Windows核心编程笔记第三篇（代码精读VOID Dlg_PopulateProcessList(HWND hwnd) ）

相关MSDN资料整理

WM_COMMAND Notification

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The WM_COMMAND message is sent when the user selects a command item from a menu, when a control sends a notification message to its parent window, or when an accelerator keystroke is translated.

Syntax

WM_COMMAND    WPARAM wParam    LPARAM lParam;

Parameters

wParam

The high-order word specifies the notification code if the message is from a control. If the message is from an accelerator, this value is 1. If the message is from a menu, this value is zero.

The low-order word specifies the identifier of the menu item, control, or accelerator.

lParam

Handle to the control sending the message if the message is from a control. Otherwise, this parameter is NULL.

Return Value

If an application processes this message, it should return zero.

 

Remarks

Accelerator keystrokes that select items from the window menu are translated into WM_SYSCOMMAND messages.

If an accelerator keystroke occurs that corresponds to a menu item when the window that owns the menu is minimized, no WM_COMMAND message is sent. However, if an accelerator keystroke occurs that does not match any of the items in the window's menu or in the window menu, a WM_COMMAND message is sent, even if the window is minimized.

If an application enables a menu separator, the system sends a WM_COMMAND message with the low-word of the wParam parameter set to zero when the user selects the separator.

Windows 98/Me, Windows 2000/XP: If a menu is defined with a MENUINFO.dwStyle value of MNS_NOTIFYBYPOS, WM_MENUCOMMAND is sent instead of WM_COMMAND.

CBN_SELCHANGE Notification

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The CBN_SELCHANGE notification message is sent when the user changes the current selection in the list box of a combo box. The user can change the selection by clicking in the list box or by using the arrow keys. The parent window of the combo box receives this notification in the form of a WM_COMMAND message with CBN_SELCHANGE in the high-order word of the wParam parameter.

Syntax

CBN_SELCHANGE    WPARAM wParam    LPARAM lParam;

Parameters

wParam

The low-order word specifies the control identifier of the combo box.

The high-order word specifies the notification message.

lParam

Handle to the combo box.

Return Value

No return value.

Remarks

To get the index of the current selection, send the CB_GETCURSEL message to the control.

The CBN_SELCHANGE notification message is not sent when the current selection is set using the CB_SETCURSEL message.

MAKEWPARAM Macro

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The MAKEWPARAM macro creates a value for use as a wParam parameter in a message. The macro concatenates the specified values.

Syntax

WPARAM MAKEWPARAM(

    WORD wLow,    WORD wHigh);

Parameters

wLow

Specifies the low-order word of the new value.

wHigh

Specifies the high-order word of the new value.

Return Value

The return value is a WPARAM value.

//更新列表显示内容
VOID Dlg_PopulateProcessList(HWND hwnd) {

   HWND hwndList = GetDlgItem(hwnd, IDC_PROCESSMODULELIST);
   //通过资源ID获取列表框句柄
   //SetWindowRedraw(hwndList, FALSE);
   SendMessage(hwndList, WM_SETREDRAW, (WPARAM)(FALSE), 0L);
   //禁止重绘
   //ComboBox_ResetContent(hwndList);
   SendMessage(hwndList,CB_RESETCONTENT,0,0);
   //CB_RESETCONTENT此消息清空列表所有项
   CToolhelp thProcesses(TH32CS_SNAPPROCESS);
   //Includes all processes in the system in the snapshot.
   //包含了全部系统进程信息
   ///*CreateToolhelp32Snapshot*/( TH32CS_SNAPPROCESS, 0 );
   PROCESSENTRY32 pe = { sizeof(pe) };
   //PROCESSENTRY32进程入口点信息
   BOOL fOk = thProcesses.ProcessFirst(&pe);
   //将第一个进程的入口点信息存入pe
   for (; fOk; fOk = thProcesses.ProcessNext(&pe))
   //遍历所有进程
   {
      TCHAR sz[1024];

      // Place the process name (without its path) & ID in the list
          //返回文件名所在位置的指针
      PCTSTR pszExeFile = _tcsrchr(pe.szExeFile, TEXT('\\'));
      if (pszExeFile == NULL) pszExeFile = pe.szExeFile;//只有文件名没路径的情况下上一句返回空指针
      else pszExeFile++; // Skip over the slash如果是全路径的话需要去掉文件名前的斜线
      wsprintf(sz, TEXT("%s     (0x%08X)"), pszExeFile, pe.th32ProcessID);//格式化到字符串
      //int n = ComboBox_AddString(hwndList, sz);//为列表框添加一个选项文字返回值是从0开始的索引
          int n =SendMessage((hwndList), CB_ADDSTRING, 0L, (LPARAM)(LPCTSTR)(sz));

      // Associate the process ID with the added item
      //ComboBox_SetItemData(hwndList, n, pe.th32ProcessID);//设置列表框该条记录的值为th32ProcessID方便程序访问value
          SendMessage((hwndList), CB_SETITEMDATA, (WPARAM)(int)(n), (LPARAM)(pe.th32ProcessID));
   }
   SendMessage((hwndList), CB_SETCURSEL, (WPARAM)(int)(0), 0L);
   //ComboBox_SetCurSel(hwndList, 0);  // Select the first entry设置默认显示的值
   //WPARM为从0开始的索引值如果为-1则清空列表

   // Simulate the user selecting this first item so that the
   // results pane shows something interesting
   //FORWARD_WM_COMMAND(hwnd, IDC_PROCESSMODULELIST,
   //   hwndList, CBN_SELCHANGE, SendMessage);
   SendMessage((hwnd), WM_COMMAND, MAKEWPARAM((UINT)(IDC_PROCESSMODULELIST),(UINT)(CBN_SELCHANGE)), (LPARAM)(HWND)(hwndList));
   //这次真的发现问题..不过还是要感谢看雪论坛上那篇一年前的帖子
   //当用户在 list box of a combo box 中改变选择项时Windows将会发送WPARM中高位为CBN_SELCHANGE的WM_COMMAND消息
   SetWindowRedraw(hwndList, TRUE);//设置列表为可重绘状态
   InvalidateRect(hwndList, NULL, FALSE);//使客户区域无效为了发送WM_Parint小心重绘列表框
}