SemanticValue.Item[String] 属性

定义

命名空间:

System.Speech.Recognition

程序集:

System.Speech.dll

包:

System.Speech v9.0.0-preview.3.24172.9

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。