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SpeechRecognizer::RecognizerUpdateReached Event

Occurs when the recognizer pauses to synchronize recognition and other operations.

Namespace:  System.Speech.Recognition
Assembly:  System.Speech (in System.Speech.dll)

public:
 event EventHandler<RecognizerUpdateReachedEventArgs^>^ RecognizerUpdateReached {
	void add (EventHandler<RecognizerUpdateReachedEventArgs^>^ value);
	void remove (EventHandler<RecognizerUpdateReachedEventArgs^>^ value);
}

Applications must use RequestRecognizerUpdate to pause a running instance of SpeechRecognizer before modifying its Grammar objects. For example, while the SpeechRecognizer is paused, you can load, unload, enable, and disable Grammar objects. The SpeechRecognizer raises this event when it is ready to accept modifications.

When you create a delegate for a RecognizerUpdateReached event, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

The following example shows a console application that loads and unloads Grammar objects. The application uses the RequestRecognizerUpdate method to request the speech recognition engine to pause so it can receive an update. The application then loads or unloads a Grammar object.

At each update, a handler for RecognizerUpdateReached event writes the name and status of the currently loaded Grammar objects to the console. As grammars are loaded and unloaded, the application first recognizes the names of farm animals, then the names of farm animals and the names of fruits, then only the names of fruits.

using System;
using System.Speech.Recognition;
using System.Collections.Generic;
using System.Threading;

namespace SampleRecognition
{
  class Program
  {
    private static SpeechRecognizer recognizer;
    public static void Main(string[] args)
    {

      // Initialize a shared speech recognition engine.
      recognizer = new SpeechRecognizer();

      // Create the first grammar - Farm.
      Choices animals = new Choices(new string[] { "cow", "pig", "goat" });
      GrammarBuilder farm = new GrammarBuilder(animals);
      Grammar farmAnimals = new Grammar(farm);
      farmAnimals.Name = "Farm";

      // Create the second grammar - Fruit.
      Choices fruit = new Choices(new string[] { "apples", "peaches", "oranges" });
      GrammarBuilder favorite = new GrammarBuilder(fruit);
      Grammar favoriteFruit = new Grammar(favorite);
      favoriteFruit.Name = "Fruit";

      // Attach event handlers.
      recognizer.SpeechRecognized +=
        new EventHandler<SpeechRecognizedEventArgs>(recognizer_SpeechRecognized);
      recognizer.RecognizerUpdateReached +=
        new EventHandler<RecognizerUpdateReachedEventArgs>(recognizer_RecognizerUpdateReached);
      recognizer.StateChanged += 
        new EventHandler<StateChangedEventArgs>(recognizer_StateChanged);

      // Load the Farm grammar.
      recognizer.LoadGrammar(farmAnimals);
      Console.WriteLine("Grammar Farm is loaded");

      // Pause to recognize farm animals.
      Thread.Sleep(7000);
      Console.WriteLine();

      // Request an update and load the Fruit grammar.
      recognizer.RequestRecognizerUpdate();
      recognizer.LoadGrammarAsync(favoriteFruit);
      Thread.Sleep(5000);

      // Request an update and unload the Farm grammar.
      recognizer.RequestRecognizerUpdate();
      recognizer.UnloadGrammar(farmAnimals);
      Thread.Sleep(5000);

      // Keep the console window open.
      Console.WriteLine();
      Console.WriteLine("Press any key to exit...");
      Console.ReadKey();
    }

    // Put the shared speech recognizer into "listening" mode.
    static void recognizer_StateChanged(object sender, StateChangedEventArgs e)
    {
      if (e.RecognizerState != RecognizerState.Stopped)
      {
        recognizer.EmulateRecognizeAsync("Start listening");
      }
    }

    // At the update, get the names and enabled status of the currently loaded grammars.
    public static void recognizer_RecognizerUpdateReached(
      object sender, RecognizerUpdateReachedEventArgs e)
    {
      Console.WriteLine();
      Console.WriteLine("Update reached:");
      Thread.Sleep(1000);

      string qualifier;
      List<Grammar> grammars = new List<Grammar>(recognizer.Grammars);
      foreach (Grammar g in grammars)
      {
        qualifier = (g.Enabled) ? "enabled" : "disabled";
        Console.WriteLine("  Grammar {0} is loaded and is {1}.",
        g.Name, qualifier);
      }
    }

    // Write the text of the recognized phrase to the console.
    static void recognizer_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
      Console.WriteLine("  Speech recognized: " + e.Result.Text);
    }
  }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4
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