C# moving the mouse around realistically

Question

I am demoing a piece of software and want to build a mouse 'mover' function so that I can basically automate the process. I want to create realistic mouse movements but am having a bit of a mental block in the thought process. I can move a mouse around easily with c# but want it to be a bit more realistic than just the cursor appearing at a certain x, y, coordinates and then pressing a button.

I get the current position of the mouse and then get the end point. Calculate an arc between the two points, but then I need to calculate points along that arc so that I can add a timer event into that so that I can move from one point to the next, and then repeat this till I get to the target...

Anybody want to elaborate?

Thanks, R.

Answer 1

I converted the WindMouse function mentioned earlier into C# and it is actually pretty realistic. Note that this is just a rough sample and does not use wrappers for GetCursorPos and SetCursorPos. I will be using the Windows Input Simulator wrappers.

static class SampleMouseMove {

    static Random random = new Random();
    static int mouseSpeed = 15;

    static void Main(string[] args) {
        MoveMouse(0, 0, 0, 0);
    }

    static void MoveMouse(int x, int y, int rx, int ry) {
        Point c = new Point();
        GetCursorPos(out c);

        x += random.Next(rx);
        y += random.Next(ry);

        double randomSpeed = Math.Max((random.Next(mouseSpeed) / 2.0 + mouseSpeed) / 10.0, 0.1);

        WindMouse(c.X, c.Y, x, y, 9.0, 3.0, 10.0 / randomSpeed,
            15.0 / randomSpeed, 10.0 * randomSpeed, 10.0 * randomSpeed); 
    }

    static void WindMouse(double xs, double ys, double xe, double ye,
        double gravity, double wind, double minWait, double maxWait,
        double maxStep, double targetArea) {

        double dist, windX = 0, windY = 0, veloX = 0, veloY = 0, randomDist, veloMag, step;
        int oldX, oldY, newX = (int)Math.Round(xs), newY = (int)Math.Round(ys);

        double waitDiff = maxWait - minWait;
        double sqrt2 = Math.Sqrt(2.0);
        double sqrt3 = Math.Sqrt(3.0);
        double sqrt5 = Math.Sqrt(5.0);

        dist = Hypot(xe - xs, ye - ys);

        while (dist > 1.0) {

            wind = Math.Min(wind, dist);

            if (dist >= targetArea) {
                int w = random.Next((int)Math.Round(wind) * 2 + 1);
                windX = windX / sqrt3 + (w - wind) / sqrt5;
                windY = windY / sqrt3 + (w - wind) / sqrt5;
            }
            else {
                windX = windX / sqrt2;
                windY = windY / sqrt2;
                if (maxStep < 3)
                    maxStep = random.Next(3) + 3.0;
                else
                    maxStep = maxStep / sqrt5;
            }

            veloX += windX;
            veloY += windY;
            veloX = veloX + gravity * (xe - xs) / dist;
            veloY = veloY + gravity * (ye - ys) / dist;

            if (Hypot(veloX, veloY) > maxStep) {
                randomDist = maxStep / 2.0 + random.Next((int)Math.Round(maxStep) / 2);
                veloMag = Hypot(veloX, veloY);
                veloX = (veloX / veloMag) * randomDist;
                veloY = (veloY / veloMag) * randomDist;
            }

            oldX = (int)Math.Round(xs);
            oldY = (int)Math.Round(ys);
            xs += veloX;
            ys += veloY;
            dist = Hypot(xe - xs, ye - ys);
            newX = (int)Math.Round(xs);
            newY = (int)Math.Round(ys);

            if (oldX != newX || oldY != newY)
                SetCursorPos(newX, newY);

            step = Hypot(xs - oldX, ys - oldY);
            int wait = (int)Math.Round(waitDiff * (step / maxStep) + minWait);
            Thread.Sleep(wait);
        }

        int endX = (int)Math.Round(xe);
        int endY = (int)Math.Round(ye);
        if (endX != newX || endY != newY)
            SetCursorPos(endX, endY);
    }

    static double Hypot(double dx, double dy) {
        return Math.Sqrt(dx * dx + dy * dy);
    }

    [DllImport("user32.dll")]
    static extern bool SetCursorPos(int X, int Y);

    [DllImport("user32.dll")]
    public static extern bool GetCursorPos(out Point p);
}

Answer 2

I tried the arc calculation method, turned out to be far to complex and, in the end, it didn't look realistic. Straight lines look much more human, as JP suggests in his comment.

This is a function I wrote to calculate a linear mouse movement. Should be pretty self-explanatory. GetCursorPosition() and SetCursorPosition(Point) are wrappers around the win32 functions GetCursorPos and SetCursorPos.

As far as the math goes - technically, this is called Linear Interpolation of a line segment.

public void LinearSmoothMove(Point newPosition, int steps) {
    Point start = GetCursorPosition();
    PointF iterPoint = start;

    // Find the slope of the line segment defined by start and newPosition
    PointF slope = new PointF(newPosition.X - start.X, newPosition.Y - start.Y);

    // Divide by the number of steps
    slope.X = slope.X / steps;
    slope.Y = slope.Y / steps;

    // Move the mouse to each iterative point.
    for (int i = 0; i < steps; i++)
    {
        iterPoint = new PointF(iterPoint.X + slope.X, iterPoint.Y + slope.Y);
        SetCursorPosition(Point.Round(iterPoint));
        Thread.Sleep(MouseEventDelayMS);
    }

    // Move the mouse to the final destination.
    SetCursorPosition(newPosition);
}