wxWidgets源码分析-事件机制（上）

wxEvent(int winid = 0, wxEventType commandType = wxEVT_NULL )

// this function is used to create a copy of the event polymorphically and
// all derived classes must implement it because otherwise wxPostEvent()
// for them wouldn't work (it needs to do a copy of the event)
virtual wxEvent *Clone() const = 0;

protected:
    // the propagation level: while it is positive, we propagate the event to
    // the parent window (if any)
    //
    // this one doesn't have to be public, we don't have to worry about
    // backwards compatibility as it is new
    int               m_propagationLevel;

// the predefined constants for the number of times we propagate event
// upwards window child-parent chain
enum Propagation_state
{
    // don't propagate it at all
    wxEVENT_PROPAGATE_NONE = 0,

    // propagate it until it is processed
    wxEVENT_PROPAGATE_MAX = INT_MAX
};

wxEvent::wxEvent(int theId, wxEventType commandType )
{
    // ......
    m_propagationLevel = wxEVENT_PROPAGATE_NONE;
}

wxCommandEvent::wxCommandEvent(wxEventType commandType, int theId)
              : wxEvent(theId, commandType)
{
     // ......
    // the command events are propagated upwards by default
    m_propagationLevel = wxEVENT_PROPAGATE_MAX;
}

//common/event.cpp
bool wxEvtHandler::ProcessEvent(wxEvent& event)
{
     // ....
        // 事件哈希表查找处理（这里会搜索父类）
        if ( GetEventHashTable().HandleEvent(event, this) )
            return true;


     // ....
    // EvtHandler类组成一个栈，搜索下一个
    if ( GetNextHandler() )
    {
        if ( GetNextHandler()->ProcessEvent(event) )
            return true;
    }

    // .....
    // 继续上传递，这是个虚函数，对于wxWindow向父窗口传递 
    return TryParent(event);
}

struct WXDLLIMPEXP_BASE wxEventTableEntry
{
    // For some reason, this can't be wxEventType, or VC++ complains.
    int m_eventType;            // main event type
    int m_id;                   // control/menu/toolbar id
    int m_lastId;               // used for ranges of ids
    wxObjectEventFunction m_fn; // function to call: not wxEventFunction,
                                // because of dependency problems

    wxObject* m_callbackUserData;
};

struct WXDLLIMPEXP_BASE wxEventTable
{
    const wxEventTable *baseTable;    // base event table (next in chain)
    const wxEventTableEntry *entries; // bottom of entry array
};

class WXDLLIMPEXP_BASE wxEventHashTable
{
//...
struct EventTypeTable
{
        wxEventType                   eventType; //事件类型
        wxEventTableEntryPointerArray eventEntryTable;  //事件条目指针数组
};

//...
protected:
    const wxEventTable    &m_table;   //事件表的引用，这里没有必要重建一份
    bool                   m_rebuildHash;  //开始时候哈希表并不建立，建立的时机发生了第一向上搜素时间表
    size_t                 m_size;//哈希表长度
    EventTypeTablePointer *m_eventTypeTable;//事件类型表指针数组

}

static const int EVENT_TYPE_TABLE_INIT_SIZE = 31; // Not too big not too small.

wxEventHashTable::wxEventHashTable(const wxEventTable &table)
                : m_table(table),
                  m_rebuildHash(true)
{
    AllocEventTypeTable(EVENT_TYPE_TABLE_INIT_SIZE);

    m_next = sm_first;
    if (m_next)
        m_next->m_previous = this;
    sm_first = this;
}

void wxEventHashTable::AllocEventTypeTable(size_t size)
{
    m_eventTypeTable = new EventTypeTablePointer[size];
    memset((void *)m_eventTypeTable, 0, sizeof(EventTypeTablePointer)*size);
    m_size = size;
}