XNA - Keyboard text input

Question

Okay, so basically I want to be able to retrieve keyboard text. Like entering text into a text field or something. I\'m only writing my game for windows. I\'ve disregarded u

Answer 1

Maybe I'm not understanding the question, but why can't you use the XNA Keyboard and KeyboardState classes?

Answer 2

This page is on top of google result about WM_CHAR interception in xna, so i leave here some note. Maybe this will be useful for other (if they will be able to understand my English =)) ).

I try code with windowshook from Sekhat, but seems there should be WH_GETMESSAGE passed to SetWindowsHookEx instead Win32.HookType.WH_CALLWNDPROC (only with WH_GETMESSAGE code lparaw will point to Win32.Message ).

Also there is sometime duplicated messages (with wparam 0). (look here - http://msdn.microsoft.com/en-us/library/ms644981%28v=VS.85%29.aspx something about PM_NOREMOVE/PM_REMOVE in WPARAM )

When i add something like this

    if (nCode >= 0 && wParam == 1)
    {
        Win32.TranslateMessage(ref lParam); 
        WndProc(ref lParam);
    }

wm_keypress wm_char duplication stopped (i supose 1 is PM_NOREMOVE or PM_REMOVE).

P.S. nuclex variant now show 404 page, but can be viewed with webarchive. nuclex variant works, but it cause broken mouseWheel processing from native XNA MouseState (on XNA 3.1) =(

Answer 3

Here's a simple way, IMO, to have the space, back, A-Z and then the special chars !,@,#,$,%,^,&,*,(,). (Note, you need to import System.Linq) Here are the fields:

Keys[] keys;
bool[] IskeyUp;
string[] SC = { ")" , "!", "@", "#", "$", "%", "^", "&", "*", "("};//special characters

Constructor:

keys = new Keys[38];
Keys[] tempkeys;
tempkeys = Enum.GetValues(typeof(Keys)).Cast<Keys>().ToArray<Keys>();
int j = 0;
for (int i = 0; i < tempkeys.Length; i++)
{
    if (i == 1 || i == 11 || (i > 26 && i < 63))//get the keys listed above as well as A-Z
    {
        keys[j] = tempkeys[i];//fill our key array
        j++;
    }
}
IskeyUp = new bool[keys.Length]; //boolean for each key to make the user have to release the key before adding to the string
for (int i = 0; i < keys.Length; i++)
    IskeyUp[i] = true;

And Finally, the update method:

string result = "";

public override void Update(GameTime gameTime)
{
    KeyboardState state = Keyboard.GetState();
    int i = 0;
    foreach (Keys key in keys)
    {
        if (state.IsKeyDown(key))
        {
            if (IskeyUp[i])
            {
                if (key == Keys.Back && result != "") result = result.Remove(result.Length - 1);
                if (key == Keys.Space) result += " ";
                if (i > 1 && i < 12)
                {
                    if (state.IsKeyDown(Keys.RightShift) || state.IsKeyDown(Keys.LeftShift))
                        result += SC[i - 2];//if shift is down, and a number is pressed, using the special key
                    else result += key.ToString()[1];
                }
                if (i > 11 && i < 38)
                {
                    if (state.IsKeyDown(Keys.RightShift) || state.IsKeyDown(Keys.LeftShift))
                       result += key.ToString();
                    else result += key.ToString().ToLower(); //return the lowercase char is shift is up.
                }
            }
            IskeyUp[i] = false; //make sure we know the key is pressed
        }
        else if (state.IsKeyUp(key)) IskeyUp[i] = true;
        i++;
    }
    base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);
}

Hopefull this well help. I personally thought it was easier to use than the hooks, and this also can easily be modified for special results (such as shuffling the keys).

Answer 4

I used the solution from this gamedev.net post and it works great :)

Answer 5

For adding a windows hook in XNA

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Reflection;

/* Author: Sekhat
 * 
 * License: Public Domain.
 * 
 * Usage:
 *
 * Inherit from this class, and override the WndProc function in your derived class, 
 * in which you handle your windows messages.
 * 
 * To start recieving the message, create an instance of your derived class, passing in the
 * window handle of the window you want to listen for messages for.
 * 
 * in XNA: this would be the Game.Window.Handle property
 * in Winforms Form.Handle property
 */

namespace WindowsHookExample
{
    public abstract class WindowsHook : IDisposable
    {
        IntPtr hHook;
        IntPtr hWnd;
        // Stored here to stop it from getting garbage collected
        Win32.WndProcDelegate wndProcDelegate;

        public WindowsHook(IntPtr hWnd)
        {
            this.hWnd = hWnd;

            wndProcDelegate = WndProcHook;

            CreateHook();
        }

        ~WindowsHook()
        {
            Dispose(false);
        }

        private void CreateHook()
        {

            uint threadId = Win32.GetWindowThreadProcessId(hWnd, IntPtr.Zero);

            hHook = Win32.SetWindowsHookEx(Win32.HookType.WH_CALLWNDPROC, wndProcDelegate, IntPtr.Zero, threadId);

        }

        private int WndProcHook(int nCode, IntPtr wParam, ref Win32.Message lParam)
        {
            if (nCode >= 0)
            {
                Win32.TranslateMessage(ref lParam); // You may want to remove this line, if you find your not quite getting the right messages through. This is here so that WM_CHAR is correctly called when a key is pressed.
                WndProc(ref lParam);
            }

            return Win32.CallNextHookEx(hHook, nCode, wParam, ref lParam);
        }

        protected abstract void WndProc(ref Win32.Message message);

        #region Interop Stuff
        // I say thankya to P/Invoke.net.
        // Contains all the Win32 functions I need to deal with
        protected static class Win32
        {
            public enum HookType : int
            {
                WH_JOURNALRECORD = 0,
                WH_JOURNALPLAYBACK = 1,
                WH_KEYBOARD = 2,
                WH_GETMESSAGE = 3,
                WH_CALLWNDPROC = 4,
                WH_CBT = 5,
                WH_SYSMSGFILTER = 6,
                WH_MOUSE = 7,
                WH_HARDWARE = 8,
                WH_DEBUG = 9,
                WH_SHELL = 10,
                WH_FOREGROUNDIDLE = 11,
                WH_CALLWNDPROCRET = 12,
                WH_KEYBOARD_LL = 13,
                WH_MOUSE_LL = 14
            }

            public struct Message
            {
                public IntPtr lparam;
                public IntPtr wparam;
                public uint msg;
                public IntPtr hWnd;
            }

            /// <summary>
            ///  Defines the windows proc delegate to pass into the windows hook
            /// </summary>                  
            public delegate int WndProcDelegate(int nCode, IntPtr wParam, ref Message m);

            [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
            public static extern IntPtr SetWindowsHookEx(HookType hook, WndProcDelegate callback,
                IntPtr hMod, uint dwThreadId);

            [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
            public static extern bool UnhookWindowsHookEx(IntPtr hhk);

            [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
            public static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, ref Message m);

            [DllImport("coredll.dll", SetLastError = true)]
            public static extern IntPtr GetModuleHandle(string module);

            [DllImport("user32.dll", EntryPoint = "TranslateMessage")]
            public extern static bool TranslateMessage(ref Message m);

            [DllImport("user32.dll")]
            public extern static uint GetWindowThreadProcessId(IntPtr window, IntPtr module);
        }
        #endregion

        #region IDisposable Members

        public void Dispose()
        {
            Dispose(true);
        }

        private void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Free managed resources here
            }
            // Free unmanaged resources here
            if (hHook != IntPtr.Zero)
            {
                Win32.UnhookWindowsHookEx(hHook);
            }
        }

        #endregion
    }
}