Question

Okay so I’m trying to make a little gag program that will “run away” from the mouse.

So, to get the mouse coordinates for the whole screen and not just the form control I had to create a little helper:

static class MouseHelper
{
    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool GetCursorPos(ref Point pt);

    public static Point GetPosition()
    {
        Point w32Mouse = new Point();
        GetCursorPos(ref w32Mouse);
        return w32Mouse;
    }       
}

Now I thought I was going to use the MouseMove event… but that doesn’t work for outside the form control either so I have an auto-enabled timer on a 10ms loop called timerMouseMove.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private bool CollisionCheck()
    {
        Point win32Mouse = MouseHelper.GetPosition();

        if (win32Mouse.X <= Location.X || win32Mouse.X >= (Location.X + Width))
            return false;

        if (win32Mouse.Y <= Location.Y || win32Mouse.Y >= (Location.Y + Height))
            return false;

        return true;
    }

    private void timerMouseMove_Tick(object sender, EventArgs e)
    {
        if (CollisionCheck())
            Location = new Point(Location.X + 1, Location.Y + 1);
    }
}

So this works out nicely, at least I have the collision checking working and whatnot. But now, how should I go about figuring which side of the form the mouse has collided with, so that I can update its location to move in the opposite direction the mouse collides with it? And such halp

Answer 1

You’re capturing the mouse position over time, so you can infer the direction if you keep a “this position” and “last position”. You could even calculate the velocity, and move the form a greater distance if the mouse is moving faster.

Happy April Fool’s!