
            }
            boolean spanUp = false;
            boolean spanDown = false;
            while (x < width && image.getPixel(x, y) == target) {
                image.setPixel(x, y, replacement);
                if (!spanUp && y > 0 && image.getPixel(x, y - 1) == target) {
                    queue.add(new Point(x, y - 1));
                    spanUp = true;
                } else if (spanUp && y > 0
                        && image.getPixel(x, y - 1) != target) {
                    spanUp = false;
                }
                if (!spanDown && y < height - 1
                        && image.getPixel(x, y + 1) == target) {
                    queue.add(new Point(x, y + 1));
                    spanDown = true;
                } else if (spanDown && y < height - 1
                        && image.getPixel(x, y + 1) != target) {
                    spanDown = false;
                }
                x++;
            }
        } while ((node = queue.poll()) != null);
    }
}
}

编辑:

编辑 8-7-2014 :

填充一个小的封闭区域可以很好地使用上述洪水填充算法。然而，对于大面积，该算法运行缓慢并且消耗大量内存。最近我看到一篇使用 QueueLinear Flood Fill 的帖子，它比上面的快得多。

来源:

http://www.codeproject.com/Articles/16405/Queue-Linear-Flood-Fill-A-Fast-Flood-Fill-Algorith

代码:

public class QueueLinearFloodFiller {

    protected Bitmap image = null;
    protected int[] tolerance = new int[] { 0, 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, 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, 0, 0, null);

        pixels = new int[width * height];

        image.getPixels(pixels, 0, width, 1, 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, 0, width, 1, 1, width - 1, 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, 0, width, 1, 1, width - 1, 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;
        }
    }
}