I have a simple console app written in C#. I want to be able to detect arrow key presses, so I can allow the user to steer. How do I detect keydown/keyup events with a console app?
All my googling has led to info about windows Forms. I don't have a GUI. This is a console app (to control a robot over a serial port).
I have functions written to handle these events, but I have no idea how to register to actually receive the events:
private void myKeyDown(object sender, KeyEventArgs e)
{
switch (e.KeyCode)
{
case Keys.Left:
...
case Keys.Right:
...
case Keys.Up:
...
}
}
private void myKeyUp(object sender, KeyEventArgs e)
{
... pretty much the same as myKeyDown
}
This is probably a really basic question, but I'm fairly new to C#, and I've never needed to get this kind of input before.
Update: Many are suggesting I use System.Console.ReadKey(true).Key
. This will not help. I need to know the moment a key is held down, when it is released, with support for multiple keys to be held down simultaneously. Also, ReadKey is a blocking call -- which means that the program will stop and wait for a key to be pressed.
Update: It seems that the only viable way to do this is to use Windows Forms. This is annoying, as I cannot use it on a headless system. Requiring a Form GUI to receive keyboard input is ... stupid.
But anyway, for posterity, here's my solution. I created a new Form project in my .sln:
private void Form1_Load(object sender, EventArgs e)
{
try
{
this.KeyDown += new KeyEventHandler(Form1_KeyDown);
this.KeyUp += new KeyEventHandler(Form1_KeyUp);
}
catch (Exception exc)
{
...
}
}
void Form1_KeyDown(object sender, KeyEventArgs e)
{
switch (e.KeyCode)
{
// handle up/down/left/right
case Keys.Up:
case Keys.Left:
case Keys.Right:
case Keys.Down:
default: return; // ignore other keys
}
}
private void Form1_KeyUp(object sender, KeyEventArgs e)
{
// undo what was done by KeyDown
}
Note that if you hold down a key, KeyDown will be called numerous times, and KeyUp will only be called once (when you release it). So you need to handle repeated KeyDown calls gracefully.
A bit late now, but here's how to access keyboard state in a console application.
Note that it's not all managed code as it requires GetKeyState to be imported from User32.dll.
/// <summary>
/// Codes representing keyboard keys.
/// </summary>
/// <remarks>
/// Key code documentation:
/// http://msdn.microsoft.com/en-us/library/dd375731%28v=VS.85%29.aspx
/// </remarks>
internal enum KeyCode : int
{
/// <summary>
/// The left arrow key.
/// </summary>
Left = 0x25,
/// <summary>
/// The up arrow key.
/// </summary>
Up,
/// <summary>
/// The right arrow key.
/// </summary>
Right,
/// <summary>
/// The down arrow key.
/// </summary>
Down
}
/// <summary>
/// Provides keyboard access.
/// </summary>
internal static class NativeKeyboard
{
/// <summary>
/// A positional bit flag indicating the part of a key state denoting
/// key pressed.
/// </summary>
private const int KeyPressed = 0x8000;
/// <summary>
/// Returns a value indicating if a given key is pressed.
/// </summary>
/// <param name="key">The key to check.</param>
/// <returns>
/// <c>true</c> if the key is pressed, otherwise <c>false</c>.
/// </returns>
public static bool IsKeyDown(KeyCode key)
{
return (GetKeyState((int)key) & KeyPressed) != 0;
}
/// <summary>
/// Gets the key state of a key.
/// </summary>
/// <param name="key">Virtuak-key code for key.</param>
/// <returns>The state of the key.</returns>
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern short GetKeyState(int key);
}
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