如何訪問下拉選定的索引更改？

Question

我是新來的C＃和我創造了這個線程類似於人的用戶控件：

add user control to a form

而已，我用4個下拉列表。我創建了一個名爲CustomBaseUserControl.cs的自定義用戶控件。它具有爲每個下拉菜單選擇的所有索引更改事件。從表單中，將其稱爲TheFormControl，將CustomBaseUserControl放入，如何訪問這些事件更改值？

在此先感謝！

Answer 1

如果需要檢索TheFormControl選定的索引，你既可以

使用變量來存儲上CustomBaseUserControl的價值，在這種情況下，你要聽的的SelectedIndexChanged事件並更新你的價值觀。

觸發自定義選擇的指數從CustomBaseUserControl改爲TheFormControl

-

class CustomBaseUserControl: UserControl{ 
int idx1=-1; 
public CustomBaseUserControl() 
{ 
    Initialize(); 
    //Fill ComboBox 

    //Suscribe Event 
    combobox1.SelectedIndexChanged += combobox1_SelectedIndexChanged; 
} 
    void combobox1_SelectedIndexChanged(object sender, EventArgs e) 
    { 
     int index = combobox1.SelectedIndex; 
     if (index != idx1) 
     { 
     idx1=index; 
     RaiseIndexChanged(e); 
     } 

    } 

     public virtual void RaiseIndexChanged(EventArgs ea) 
    { 
     var handler = OnIndexChanged; 
     if (OnIndexChanged != null) 
      OnIndexChanged(this, ea); 
    } 
    public event EventHandler OnIndexChanged; 
} 

主叫類將是

class TheFormControl: Form 
{ 
    CustomBaseUserControl cb; 
    public TheFormControl() 
    { 
     Initialize(); 
     cb = new CustomBaseUserControl(); 
     cb.OnIndexChanged +=cb_OnIndexChanged; 
    } 
    void cb_OnIndexChanged(object sender, EventArgs e) 
    { 
    // Here you know index has changed on CustomBaseUserControl 
    } 
}