Windows 7 Calculator

The calculator in Windows 7 is probably written in C++, and is a fairly old application. Nevertheless, it fully supports the automation facilities. Windows' accessibility features are also built upon automation, so all standard Windows applications have to support it.

So, let's implement the necessary plumbing to control the calculator. We do that by inheriting the Automated class and implementing the ICalculator interface.

namespace Examples.UITests
{
	using System;
	using System.Windows.Automation;

	class Win7Calculator : Automated, ICalculator
	{

The only data we store is the automation element for the calculator's display text box.

		private AutomationElement _result;

Opening and Closing the Calculator

The calculator is launched when the class is created, so we start it in the constructor. After the calculator started successfully, we find the automation element for the text box representing the result display. We find the text box by it's automation ID property, since it does not have a name.

		public Win7Calculator ()
		{
			StartApp ("Calc.exe", "Calculator");
			_result = _root.FindFirst (TreeScope.Descendants, 
				new PropertyCondition (AutomationElement.AutomationIdProperty, "150"));
			if (_result == null)
				throw new Exception ("Could not find result box");
			Clear ();
		}

Disposing the object calls the inherited QuitApp method, which closes the calculator.

		public void Dispose ()
		{
			QuitApp ();
		}

Pushing Digit Buttons

The digit buttons in Windows 7 calculator are named simply with numbers from 0 to 9. So we can locate the buttons easily and use the inherited helper methods to push them.

		public void Digit (byte number)
		{
			if ((number < 0) || (number > 9))
				throw new ArgumentException ("mumber must be between 0-9");
			GetInvokePattern (GetButton (number.ToString ())).Invoke ();
		}

Reading the Result

To get the result displayed currently, we just read the name property of the automation element we stored previously. The following helper method returns the result as string.

		public string GetResult ()
		{
			return _result.GetCurrentPropertyValue (
				AutomationElement.NameProperty).ToString ();
		}

We need to convert the result to a double to implement the ICalculator interface's Display property. We try to parse the result and if we fail, we return NaN.

		public double Display => 
			double.TryParse (GetResult (), out double result) ? 
				result : 
				double.NaN;

To check if a result is available, we again just try to parse it.

		public bool ResultAvailable =>
			double.TryParse (GetResult (), out double result);

Pushing Operator Buttons

The operator buttons are also named quite logically in the automation element tree, so pushing them is just a matter of calling the inherited PushButton method with the correct name.

		public void Add ()
		{
			PushButton ("Add");
		}

		public void Clear ()
		{
			PushButton ("Clear");
		}

		public void Divide ()
		{
			PushButton ("Divide");
		}

		public void Multiply ()
		{
			PushButton ("Multiply");
		}

		public void Subtract ()
		{
			PushButton ("Subtract");
		}

		public void Equals ()
		{
			PushButton ("Equals");
		}
	}
}

Next Steps

That was pretty easy. Now we can do the same drill for Windows 10 calculator.