Help with sendkey or postmessage - C# Discussion Boards

17-Feb-11 5:00

I am trying to send an "F2" keystroke to a window to refresh it.

I would like to send it to the window while it is minimized, I have Vista just as a little more information.

Here is the code I was testing on, it seems like PostMessage might be my best option, I am able to find the window handle through the code below, just not sure how to send an "F2" to it when minimized.

Thanks for reading.

private void button1_Click(object sender, EventArgs e)
{
    const int WM_KEYDOWN = 0x100;

    const int WM_KEYUP = 0x101;

    //IntPtr windowHandle = Win("notepad");

    //PostMessage(windowHandle, WM_KEYDOWN, (int)Keys.A, 0);

    Thread.Sleep(3000);
    Process[] processes = Process.GetProcessesByName("keytest.txt - Notepad");

    foreach (Process p in processes)
    {

        IntPtr pFoundWindow = p.MainWindowHandle;


    }
    MessageBox.Show("Done");

}

musefan17-Feb-11 5:13

17-Feb-11 5:13

This[^] link any good for you? I am sure that's what you want

Illogical thoughts make me ill

turbosupramk317-Feb-11 5:37

Re: Help with sendkey or postmessage [modified]

17-Feb-11 5:37

Hi,

Thanks for the response.

I believe I am misunderstanding something, my code is below, can you tell me what I am doing wrong?

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;
using System.Net;
using Strings;
using System.IO;
using System.Text.RegularExpressions;
using System.Net.Mail;
using System.Threading;
using System.Diagnostics;
using System.Runtime.InteropServices;



namespace GenericTester
{
    public partial class Form1 : Form
    {
        private static uint SC_RESTORE = 0xF120;
        private static uint SC_MAXIMIZE = 0xF030;
        private static uint SC_MINIMIZE = 0xF020;
        private static uint WM_SYSCOMMAND = 0x0112;
        
        [DllImport("user32.dll")]
        public static extern bool PostMessage(IntPtr hWnd, [MarshalAs(UnmanagedType.U4)] uint Msg, IntPtr wParam, IntPtr lParam);

        [DllImport("User32.Dll", EntryPoint = "PostMessageA")]
        static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);

        [DllImport("user32.dll", EntryPoint = "FindWindowA")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        static extern byte VkKeyScan(string ch); 

     
        public Form1()
        {
            InitializeComponent();
           
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            const int WM_KEYDOWN = 0x100;

            const int WM_KEYUP = 0x101;

           
            Thread.Sleep(3000);
            Process[] processes = Process.GetProcessesByName("javaw");

            foreach (Process p in processes)
            {

                IntPtr pFoundWindow = p.MainWindowHandle;
                PostMessage(pFoundWindow, WM_KEYDOWN, VkKeyScan("{F2}"), 0);
                

            }
            MessageBox.Show("Done");
            
        }

musefan17-Feb-11 6:05

17-Feb-11 6:05

Firstly, do you need that Thread.Sleep?

For the Function Keys I have found it works with the Keycode value. I tried the following with my browser and it refreshed the page. You will need to change the Keycode from F5 to F2.

F2 = 0x71
F5 = 0x74

See here[^] for full list of codes

foreach(Process process in Process.GetProcessesByName(textBoxProcessName.Text))
{
   IntPtr hWnd = process.MainWindowHandle;
   PostMessage(hWnd, WM_KEYDOWN, 0x74, 0);//<-- change to 0x71
}

hope this helps

Illogical thoughts make me ill

modified on Thursday, February 17, 2011 12:41 PM

musefan17-Feb-11 6:07

17-Feb-11 6:07

Also, are you sure "javaw" is the right window you want?

Illogical thoughts make me ill

turbosupramk317-Feb-11 7:25

17-Feb-11 7:25

Hi,

Yes the process in task manager is called javaw ... the code below is the only way I can seem to get it to work? For some reason it requires the Thread.Sleep(2000) or it happens to quickly.

I would rather not use SendKeys, as I would like to send the "F2" keystroke to the window when it is minimized, any ideas?

private void button1_Click(object sender, EventArgs e)
{
    const int WM_KEYDOWN = 0x100;

    const int WM_KEYUP = 0x101;

    Process[] processes = null;
    if (Process.GetProcessesByName("javaw") != null)
    {
       processes = Process.GetProcessesByName("javaw");

    }


    foreach (Process p in processes)
    {
        IntPtr pFoundWindow = p.MainWindowHandle;

        //MessageBox.Show(p.MainWindowHandle + " " + p.MainWindowTitle);
        SetForegroundWindow(pFoundWindow.ToInt32());
        //MessageBox.Show("About to send F2 keystroke");
        Thread.Sleep(2000);
        SendKeys.Send("{F2}");
        //MessageBox.Show("Window int pointer for " + p + " is " + pFoundWindow.ToString());
        PostMessage(pFoundWindow, WM_KEYDOWN, 0x71, 0);//<-- change to 0x71, 0x74 is F5

    }

}

Henry Minute17-Feb-11 6:26

Henry Minute

17-Feb-11 6:26

In addition to the other advice you have been given, you should consider that F5 is pretty much the standard key to use for refresh.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”
I wouldn't let CG touch my Abacus!
When you're wrestling a gorilla, you don't stop when you're tired, you stop when the gorilla is.

turbosupramk317-Feb-11 7:19

17-Feb-11 7:19

Yes it is normally f5, our developers must have overlooked that unfortunately

Constructing a class from a static function

Luc Pattyn17-Feb-11 7:39

Luc Pattyn

17-Feb-11 7:39

First of all I don't understand what a refresh is going to do on a window you are not seeing anyway.

And then I have some doubt a minimized window will be receiving anything.

As your target app seems to be an in-house development, this is what I would suggest:
- create an extra window, make it visible, not shown in taskbar, off-screen, and with a unique title;
- have it override its WndProc and check for a special message (a WM_USER kind of message, not a regular one);

The other app now should:
- locate the target app;
- find the off-screen window based on its title;
- send the Window message your target app will react on.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.

musefan17-Feb-11 1:37

17-Feb-11 1:37

Hi all,

I have been looking at some example code around and wonder if anyone knows what the differences/uses/benefits are of the following two examples for creating an instance of a class (if there are any at all)

Example 1: The Norm (in my experience)

Class Code:

public Person(){
}

Usage Code:

Person person = new Person();

Example 2: Via a Static Method

Class Code:

public static Person CreatePerson(){
   return new Person();
}

Usage Code:

Person person = Person.CreatePerson();

Thanks

Illogical thoughts make me ill

http://henko.net/imperfection/constructors-and-creation-methods/[^]

Xmen Real 17-Feb-11 1:45

Xmen Real

17-Feb-11 1:45

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R0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-iTV.C\y<pjxsg-b$f4ia>

-----------------------------------------------
128 bit encrypted signature, crack if you can

musefan17-Feb-11 2:08

17-Feb-11 2:08

Thanks, I guess I was lacking the term 'Creation Method' is my failed Google attempts.

I think the example use I has seen was perhaps a miss use of this technique, unless of course I missed the point.

My understanding is that the Creation Method would be used if there where multiple (almost template like) default variations of a class. Obviously this could still be achieved by a constructor but I suppose the Create Method way provides distinction as to what you are actually doing.

Perhaps I would be correct in stating the following?..

- If you only have one default set up for a class, use a constructor
- If you have multiple commonly used default set ups then consider a Creation Method style approach

...I guess the later should be used if you were considering using a 'switch' type parameter in a class constructor. i.e. Stick to only property setting parameters in constructors (of course, in .Net 4.0 we don't even need to provide overloads for this Smile | :)

)

Illogical thoughts make me ill

PIEBALDconsult17-Feb-11 4:27

PIEBALDconsult

17-Feb-11 4:27

musefan wrote:
perhaps a miss use of this technique

Yes, probably.

The benefit of well-defined Design Patterns is that they allow developers to discuss situations clearly. The downside is when developers don't understand them, how to implement, and when to implement them.

Not Active17-Feb-11 2:25

Not Active

17-Feb-11 2:25

This is what is called the Factory Pattern http://en.wikipedia.org/wiki/Factory_method_pattern[^]

I know the language. I've read a book. - _Madmatt

musefan17-Feb-11 2:43