We Keep Coding

C# - trigger key down event for active control

I found command System.Windows.Forms.SendKeys.Send() for sending keypress some key. This function work if open external app like a notepad and set focus and I will be see that my Key printed in this text field. How do same but with key down event, System.Windows.Forms.SendKeys.SendDown("A");, for example?
I tried call in Timer this command System.Windows.Forms.SendKeys.Send() but have runtime error associated with very fast taped.

You can't use the SendKeys class for that, unfortunately. You will need to go to a lower level API.
Poking a window with a keydown message
In Windows, keyboard events are sent to windows and controls via the Windows message pump. A piece of code using PostMessage should do the trick:
[DllImport("user32.dll")]
static extern bool PostMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);
const uint WM_KEYDOWN = 0x0100;
void SendKeyDownToProcess(string processName, System.Windows.Forms.Keys key)
{
Process p = Process.GetProcessesByName(processName).FirstOrDefault();
if (p != null)
{
PostMessage(p.MainWindowHandle, WM_KEYDOWN, (int)key, 0);
}
}
Note that the application receiving these events may not do anything with it until a corresponding WM_KEYUP is received. You can get other message constants from here.
Poking a control other than the main window
The above code will send a keydown to the "MainWindowHandle." If you need to send it to something else (e.g. the active control) you will need to call PostMessage with a handle other than p.MainWindowHandle. The question is... how do you get that handle?
This is actually very involved... you will need to temporarily attach your thread to the window's message input and poke it to figure out what the handle is. This can only work if the current thread exists in a Windows Forms application and has an active message loop.
An explanation can be found here, as well as this example:
using System.Runtime.InteropServices;
public partial class FormMain : Form
{
[DllImport("user32.dll")]
static extern IntPtr GetForegroundWindow();
[DllImport("user32.dll")]
static extern IntPtr GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId);
[DllImport("user32.dll")]
static extern IntPtr AttachThreadInput(IntPtr idAttach,
IntPtr idAttachTo, bool fAttach);
[DllImport("user32.dll")]
static extern IntPtr GetFocus();
public FormMain()
{
InitializeComponent();
}
private void timerUpdate_Tick(object sender, EventArgs e)
{
labelHandle.Text = "hWnd: " +
FocusedControlInActiveWindow().ToString();
}
private IntPtr FocusedControlInActiveWindow()
{
IntPtr activeWindowHandle = GetForegroundWindow();
IntPtr activeWindowThread =
GetWindowThreadProcessId(activeWindowHandle, IntPtr.Zero);
IntPtr thisWindowThread = GetWindowThreadProcessId(this.Handle, IntPtr.Zero);
AttachThreadInput(activeWindowThread, thisWindowThread, true);
IntPtr focusedControlHandle = GetFocus();
AttachThreadInput(activeWindowThread, thisWindowThread, false);
return focusedControlHandle;
}
}
The good news-- if SendKeys worked for you, then you might not need to do all this-- SendKeys also sends messages to the main window handle.

open new notepad.exe and write content to it [duplicate]

This question already has answers here:
How to send text to Notepad in C#/Win32?
(3 answers)
Closed 7 years ago.
I would like to launch a new notepad instance and write content to it from my desktop app (WPF). After that it is user's discretion to save the file or not. (I know I can launch new notepad instance using System.Diagnostics.Process.Start("notepad.exe"))
Just like the process if some one manually wants to create a .txt file. He first opens notepad from start menu. Then write something and then save in desired folder.
Is it possible?

try this one source
[DllImport("user32.dll", EntryPoint = "FindWindowEx")]
public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
[DllImport("User32.dll")]
public static extern int SendMessage(IntPtr hWnd, int uMsg, int wParam, string lParam);
private void button1_Click(object sender, EventArgs e)
{
Process [] notepads=Process.GetProcessesByName("notepad");
if(notepads.Length==0)return;
if (notepads[0] != null)
{
IntPtr child= FindWindowEx(notepads[0].MainWindowHandle, new IntPtr(0), "Edit", null);
SendMessage(child, 0x000C, 0, textBox1.Text);
}
}

Is there a way to have my app push its icon to other apps?

I have a WPF app that starts another application, I'd like for my application to change the Icon of this second app. I am able to use GetWindowText and SetWindowText to change the title. Is it possible to do this for the Icon as well?
update
I have no control of the second app.

To change the window title of another application:
Definitions of Win32 API functions and constants:
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern bool SetWindowText(IntPtr hwnd, String lpString);
[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hwnd, int message, int wParam, IntPtr lParam);
private const int WM_SETICON = 0x80;
private const int ICON_SMALL = 0;
private const int ICON_BIG = 1;
Usage:
Process process = Process.Start("notepad");
// If you have just started a process and want to use its main window handle,
// consider using the WaitForInputIdle method to allow the process to finish starting,
// ensuring that the main window handle has been created.
// Otherwise, an exception will be thrown.
process.WaitForInputIdle();
SetWindowText(process.MainWindowHandle, "Hello!");
Icon icon = new Icon(#"C:\Icon\File\Path.ico");
SendMessage(process.MainWindowHandle, WM_SETICON, ICON_BIG, icon.Handle);

In Windows Forms you would use
Icon ico = Icon.ExtractAssociatedIcon(#"C:\WINDOWS\system32\notepad.exe");
this.Icon = ico;
So im guessing for WPF it would be similar.

How do you get a child window using its control ID?

I am new to WINAPI and have figured out how to send a message to another program. The program I am using however I would like to be able to have it click on a specific button. From what I have learned by viewing Spy++ windows handles change for the programs every time they are reloaded and so do the handles for their controls. The control ID stays the same. After two days of trying to figure it out I am here.
under SendMesssageA if I specify the current handle as viewable by Spy++ and use that and run the code it works fine and clicks the button on my external application. I am attempting to use GetDlgItem as I have read that I can get the handle for the control (child window) using it. I am doing something wrong however since no matter what I do it returns 0 or 'null'.
How can I get GetDlgItem to return the child control handle so that I may use it to sendmessage to click that control in the external application?
Thanks for your help an input ahead of time.
[DllImport("User32.dll")]
static extern bool SetForegroundWindow(IntPtr hWnd);
Process[] myProcess = Process.GetProcessesByName("program name here");
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern int SendMessageA(IntPtr hwnd, int wMsg, int wParam, uint lParam);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr GetDlgItem(int hwnd, int childID);
public const int WM_LBUTTONDOWN = 0x0201;
public const int WM_LBUTTONUP = 0x0202;
public void SendClick()
{
IntPtr hwnd = myProcess[0].MainWindowHandle;
SetForegroundWindow(hwnd);
int intCID = 1389;
IntPtr ptrTest = GetDlgItem(hwnd, intCID);
SendKeys.SendWait(" ");
Thread.Sleep(1000);
SendKeys.SendWait("various text to be sent here");
Thread.Sleep(1000);
SendKeys.SendWait("{ENTER}");
Thread.Sleep(1000);
SendMessageA(ptrTest, WM_LBUTTONDOWN, WM_LBUTTONDOWN, 0);
}

I think you have to use the Win32 API to find the "receiving" application window, and then find a child window of that handle.
This is something I found googling Win32 API FindWindow
http://www.c-sharpcorner.com/UploadFile/shrijeetnair/win32api12062005005528AM/win32api.aspx

RadioButton click on another form

We have a legacy program with a GUI that we want to use under control of a C# program to compute some values. We can successfully enter values in the numerical input controls, press the compute button, and read the produced answers from text display boxes.
But we can't seem to control a pair of radio buttons .
Calling CheckRadioButton() returns a code of success, but the control does not change state.
Sending a message of BM_CLICK does not change the state.
Attempts at sending WM_LBUTTONDOWN and WM_LBUTTONUP events haven't changed the state.
Has anyone been successful at "remote control" of radio buttons?
Portions of code to illustrate what we are doing:
[DllImport("user32.dll", EntryPoint="SendMessage")]
public static extern int SendMessageStr(int hWnd, uint Msg, int wParam, string lParam);
[DllImport("user32.dll")]
public static extern int SendMessage(int hWnd, uint Msg, long wParam, long lParam);
[DllImport("user32.dll", EntryPoint="FindWindow", SetLastError=true)]
static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
[DllImport("user32.dll", EntryPoint="CheckRadioButton")]
public static extern bool CheckRadioButton(IntPtr hwnd, int firstID, int lastID, int checkedID);
static IntPtr GetControlById(IntPtr parentHwnd, int controlId) {
IntPtr child = new IntPtr(0);
child = GetWindow(parentHwnd, GetWindow_Cmd.GW_CHILD);
while (GetWindowLong(child.ToInt32(), GWL_ID) != controlId) {
child = GetWindow(child, GetWindow_Cmd.GW_HWNDNEXT);
if (child == IntPtr.Zero) return IntPtr.Zero;
}
return child;
}
// find the handle of the parent window
IntPtr ParenthWnd = new IntPtr(0);
ParenthWnd = FindWindowByCaption(IntPtr.Zero, "Legacy Window Title");
// set "N" to 10
IntPtr hwndN = GetControlById(ParenthWnd, 17);
SendMessageStr(hwndN.ToInt32(), WM_SETTEXT, 0, "10");
// press "compute" button (seems to need to be pressed twice(?))
int hwndButton = GetControlById(ParenthWnd, 6).ToInt32();
SendMessage(hwndButton, BM_CLICK, 0, 0);
SendMessage(hwndButton, BM_CLICK, 0, 0);
// following code runs succesfully, but doesn't toggle the radio buttons
bool result = CheckRadioButton(ParenthWnd, 12, 13, 12);

Send the BM_SETCHECK message. Be sure to use a tool like Spy++ to see the messages.

in this case i used another message BM_SETSTATE
SendMessage((IntPtr)hWnd, Win32Api.BM_SETSTATE, (IntPtr)newState, IntPtr.Zero);