C＃如果立即按下更多键，如何不停止其他功能？

Question

I know the title was little unclear but i will explain. My Example: when i press 'D' my object will move to right, same for 'A' just move to left, but when i press 'Space' while holding 'A'/'D',the object will just o the function of the 'Space'.

if (e.KeyCode == Keys.A)
        {
            ply.Left -= 3;
        }

        if (e.KeyCode == Keys.D)
        {
            ply.Left += 3;
        }

        if (e.KeyCode == Keys.Space) {
            ply.Top -= 100;
        }

Answer 1

You can track the state of multiple keys through the use of both KeyUp and KeyDown by use of a HashSet<Keys> :

private HashSet<Keys> _keys = new HashSet<Keys>();

public void Control_KeyDown(object sender, KeyEventArgs e)
{
    _keys.Add(e.KeyCode);
}
public void Control_KeyUp(object sender, KeyEventArgs e)
{
    _keys.Remove(e.KeyCode);
}

public bool IsKeyDown(Keys keyCode)
{
    return _keys.Contains(keyCode);
}

Now, whenever you want to check to see if a key is down, just do:

if(IsKeyDown(Keys.A))
{
    ply.Left -= 3;
}

---

Keep in mind that if you just check key states in one of the key events, you will probably have issues with not detecting repeats properly. If you really want to handle this properly, you should use a Timer with a fairly small Interval that periodically polls with IsKeyDown and handles all your input.

With a Timer named timer1 that has an interval of 100 , you can handle all your input like this, and have fairly responsive input to the full range of keys supported by your hardware.

private void timer1_Tick(object sender, EventArgs e)
{
    if (IsKeyDown(Keys.A))
    {
        ply.Left -= 3;
    }
    if (IsKeyDown(Keys.S))
    {
        ply.Top += 3;
    }
    if (IsKeyDown(Keys.D))
    {
        ply.Left += 3;
    }
    if (IsKeyDown(Keys.W))
    {
        ply.Top -= 3;
    }
}

Answer 2

As Bradley said, you could save all key events to a keystate cache.

This could look something like this pseudo code:

Event KeyDown(e) -> keystate[e.KeyCode] = true
Event KeyUp(e)   -> keystate[e.KeyCode] = false

That way, you should always know every state.