CListbox

CListBox:

当我第一次看MSDN里关于CListBox的介绍时，我想MFC真的很强大，因为封装了很多的方法实现CListBox的操作，操作起来如此简单，所以很有必要看看CListBox。

初识CListbox:

先来看看MSDN:

The CListBox class provides the functionality of a Windows list box. A list box displays a list of items, such as filenames, that the user can view and select.

In a single-selection list box, the user can select only one item. In a multiple-selection list box, a range of items can be selected. When the user selects an item, it is highlighted and the list box sends a notification message to the parent window.

You can create a list box either from a dialog template or directly in your code. To create it directly, construct theCListBox object, then call the Create member function to create the Windows list-box control and attach it to theCListBox object. To use a list box in a dialog template, declare a list-box variable in your dialog box class, then useDDX_Control in your dialog box class's DoDataExchange function to connect the member variable to the control. (ClassWizard does this for you automatically when you add a control variable to your dialog box class.)

MSDN清晰的介绍了listbox的功用和MFC中创建listbox的方法，

Listbox里可以存放列表项，例如文件名，用户可以用来查看和选择。

在一个单选的列表框中，用户只能选择其中一个项，在多选的列表框中，用户可以选择一个范围内的所有项，当用户选择一个项时，这一项会高亮显示并且会发送一个通知消息给它的父窗口，当然这要求我们自己进行处理。

 

当我们利用代码创建listbox时，首先应该生成一个CListbox对象，然后调用Create方法创建它。当我们在对话框模板上生成listbox时，先要在对话框类中声明一个CListbox的变量，然后点击鼠标拖放控件即可，此时MFC向导会做如下工作：使用DDX_Control在DoDataExChnage函数里将刚才我们声明的CListbox变量与拖放的listbox控件进行绑定。

现在我们分别以两种方案实现CListbox简单应用（包括创建和单击事件）

方案一：代码实现

在view类里声明一个CListbox对象：

private:

           CListBox m_listbox;

然后再view类的OnCreate消息里处理创建，当然这个消息我们要自己添加（通过MFC向导添加WM_CREATE消息）

int CListBoxView::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

      if (CView::OnCreate(lpCreateStruct) == -1)

           return -1;

 

       

      // TODO: 在此添加您专用的创建代码

 

m_listbox.Create(WS_CHILD|WS_VISIBLE|LBS_STANDARD|WS_HSCROLL|WS_BORDER  ,

           CRect(10,10,200,200), this, 1);

 

       

 

      // Add 256 items to the list box.

      CString str;

      for (int i=0;i < 256;i++)

      {

           str.Format(_T("item string %d"), i);

           m_listbox.AddString( str );

      }

      m_listbox.SetTopIndex(m_listbox.GetCount()-1);//初始化首项

return 0;

}

一切搞定，现在我们可以处理事件了：

先来看看MSDN:

If you want to handle Windows notification messages sent by a list box to its parent (usually a class derived fromCDialog), add a message-map entry and message-handler member function to the parent class for each message.

Each message-map entry takes the following form:

ON_Notification( id,memberFxn )

where id specifies the child window ID of the list-box control sending the notification andmemberFxn is the name of the parent member function you have written to handle the notification.

The parent’s function prototype is as follows:

afx_msg void memberFxn( );

Following is a list of potential message-map entries and a description of the cases in which they would be sent to the parent:

• ON_LBN_DBLCLK The user double-clicks a string in a list box. Only a list box that has theLBS_NOTIFY style will send this notification message.
• ON_LBN_ERRSPACE The list box cannot allocate enough memory to meet the request.
• ON_LBN_KILLFOCUS The list box is losing the input focus.
• ON_LBN_SELCANCEL The current list-box selection is canceled. This message is only sent when a list box has theLBS_NOTIFY style.
• ON_LBN_SELCHANGE The selection in the list box is about to change. This notification is not sent if the selection is changed by theCListBox::SetCurSel member function. This notification applies only to a list box that has theLBS_NOTIFY style. The LBN_SELCHANGE notification message is sent for a multiple-selection list box whenever the user presses an arrow key, even if the selection does not change.
• ON_LBN_SETFOCUS The list box is receiving the input focus.
• ON_WM_CHARTOITEM An owner-draw list box that has no strings receives aWM_CHAR message.
• ON_WM_VKEYTOITEM A list box with the LBS_WANTKEYBOARDINPUT style receives aWM_KEYDOWN message.

很多是不是，不过这里我们只会用到ON_LBN_DBLCLK消息，

显然，控件的事件响应都同出一辙，有没要看到上面说的按钮也和这一样

响应事件：

1.    添加函数

Public:

`afx_msg void OnListBoxDbClick();

2.    添加消息映射

BEGIN_MESSAGE_MAP(CListBoxView, CView)

ON_LBN_DBLCLK(1,&CListBoxView::OnListBoxDbClick)//这里的1是控件ID

END_MESSAGE_MAP()

 

3.    处理消息

afx_msg void CListBoxView::OnListBoxDbClick()

{

int nIndex = m_listbox.GetCurSel();

int nCount = m_listbox.GetCount();

CString str;

m_listbox.GetText(nIndex,str);

if ((nIndex != LB_ERR) && (nCount > 1))

{

      MessageBox(str);

}

 

}

关于方案二，这里就不介绍了，因为就是简单的拖拉控件即可，消息响应和上面是一样