SemanticValue.Item[String] 属性

定义

命名空间:

System.Speech.Recognition

程序集:

System.Speech.dll

包:

System.Speech v10.0.0-preview.2.25163.2

Source:

SemanticValue.cs

返回属于当前 SemanticValue的子SemanticValue实例。

public:
 property System::Speech::Recognition::SemanticValue ^ default[System::String ^] { System::Speech::Recognition::SemanticValue ^ get(System::String ^ key); void set(System::String ^ key, System::Speech::Recognition::SemanticValue ^ value); };

public System.Speech.Recognition.SemanticValue this[string key] { get; set; }

member this.Item(string) : System.Speech.Recognition.SemanticValue with get, set

Default Public Property Item(key As String) As SemanticValue

参数

key

String

在 SemanticValue 的当前实例中包含 KeyValuePair<String, SemanticValue> 的密钥。

属性值

SemanticValue

返回当前 的子级， SemanticValue 该子项可作为键值对的一部分进行索引： KeyValuePair<String,SemanticValue>。

实现

Item[TKey]

例外

KeyNotFoundException

当前实例 SemanticValue 的子成员没有与 参数匹配的 key 键。

InvalidOperationException

代码尝试更改 SemanticValue 指定索引处的 。

示例

以下示例演示事件的处理程序， SpeechRecognized 该处理程序旨在处理更改前景色和背景色的命令。

处理没有语义结构的已识别短语后，处理程序使用 ContainsKey (applyChgToBackground、 colorRGBValueList或 colorStringList)检查是否存在适当的键，然后使用 Item[] 属性获取具有所需信息的节点。

下面突出显示了 的 Item[] 用法。

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)
      {
        // Signifies recognition by a grammar with no semantics.
        // Parse the string, assuming that the last word is color,
        //  searching for background or foreground 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"))
      {

        // Determine whether to change background or foreground.
        if (semantics.ContainsKey("applyChgToBackground"))
        {
          changeBackGround = semantics["applyChgToBackground"].Value is bool;
        }

        // Get the RGB 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
      {

        // Throw an exception if the semantics do not contain the keys we
        // support.
        throw(new Exception("Unsupported semantic 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 that 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 that text is readable regardless of the foreground.
      if (ForeColor.GetBrightness() <= .50)
      {
        BackColor = Color.White;
      }
      else
      {
        BackColor = Color.Black;
      }
    }
    return;
  };

注解

Item[]是只读的，如果修改成员，则会生成异常。

只能在运行时（而不是编译时）按键值访问数据，例如检查 semantic["myKey"].Value。 指定不存在的键将生成异常。

若要检测是否存在给定键，请在 实例上使用 ContainsKeySemanticValue 属性。