SemanticValue.Item Property

Article
10/07/2009

Provides read-only indexing child SemanticValue instances belonging to the current SemanticValue.

Namespace: Microsoft.Speech.Recognition
Assembly: Microsoft.Speech (in microsoft.speech.dll)

Syntax

'Declaration

Parameters

key
A System.String containing a key for a KeyValuePair<String, SemanticValue> contained in the current instance of SemanticValue.

Property Value

Returns an instance of SemanticValue that is a child of the current SemanticValue and indexable as part of a key value pair: KeyValuePair<String, SemanticValue>.

Exceptions

Exception type	Condition
KeyNotFoundException	Thrown if no child member of the current instance of SemanticValue has the key matching the key parameter.
InvalidOperationException	Thrown is code attempts to change the SemanticValue at a given index.

Remarks

The Item is read-only and generates exceptions if members are modified.

Evaluating accessing by key value, for instance semantic["myKey"].Value, can only be done at run time, not at code computation. Specifying a key not present will generate an exception.

The presence of a given key can be found using the ContainsKey property on an SemanticValue instance.

Example

The example below shows a handler for a SpeechRecognized event designed to handle commands to change foreground and background color.

After dealing with the case of a phrase that is recognized, but has no semantic structure, the handler checks for the presence of appropriate keys applyChgToBackground, colorRGBValueList, or colorStringList and used the Item property to obtain the nodes with needed information.

The use of Item is highlighted below.

newGrammar.SpeechRecognized +=
    delegate(object sender, SpeechRecognizedEventArgs eventArgs) {
        // Retrieve the value of the semantic property.
        bool changeBackGround = true;
        string errorString = "";
        SemanticValue semantics = eventArgs.Result.Semantics;

        Color newColor = Color.Empty;
        
        try {
            if (semantics.Count == 0 && semantics.Value==null){
                
                //This signature of recognition by grammar with no semantic
                ////We have to parse the string. hope last word is color, search for background or forground in input
                if (eventArgs.Result.Text.Contains("foreground")) {
                    changeBackGround = false;
                }
                string cName = eventArgs.Result.Words[eventArgs.Result.Words.Count - 1].Text;
                newColor = Color.FromName(cName);
            
            }else if (semantics.ContainsKey("colorStringList") ^ semantics.ContainsKey("colorRGBValueList")) {
                //Check background vs foreground

                if (semantics.ContainsKey("applyChgToBackground")) {
                    changeBackGround = semantics["applyChgToBackground"].Value is bool;
                }

                //Get color value
                if (semantics.ContainsKey("colorStringList")) {
                    newColor = Color.FromName((string)semantics["colorStringList"].Value);
                }
                if (semantics.ContainsKey("colorRGBValueList")) {
                    newColor = System.Drawing.Color.FromArgb((int)semantics["colorRGBValueList"].Value);
                }
            } else {
                //we have a semantics that does not contain the keys we support, throw an exception.
                throw(new Exception("Unsupported semantics keys found."));
            }

        } catch (Exception exp) {
            MessageBox.Show(String.Format("Unable to process color semantics.:\n{0}\n", exp.Message));
            return;
        }
        //Change colors, either foreground or background.
        if (changeBackGround) {
            BackColor = newColor;
            float Bright = BackColor.GetBrightness();
            float Hue = BackColor.GetHue();
            float Sat = BackColor.GetSaturation();
            //Make sure the text is readable regardless of background.
            if (BackColor.GetBrightness() <= .50) {
                ForeColor = Color.White;
            } else {
                ForeColor = Color.Black;
            }
        } else {
            ForeColor = newColor;
            float Bright = ForeColor.GetBrightness();
            float Hue = ForeColor.GetHue();
            float Sat = ForeColor.GetSaturation();
            //Make sure the text is readable regardless of Foreground.
            if (ForeColor.GetBrightness() <= .50) {
                BackColor = Color.White;
            } else {
                BackColor = Color.Black;
            }
        }
        Return;

};

Thread Safety

All public static (Shared in Visual Basic) members of this type are thread-safe. Instance members are not guaranteed to be thread-safe.

Platforms

Development Platforms

Windows XP Professional with Service Pack 2 (SP2), Windows Server 2003, Windows Vista Ultimate Edition, Windows Vista Business Edition, Windows Vista Enterprise Edition