I tried to keep this procedure as generic as possible, so that it will work whether the application you're watching is already running when your app is started or not.
You just need to provide the watched Application's Process Name or its Main Window Title to let the procedure identify this application.
Use one of these Fields and the corresponding Enumerator:
private string appProcessName = "theAppProcessName"; and
FindWindowMethod.ProcessName
// Or
private string appWindowTitle = "theAppMainWindowTitle"; and
FindWindowMethod.Caption
passing these values to the procedure that starts the watcher, e.g., :
StartAppWatcher(appProcessName, FindWindowMethod.ProcessName);
As you can see - since you tagged your question as winforms - this is a complete Form (named frmWindowWatcher) that contains all the logic required to perform this task.
How does it work:
- When you start
frmWindowWatcher, the procedure verifies whether the watched application (here, identified using its Process name, but you can change the method, as already described), is already running.
If it is, it initializes a support class, ElementWindow, which will contain some informations about the watched application.
I added this support class in case you need to perform some actions if the watched application is already running (in this case, the ElementWindow windowElement Field won't be null when the StartAppWatcher() method is called). These informations may also be useful in other cases.
- When a new Windows is opened in the System, the procedure verifies whether this Window belongs to the watched application. If it does, the Process ID will be the same. If the Windows is a MessageBox (identified using its standard
ClassName: #32770) and it belongs to the watched Application, an AutomationEventHandler is attached to the child OK Button.
Here, I'm using a Delegate: AutomationEventHandler DialogButtonHandler for the handler and an instance Field (AutomationElement msgBoxButton) for the Button Element, because these references are needed to remove the Button Click Handler when the MessageBox is closed.
- When the MessageBox's
OK Button is clicked, the MessageBoxButtonHandler method is called. Here, you can determine which action to take at this point.
- When the
frmWindowWatcher Form is closed, all Automation Handlers are removed, calling the Automation.RemoveAllEventHandlers() method, to provide a final clean up and prevent your app from leaking resources.
using System.Diagnostics;
using System.Linq;
using System.Windows.Automation;
using System.Windows.Forms;
public partial class frmWindowWatcher : Form
{
AutomationEventHandler DialogButtonHandler = null;
AutomationElement msgBoxButton = null;
ElementWindow windowElement = null;
int currentProcessId = 0;
private string appProcessName = "theAppProcessName";
//private string appWindowTitle = "theAppMainWindowTitle";
public enum FindWindowMethod
{
ProcessName,
Caption
}
public frmWindowWatcher()
{
InitializeComponent();
using (var proc = Process.GetCurrentProcess()) {
currentProcessId = proc.Id;
}
// Identify the application by its Process name...
StartAppWatcher(appProcessName, FindWindowMethod.ProcessName);
// ... or by its main Window Title
//StartAppWatcher(appWindowTitle, FindWindowMethod.Caption);
}
protected override void OnFormClosed(FormClosedEventArgs e)
{
Automation.RemoveAllEventHandlers();
base.OnFormClosed(e);
}
private void StartAppWatcher(string elementName, FindWindowMethod method)
{
windowElement = GetAppElement(elementName, method);
// (...)
// You may want to perform some actions if the watched application is already running when you start your app
Automation.AddAutomationEventHandler(WindowPattern.WindowOpenedEvent, AutomationElement.RootElement,
TreeScope.Subtree, (elm, e) => {
AutomationElement element = elm as AutomationElement;
try
{
if (element == null || element.Current.ProcessId == currentProcessId) return;
if (windowElement == null) windowElement = GetAppElement(elementName, method);
if (windowElement == null || windowElement.ProcessId != element.Current.ProcessId) return;
// If the Window is a MessageBox generated by the watched app, attach the handler
if (element.Current.ClassName == "#32770")
{
msgBoxButton = element.FindFirst(TreeScope.Descendants,
new PropertyCondition(AutomationElement.NameProperty, "OK"));
if (msgBoxButton != null && msgBoxButton.GetSupportedPatterns().Any(p => p.Equals(InvokePattern.Pattern)))
{
Automation.AddAutomationEventHandler(
InvokePattern.InvokedEvent, msgBoxButton, TreeScope.Element,
DialogButtonHandler = new AutomationEventHandler(MessageBoxButtonHandler));
}
}
}
catch (ElementNotAvailableException) {
// Ignore: this exception may be raised if you show a modal dialog,
// in your own app, that blocks the execution. When the dialog is closed,
// AutomationElement element is no longer available
}
});
Automation.AddAutomationEventHandler(WindowPattern.WindowClosedEvent, AutomationElement.RootElement,
TreeScope.Subtree, (elm, e) => {
AutomationElement element = elm as AutomationElement;
if (element == null || element.Current.ProcessId == currentProcessId || windowElement == null) return;
if (windowElement.ProcessId == element.Current.ProcessId) {
if (windowElement.MainWindowTitle == element.Current.Name) {
windowElement = null;
}
}
});
}
private void MessageBoxButtonHandler(object sender, AutomationEventArgs e)
{
Console.WriteLine("Dialog Button clicked at : " + DateTime.Now.ToString());
// (...)
// Remove the handler after, since the next MessageBox needs a new handler.
Automation.RemoveAutomationEventHandler(e.EventId, msgBoxButton, DialogButtonHandler);
}
private ElementWindow GetAppElement(string elementName, FindWindowMethod method)
{
Process proc = null;
try {
switch (method) {
case FindWindowMethod.ProcessName:
proc = Process.GetProcessesByName(elementName).FirstOrDefault();
break;
case FindWindowMethod.Caption:
proc = Process.GetProcesses().FirstOrDefault(p => p.MainWindowTitle == elementName);
break;
}
return CreateElementWindow(proc);
}
finally {
proc?.Dispose();
}
}
private ElementWindow CreateElementWindow(Process process) =>
process == null ? null : new ElementWindow(process.ProcessName) {
MainWindowTitle = process.MainWindowTitle,
MainWindowHandle = process.MainWindowHandle,
ProcessId = process.Id
};
}
Support class, used to store informations on the watched application:
It's initialized using the App's Process Name:
public ElementWindow(string processName)
but of course you can change it as required, using the Window Title as described before, or even remove the initialization's argument if you prefer (the class just need to not be null when the watched Application has been detected and identified).
using System.Collections.Generic;
public class ElementWindow
{
public ElementWindow(string processName) => this.ProcessName = processName;
public string ProcessName { get; set; }
public string MainWindowTitle { get; set; }
public int ProcessId { get; set; }
public IntPtr MainWindowHandle { get; set; }
}
