windows not in focus

[Heinzzy]

OriginalGriff wrote:

Then you have a problem. all the Keyboard emulating BCRs I have seen read teh BC and just provide a datastream as if the barcode data had been typed by the user.

I feel it's all ok. User such as a cashier isn't supposed to use a keyboard very often. So we can redirect BC stream to the textbox. In the textbox handler we can validate BC/user input. For example - user always start typing session with "A" char, else it's BC's chars.

[MickCurley]

I can understand if you are developing a POS system you may want this input to be directed to the textbox. You could always try setting the KeyPreview to True on the Form. Then on the KeyPress you could try

    private void YourForm\_KeyPress(object sender, KeyPressEventArgs e)
    {
        ScannerFirstKeyValue = e.KeyChar.ToString();

        if (this.ActiveControl != this.YourTextBox)
        {
            YourTextBox.AppendText(ScannerFirstKeyValue);
        }
        this.ActiveControl = YourTextBox;
    }

This would ensure all input is placed in correct textbox. Remember if you have multiple textboxes this will be a problem!! Unless the BC Reader has some sort of prefix that can distinguish it from a keyboard.

Regards Mick Curley :)

[Luc Pattyn]

doesn't that prevent people from typing anything in any other Control? :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

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I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.

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[Heinzzy]

But we still can distinguish BC from user by using prefixes. What do you think?

[michaelgr1]

Hi, I need this thing only to read data from barcode reader. Is there a way so only data from it (COM1 port for example) will be insereted to that textbox or the clipboard even if the application is not in focus (in background)?

[wjp_auhtm]

I think that you need create a windows service. When the computer got data, the service app show the data on the form's textbox, even the form unfocused.

[michaelgr1]

OK how can i do it using my application?

[Heinzzy]

Although it's rather unwieldy task I guess I know a way to perform it. To interact with an application that is not in focus I recommend you to use windows application log. Create the window service to handle BC input and write it down to the Log. In the application - check the Log for new entries on timer event and if it exists put it into your textbox. So despite your application might be not in focuse it still can achieve data from BC.

[michaelgr1]

i think a better way is to create a windows service that will read the data from the Barcode reader and then put in in the clipboard. But i don't know how to create such service and how to read from this device (USB port)

[Heinzzy]

To capture Keyboard stream use hooks Read this http://msdn.microsoft.com/en-us/library/ms632589(VS.85).aspx[^] Simple example using System; using System.Collections.Generic; using System.Text; using System.Diagnostics; using System.Runtime.InteropServices; namespace hook { class Program { private const int WH_KEYBOARD_LL = 13; private const int WM_KEYDOWN = 0x0100; private static LowLevelKeyboardProc _proc = HookCallback; private static IntPtr _hookID = IntPtr.Zero; static void Main() { _hookID = SetHook(_proc); Application.Run(); UnhookWindowsHookEx(_hookID); } private static IntPtr SetHook(LowLevelKeyboardProc proc) { using (Process curProcess = Process.GetCurrentProcess()) using (ProcessModule curModule = curProcess.MainModule) { return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0); } } private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam); private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam) { if ((nCode >= 0) && (wParam == (IntPtr)WM_KEYDOWN)) { int vkCode = Marshal.ReadInt32(lParam); if (((Keys)vkCode == Keys.LWin) || ((Keys)vkCode == Keys.RWin)) { Console.WriteLine("{0} blocked!", (Keys)vkCode); return (IntPtr)1; } } return CallNextHookEx(_hookID, nCode, wParam, lParam); } [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern bool UnhookWindowsHookEx(IntPtr hhk); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]

[Heinzzy]

So, we have a result here. To accomplish the mission you should definitly create a service. With hooks! ;)

[michaelgr1]

how do i use this code? where do i put in? in the program.cs ? and is it a windows service?

[Ravi Bhavnani]

A Windows service almost never has access to the desktop.  See this[^] article. /ravi

My new year resolution: 2048 x 1536 Home | Articles | My .NET bits | Freeware ravib(at)ravib(dot)com

[wjp_auhtm]

Oh! I try to open a win app from a windows service, but I was failed. I consider that creating a socket connect between the windows service and the win app may be practicable. creating windows service like this. creating socket like this.

[wjp_auhtm]

Yes, it can not instantiation a win form and show it. But I think that the socket could connect the win service and win app.

[michaelgr1]

OK. But i have another question- If i create a windows service to manage the data from the barcode reader (the data will go to clipboard and then set focus to my application), How can i install this windows service on a user computer (without installutil etc.)?

[wjp_auhtm]

You could install the windows service like this, if u are using .Net FrameWork 3.5. I found that the file named "System.Configuration.Install.dll" in .Net 2.0 is different from the .Net 3.5's. There are some simple code.

using System.ServiceProcess;
using System.Configuration.Install;
using System.Collections;

        /// <summary>
        /// TODO: Is the service is existed and return true or false.
        /// </summary>
        /// <param name=" NameService ">Name of the windows service.</param>
        /// <returns>If the service is existed then return true,or return false.</returns>
        private bool isServiceIsExisted(string NameService) 
        {
            ServiceController\[\] services = ServiceController.GetServices();
            foreach (ServiceController s in services) 
            {
                if (s.ServiceName.ToLower() == NameService.ToLower()) 
                {
                    return true;
                }
            }
            return false;
        }

        /// <summary>
        /// TODO: Install windows service.
        /// </summary>
        /// <param name="stateSaver">Collection(default is Null)</param>
        /// <param name="filepath">Full path of the windows service file</param>
        private void InstallmyService(IDictionary stateSaver, string filepath)
        {
            AssemblyInstaller AssemblyInstaller1 = new AssemblyInstaller();
            AssemblyInstaller1.UseNewContext = true;
            AssemblyInstaller1.Path = filepath;
            AssemblyInstaller1.Install(stateSaver);
            AssemblyInstaller1.Commit(stateSaver);
            AssemblyInstaller1.Dispose();
        }
        /// <summary>
        /// TODO: Uninstall windows service.
        /// </summary>
        /// <param name="filepath">Full path of the windows service file</param>
        private void UnInstallmyService(string filepath)
        {
            AssemblyInstaller AssemblyInstaller1 = new AssemblyInstaller();
            AssemblyInstaller1.UseNewContext = true;
            AssemblyInstaller1.Path = filepath;
            AssemblyInstaller1.Uninstall(null);
            AssemblyInstaller1.Dispose();
        }

Good Luck!

[michaelgr1]

Will this code start the service too?

[wjp_auhtm]

If set the windows service autorun, when you restart computer, the service will start. Of course, you can start the service in manual like this.

        /// <summary>
        /// TODO: Start windows service.
        /// </summary>
        /// <param name="name">The name of windows service.</param>
        /// <returns>If success return true,or return false.;</returns>
        private bool StarmyService(string name)
        {
            ServiceController sc = new ServiceController(name);
            if (sc.Status == ServiceControllerStatus.Stopped || sc.Status == ServiceControllerStatus.StopPending
                    )
            {
                sc.Start();
                sc.WaitForStatus(ServiceControllerStatus.Running, new TimeSpan(0, 0, 10));
            }
            else
            {
            }
            sc.Close();
            return true;
        }

And stop the service like this

        /// <summary>
        /// TODO: Stop windows service.
        /// </summary>
        /// <param name="name">The name of windows service.</param>
        /// <returns>If success return true,or return false.;</returns>
        private bool StopmyService(string name)
        {
            ServiceController sc = new ServiceController(name);
            if (sc.Status == ServiceControllerStatus.Running ||
                sc.Status == ServiceControllerStatus.StartPending)
            {
                sc.Stop();
                sc.WaitForStatus(ServiceControllerStatus.Stopped, new TimeSpan(0, 0, 10));
            }
            else
            {
            }
            sc.Close();
            return true;
        }

[michaelgr1]

OK and how can i set the service to start automatically ? i mean in the service code. Also how can i check if the service is already running?