How to generate keyboard text for the active process of Firefox

Question

I can send a text from my C# WinForm app to another application like Notepad using:

SendKeys.SendWait("Hello");

but I need to send text to an html input element in Firefox. There are several ways to select a target application. This SO Question uses code like:

Process p = Process.GetProcessesByName("notepad").FirstOrDefault();
IntPtr h = p.MainWindowHandle;
SetForegroundWindow(h);

to set the desired app to the foreground so it will receive the text. But this does not work with the app named "firefox", probably because it uses not 1 but 4 processes according to the Task Manager.

I tried another approach: right before calling SendKeys.SendWait, just switch back to the last active application just like Alt-Tab does, using code from this SO Question, which works for Notepad, and for the Chrome browser, but not for Firefox.

The purpose of this is to get data from a weight measurement device (scale), connected to the RS232 port, to the html input element in the browser. The same principle of simulating a keyboard is routinely used with USB barcode scanners.

Any idea how to do this with Firefox?

Am I perhaps on the wrong track, and are there perhaps much different methods to get text in the keyboard?

Answer 1

Can't you use WinForms WebBrowser? Also consider using Selenium WebDriver which is available via Nuget. I think it does exactly what you need.

That's an example from docs:

using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;

// Requires reference to WebDriver.Support.dll
using OpenQA.Selenium.Support.UI;

class GoogleSuggest
{
    static void Main(string[] args)
    {
        // Create a new instance of the Firefox driver.
        // Note that it is wrapped in a using clause so that the browser is closed 
        // and the webdriver is disposed (even in the face of exceptions).

        // Also note that the remainder of the code relies on the interface, 
        // not the implementation.

        // Further note that other drivers (InternetExplorerDriver,
        // ChromeDriver, etc.) will require further configuration 
        // before this example will work. See the wiki pages for the
        // individual drivers at http://code.google.com/p/selenium/wiki
        // for further information.
        using (IWebDriver driver = new FirefoxDriver())
        {
            //Notice navigation is slightly different than the Java version
            //This is because 'get' is a keyword in C#
            driver.Navigate().GoToUrl("http://www.google.com/");

            // Find the text input element by its name
            IWebElement query = driver.FindElement(By.Name("q"));

            // Enter something to search for
            query.SendKeys("Cheese");

            // Now submit the form. WebDriver will find the form for us from the element
            query.Submit();

            // Google's search is rendered dynamically with JavaScript.
            // Wait for the page to load, timeout after 10 seconds
            var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(10));
            wait.Until(d => d.Title.StartsWith("cheese", StringComparison.OrdinalIgnoreCase));

            // Should see: "Cheese - Google Search" (for an English locale)
            Console.WriteLine("Page title is: " + driver.Title);
        }
    }
}