学习MiniGUI之控件篇

   对每个控件而言，MiniGUI都为其定义了几个重要的数据结构：
1. WNDCLASS：窗口类信息，主要定义了控件的外观，风格等参数，用来注册控件时使用
typedef struct _WNDCLASS
{
    /** 类名，比如ListExCtrl */
    char*   spClassName;
    /** internal field, operation type */
    DWORD   opMask;
    /** 窗口的风格 */
    DWORD   dwStyle;
    /** 扩展风格 */
    DWORD   dwExStyle;
    /** 光标句柄 */
    HCURSOR hCursor;
    /** 背景色的像素值 */
    int     iBkColor;
    /** 窗口消息回调处理函数 */
    int     (*WinProc) (HWND, int, WPARAM, LPARAM);
    /** 私有数据区 */
    DWORD dwAddData;
} WNDCLASS;
typedef WNDCLASS* PWNDCLASS;

2. CTRLCLASSINFO：以上类信息的控制结构，内部使用
typedef struct _CTRLCLASSINFO
{
    char      name[MAXLEN_CLASSNAME + 1];
    DWORD     dwStyle;          // Default control styles.
    DWORD     dwExStyle;        // Default control extended styles.
    HCURSOR   hCursor;          // control cursor
    int       iBkColor;         // control background color.
    int (*ControlProc)(HWND, int, WPARAM, LPARAM);
                                // control procedure.
    DWORD dwAddData;            // the additional data.
    int nUseCount;              // use count.
    struct _CTRLCLASSINFO*  next;
                                // next class info
}CTRLCLASSINFO;
typedef CTRLCLASSINFO* PCTRLCLASSINFO;

3. CONTROL：定义了一个具体控件的形状，外观，风格，背景色等参数
typedef struct tagCONTROL
{
    short DataType;         // the data type
    short WinType;          // the window type
    int left, top;          // the position of control in main window's
    int right, bottom;      // client area.
    int cl, ct;             // the positio of control client in main window's
    int cr, cb;             // client area.
    DWORD dwStyle;          // the styles of child window.
    DWORD dwExStyle;        // the extended styles of child window.
    int iBkColor;     // the background color.
    HMENU hMenu;     // handle of menu.
    HACCEL hAccel;          // handle of accelerator table.
    HCURSOR hCursor;     // handle of cursor.
    HICON hIcon;      // handle of icon.
    HMENU hSysMenu;         // handle of system menu.
    PLOGFONT pLogFont;      // pointer to logical font.
    HDC   privCDC;          // the private client DC.
    INVRGN InvRgn;          // the invalid region of this control.
    PGCRINFO pGCRInfo;      // pointer to global clip region info struct.
    PZORDERNODE pZOrderNode;
                            // the Z order node,
                            // only for control with WS_EX_CTRLASMAINWIN.
    PCARETINFO pCaretInfo;  // pointer to system caret info struct.
    DWORD dwAddData;        // the additional data.
    DWORD dwAddData2;       // the second addtional data.
    int (*ControlProc) (HWND, int, WPARAM, LPARAM);
    char* spCaption;         // the caption of control.
    int   id;                // the identifier of child window.
    SCROLLBARINFO vscroll;   // the vertical scroll bar information.
    SCROLLBARINFO hscroll;   // the horizital scroll bar information.
    PMAINWIN pMainWin;       // the main window that contains this control.
    struct tagCONTROL* pParent;// the parent of this control.
    /*
     * Child windows.
     */
    struct tagCONTROL* children;
                             // the first child control.
    struct tagCONTROL* active;
                             // the active child control.
    struct tagCONTROL* old_under_pointer;
                             // the old under pointer child control.
    struct tagCONTROL* primitive;
                             // the primitive child of mouse event.
    NOTIFPROC notif_proc;    // the notification callback procedure.
    /*
     * window element data.
     */
    struct _wnd_element_data* wed;
    /*
     * The following members are only implemented for control.
     */
    struct tagCONTROL* next;   // the next sibling control.
    struct tagCONTROL* prev;   // the prev sibling control.
    PCTRLCLASSINFO pcci;     // pointer to Control Class Info struct.
}CONTROL;
typedef CONTROL* PCONTROL;

控件注册：
控件在可以被使用之前需要调用RegisterWindowClass函数，在这个函数里 向HWND_DESKTOP窗口管理器发送MSG_REGISTERWNDCLASS消息。这里可以看到传入的参数是一个pWndClass的指针
 return SendMessage (HWND_DESKTOP,
  MSG_REGISTERWNDCLASS, 0, (LPARAM)pWndClass) == ERR_OK;

HWND_DESKTOP窗口管理器在它的消息处理函数DesktopWinProc函数中如何处理MSG_REGISTERWNDCLASS消息？
        case MSG_REGISTERWNDCLASS:
            return AddNewControlClass ((PWNDCLASS)lParam);
调用了AddNewControlClass函数，该函数将控件类信息添加到MiniGUI维护的一张保存所有控件的CTRLCLASSINFO的表中去，该表名为ccitable，按字母分成26个链表，AddNewControlClass函数为待添加控件生成一个CTRLCLASSINFO实例，根据传入的PWNDCLASS结构的实例，填充相应的数据，并加入到相应的ccitable链表中。

创建控件：
注册完控件就可以使用CreateWindow创建一个控件。CreateWindow是CreateWindowEx的一个宏。
#define CreateWindow(class_name, caption, style,        \
                id, x, y, w, h, parent, add_data)       \
        CreateWindowEx(class_name, caption, style, 0,   \
                        id, x, y, w, h, parent, add_data)
CreateWindow首先向HWND_DESKTOP窗口管理器发送一个MSG_GETCTRLCLASSINFO消息，获取CTRLCLASSINFO信息，然后定义一个PCONTROL变量，对控件进行初始化，然后向HWND_DESKTOP窗口管理器发送一个MSG_NEWCTRLINSTANCE消息
 SendMessage (HWND_DESKTOP,
  MSG_NEWCTRLINSTANCE, (WPARAM)hParentWnd, (LPARAM)pNewCtrl);
接着向新创建的控件本身发送MSG_CREATE消息：
 if (SendMessage ((HWND)pNewCtrl, MSG_CREATE, (WPARAM)hParentWnd, (LPARAM)dwAddData)) {
  SendMessage (HWND_DESKTOP,
   MSG_REMOVECTRLINSTANCE, (WPARAM)hParentWnd, (LPARAM)pNewCtrl);
  goto error;
 }