Question

I need to calculate the distance between two places the mouse was clicked on the screen.

target(x & Y) & source(X & Y) are populated on the mouse move event (e.X & e.Y)

I have distance = Math.Sqrt(Math.Pow(targetX - sourceX, 2) + Math.Pow(targetY - sourceY, 2));

This gives me a result but if I’m honest I am not sure what unit the measurement is in or how to convert it. How can I convert that result in a meaningful result such as cm’s or inches? I’m guessing I will need to take the screen res into account?

Update
Im just killing time really. Not looking for an excellent solution just something that works. It will only last a day or two.

Here is the MoveMove event and the call made. Should have posted it all before to be clearer.

    private void HookManager_MouseMove(object sender, MouseEventArgs e)
    {

        labelMousePosition.Text = string.Format("x={0:0000}; y={1:0000}", e.X, e.Y);
        AddDistance(Convert.ToDouble(e.X), Convert.ToDouble(e.Y));
    }

    private void AddDistance(double targetX, double targetY)
    {
        if (sourceX != 0 && sourceY != 0)
        {
            double distance = Convert.ToDouble(lblDistanceTravelled.Text);
            distance =+ Math.Sqrt(Math.Pow(targetX - sourceX, 2) + Math.Pow(targetY - sourceY, 2));
            lblDistanceTravelled.Text = distance.ToString();
        }
        sourceX = targetX;
        sourceY = targetY;
    }

Answer 1

You can get the “current DPI” via

int currentDPI = 0;  
using (Graphics g = this.CreateGraphics())  
{  
    currentDPI = (int)g.DpiX;      
}

and then you can get

double distanceInInches = distance/*InPixels*/ / currentDPI;

However, the system’s DPI setting can’t really be relied upon to give a true conversion from pixel distances to on-screen-inch distances.