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Messages.pas里的消息
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一、Windows 消息大全
这张表拷贝自万一兄的帖子：http://www.cnblogs.com/del/archive/2008/02/25/1079970.html
但是我希望自己能把这些消息的注释都写上。特别简单的消息就不写了（否则反而无法一目了然），只写对我自己觉得值得注意的消息。我也没有整块的时间，有时间就每天写几个注释，就当是自己学习了。
说到底，常用的Windows消息就这么多，共233个，全部了解清楚的话对编程是很有帮助的。Win32标准控件的消息更是有限的。
二、Delphi 也自定义了一些消息, 分别是 CM_ 和 CN_ 打头。
三、常用问题：
1、参数wParam、lParam这2个参数有什么区别？
Delphi 就是把这两个消息参数重整为一个结构体，但对不同的消息, 消息参数的意义是不同的, 尽管有些规律但区别也很大。如果你能弄明白消息参数在每个消息中的不同意义, Windows 编程就算学会了大半了，事实上, 除了常用的消息外, 大部分消息都是即查(msdn 或 api 手册)即用：
Microsoft Win32 程序员参考大全(五) - 消息、结构和宏
参考：http://msdn.microsoft.com/zh-cn/library/
2、Perform、SendMessage、PostMessage的区别？
Perform、SendMessage会直接发送消息到窗体过程，PostMessage 是把消息放入消息队列。
因为 Application.OnMessage 只接收队列中的消息，所以 Perform、SendMessage 发送的消息, OnMessage 收不到。
Perform 和上面两个不同, 它是控件的一个方法, TControl 的子孙都有这个方法, TControl 之上的父类们不需要处理消息, 也没有消息要处理。
参考：http://www.cnblogs.com/del/archive/2008/10/28/1321490.html
3、TApplicationEvents.OnMessage 的第二个参数是什么意思：
参考：http://www.cnblogs.com/del/archive/2008/10/25/1319318.html
4、消息的发送过程：
参考：http://www.cnblogs.com/del/archive/2008/10/24/1318897.html
5、同一个消息可以有三个函数都响应它，但是它们是有先后顺序的：
参考：http://www.cnblogs.com/del/archive/2008/10/24/1319062.html
6、Delphi 7里Messages.pas里所有消息。
经统计，共104种重定义消息种类，方便使用，180种不同的消息名称。省得像VC里一样，处处自己解析wParam和LParam参数进行分析。有空我要把它们一个一个标注和学习一下。另外要强调一点：Delphi里所有的消息都没有包含Handle，Handle本身不是消息的一部分（VC里也是这样），除非有些消息要用到2个Handle。但是注意，另有TMsg结构，定义在windows.pas文件里。除此之外，还定义有 TEventMsg TCreateStruct 等许多结构，都是需要学习和注意的地方。
tagMSG = packed record
hwnd: HWND;
message: UINT;
wParam: WPARAM;
lParam: LPARAM;
time: DWORD;
pt: TPoint;
end;
TMsg = tagMSG;
// ====================正文开始======================================
PMessage = ^TMessage;
TMessage = packed record
Msg: Cardinal; // 无论什么消息，第一个成员都是消息编号（消息字符串名称所对应的编号）
case Integer of
0: (
WParam: Longint;
LParam: Longint;
Result: Longint); // 返回值
1: (
WParamLo: Word;
WParamHi: Word;
LParamLo: Word;
LParamHi: Word;
ResultLo: Word; // 返回值
ResultHi: Word);
end;
{ Common message format records }
// 无论消息怎么重定义，总长度都是4个integer
TWMNoParams = packed record
Msg: Cardinal;
Unused: array[0..3] of Word;
Result: Longint;
end;
TWMKey = packed record // 按键
Msg: Cardinal;
CharCode: Word;
Unused: Word;
KeyData: Longint;
Result: Longint;
end;
TWMMouse = packed record // 鼠标
Msg: Cardinal;
Keys: Longint;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TWMMouseWheel = packed record // 鼠标滚轮
Msg: Cardinal;
Keys: SmallInt;
WheelDelta: SmallInt;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TMSHMouseWheel = packed record // MS鼠标滚轮
Msg: Cardinal;
WheelDelta: Integer;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TWMWindowPosMsg = packed record // 窗口位置
Msg: Cardinal;
Unused: Integer;
WindowPos: PWindowPos;
Result: Longint;
end;
TWMScroll = packed record // 滚动条消息
Msg: Cardinal;
ScrollCode: Smallint; { SB_xxxx }
Pos: Smallint;
ScrollBar: HWND;
Result: Longint;
end;
{ Message records }
TWMActivate = packed record
Msg: Cardinal;
Active: Word; { WA_INACTIVE, WA_ACTIVE, WA_CLICKACTIVE }
Minimized: WordBool;
ActiveWindow: HWND;
Result: Longint;
end;
TWMActivateApp = packed record
Msg: Cardinal;
Active: BOOL;
ThreadId: Longint;
Result: Longint;
end;
TWMAskCBFormatName = packed record
Msg: Cardinal;
NameLen: Word;
Unused: Word;
FormatName: PChar;
Result: Longint;
end;
TWMCancelMode = TWMNoParams;
TWMChangeCBChain = packed record // 难道是Hook消息？
Msg: Cardinal;
Remove: HWND;
Next: HWND;
Result: Longint;
end;
TWMChar = TWMKey;
TWMCharToItem = packed record
Msg: Cardinal;
Key: Word;
CaretPos: Word;
ListBox: HWND;
Result: Longint;
end;
TWMChildActivate = TWMNoParams;
TWMChooseFont_GetLogFont = packed record
Msg: Cardinal;
Unused: Longint;
LogFont: PLogFont;
Result: Longint;
end;
TWMClear = TWMNoParams;
TWMClose = TWMNoParams;
TWMCommand = packed record
Msg: Cardinal;
ItemID: Word;
NotifyCode: Word;
Ctl: HWND;
Result: Longint;
end;
TWMCompacting = packed record
Msg: Cardinal;
CompactRatio: Longint;
Unused: Longint;
Result: Longint;
end;
TWMCompareItem = packed record
Msg: Cardinal;
Ctl: HWnd;
CompareItemStruct: PCompareItemStruct;
Result: Longint;
end;
TWMCopy = TWMNoParams;
TWMCopyData = packed record
Msg: Cardinal;
From: HWND;
CopyDataStruct: PCopyDataStruct;
Result: Longint;
end;
{ ?? WM_CLP_LAUNCH, WM_CPL_LAUNCHED }
TWMCreate = packed record
Msg: Cardinal;
Unused: Integer;
CreateStruct: PCreateStruct;
Result: Longint;
end;
TWMCtlColor = packed record
Msg: Cardinal;
ChildDC: HDC;
ChildWnd: HWND;
Result: Longint;
end;
TWMCtlColorBtn = TWMCtlColor;
TWMCtlColorDlg = TWMCtlColor;
TWMCtlColorEdit = TWMCtlColor;
TWMCtlColorListbox = TWMCtlColor;
TWMCtlColorMsgbox = TWMCtlColor;
TWMCtlColorScrollbar = TWMCtlColor;
TWMCtlColorStatic = TWMCtlColor;
TWMCut = TWMNoParams;
TWMDDE_Ack = packed record
Msg: Cardinal;
PostingApp: HWND;
case Word of
WM_DDE_INITIATE: (
App: Word;
Topic: Word;
Result: Longint);
WM_DDE_EXECUTE {and all others}: (
PackedVal: Longint);
end;
TWMDDE_Advise = packed record
Msg: Cardinal;
PostingApp: HWND;
PackedVal: Longint;
Result: Longint;
end;
TWMDDE_Data = packed record
Msg: Cardinal;
PostingApp: HWND;
PackedVal: Longint;
Result: Longint;
end;
TWMDDE_Execute = packed record
Msg: Cardinal;
PostingApp: HWND;
Commands: THandle;
Result: Longint;
end;
TWMDDE_Initiate = packed record
Msg: Cardinal;
PostingApp: HWND;
App: Word;
Topic: Word;
Result: Longint;
end;
TWMDDE_Poke = packed record
Msg: Cardinal;
PostingApp: HWND;
PackedVal: Longint;
Result: Longint;
end;
TWMDDE_Request = packed record
Msg: Cardinal;
PostingApp: HWND;
Format: Word;
Item: Word;
Result: Longint;
end;
TWMDDE_Terminate = packed record
Msg: Cardinal;
PostingApp: HWND;
Unused: Longint;
Result: Longint;
end;
TWMDDE_Unadvise = packed record
Msg: Cardinal;
PostingApp: HWND;
Format: Word;
Item: Word;
Result: Longint;
end;
TWMDeadChar = TWMChar;
TWMDeleteItem = packed record
Msg: Cardinal;
Ctl: HWND;
DeleteItemStruct: PDeleteItemStruct;
Result: Longint;
end;
TWMDestroy = TWMNoParams;
TWMDestroyClipboard = TWMNoParams;
TWMDevModeChange = packed record
Msg: Cardinal;
Unused: Integer;
Device: PChar;
Result: Longint;
end;
TWMDrawClipboard = TWMNoParams;
TWMDrawItem = packed record
Msg: Cardinal;
Ctl: HWND;
DrawItemStruct: PDrawItemStruct;
Result: Longint;
end;
TWMDropFiles = packed record
Msg: Cardinal;
Drop: THANDLE;
Unused: Longint;
Result: Longint;
end;
TWMEnable = packed record
Msg: Cardinal;
Enabled: LongBool;
Unused: Longint;
Result: Longint;
end;
TWMEndSession = packed record
Msg: Cardinal;
EndSession: LongBool;
Unused: Longint;
Result: Longint;
end;
TWMEnterIdle = packed record
Msg: Cardinal;
Source: Longint; { MSGF_DIALOGBOX, MSGF_MENU }
IdleWnd: HWND;
Result: Longint;
end;
TWMEnterMenuLoop = packed record
Msg: Cardinal;
IsTrackPopupMenu: LongBool;
Unused: Longint;
Result: Longint;
end;
TWMExitMenuLoop = TWMEnterMenuLoop;
TWMEraseBkgnd = packed record // 擦除背景
Msg: Cardinal;
DC: HDC; // 已经含有DC句柄了
Unused: Longint;
Result: Longint;
end;
TWMFontChange = TWMNoParams;
TWMGetDlgCode = TWMNoParams;
TWMGetFont = TWMNoParams;
TWMGetIcon = packed record
Msg: Cardinal;
BigIcon: Longbool;
Unused: Longint;
Result: Longint;
end;
TWMGetHotKey = TWMNoParams;
TWMGetMinMaxInfo = packed record
Msg: Cardinal;
Unused: Integer;
MinMaxInfo: PMinMaxInfo;
Result: Longint;
end;
TWMGetText = packed record
Msg: Cardinal;
TextMax: Integer;
Text: PChar;
Result: Longint;
end;
TWMGetTextLength = TWMNoParams;
TWMHotKey = packed record
Msg: Cardinal;
HotKey: Longint;
Unused: Longint;
Result: Longint;
end;
TWMHScroll = TWMScroll;
TWMHScrollClipboard = packed record
Msg: Cardinal;
Viewer: HWND;
ScrollCode: Word; {SB_BOTTOM, SB_ENDSCROLL, SB_LINEDOWN, SB_LINEUP,
SB_PAGEDOWN, SB_PAGEUP, SB_THUMBPOSITION,
SB_THUMBTRACK, SB_TOP }
Pos: Word;
Result: Longint;
end;
TWMIconEraseBkgnd = TWMEraseBkgnd;
TWMInitDialog = packed record
Msg: Cardinal;
Focus: HWND;
InitParam: Longint;
Result: Longint;
end;
TWMInitMenu = packed record
Msg: Cardinal;
Menu: HMENU;
Unused: Longint;
Result: Longint;
end;
TWMInitMenuPopup = packed record
Msg: Cardinal;
MenuPopup: HMENU;
Pos: Smallint;
SystemMenu: WordBool;
Result: Longint;
end;
TWMKeyDown = TWMKey;
TWMKeyUp = TWMKey;
TWMKillFocus = packed record
Msg: Cardinal;
FocusedWnd: HWND;
Unused: Longint;
Result: Longint;
end;
TWMLButtonDblClk = TWMMouse;
TWMLButtonDown = TWMMouse;
TWMLButtonUp = TWMMouse;
TWMMButtonDblClk = TWMMouse;
TWMMButtonDown = TWMMouse;
TWMMButtonUp = TWMMouse;
TWMMDIActivate = packed record
Msg: Cardinal;
case Integer of
0: (
ChildWnd: HWND);
1: (
DeactiveWnd: HWND;
ActiveWnd: HWND;
Result: Longint);
end;
TWMMDICascade = packed record
Msg: Cardinal;
Cascade: Longint; { 0, MDITILE_SKIPDISABLED }
Unused: Longint;
Result: Longint;
end;
TWMMDICreate = packed record
Msg: Cardinal;
Unused: Integer;
MDICreateStruct: PMDICreateStruct;
Result: Longint;
end;
TWMMDIDestroy = packed record
Msg: Cardinal;
Child: HWND;
Unused: Longint;
Result: Longint;
end;
TWMMDIGetActive = TWMNoParams;
TWMMDIIconArrange = TWMNoParams;
TWMMDIMaximize = packed record
Msg: Cardinal;
Maximize: HWND;
Unused: Longint;
Result: Longint;
end;
TWMMDINext = packed record
Msg: Cardinal;
Child: HWND;
Next: Longint;
Result: Longint;
end;
TWMMDIRefreshMenu = TWMNoParams;
TWMMDIRestore = packed record
Msg: Cardinal;
IDChild: HWND;
Unused: Longint;
Result: Longint;
end;
TWMMDISetMenu = packed record
Msg: Cardinal;
MenuFrame: HMENU;
MenuWindow: HMENU;
Result: Longint;
end;
TWMMDITile = packed record
Msg: Cardinal;
Tile: Longint; { MDITILE_HORIZONTAL, MDITILE_SKIPDISABLE,
MDITILE_VERTICAL }
Unused: Longint;
Result: Longint;
end;
TWMMeasureItem = packed record
Msg: Cardinal;
IDCtl: HWnd;
MeasureItemStruct: PMeasureItemStruct;
Result: Longint;
end;
TWMMenuChar = packed record
Msg: Cardinal;
User: Char;
Unused: Byte;
MenuFlag: Word; { MF_POPUP, MF_SYSMENU }
Menu: HMENU;
Result: Longint;
end;
TWMMenuSelect = packed record
Msg: Cardinal;
IDItem: Word;
MenuFlag: Word; { MF_BITMAP, MF_CHECKED, MF_DISABLED, MF_GRAYED,
MF_MOUSESELECT, MF_OWNERDRAW, MF_POPUP, MF_SEPARATOR,
MF_SYSMENU }
Menu: HMENU;
Result: Longint;
end;
TWMMouseActivate = packed record
Msg: Cardinal;
TopLevel: HWND;
HitTestCode: Word;
MouseMsg: Word;
Result: Longint;
end;
TWMMouseMove = TWMMouse;
TWMMove = packed record
Msg: Cardinal;
Unused: Integer;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TWMMoving = packed record
Msg: Cardinal;
Edge: Integer;
DragRect: PRect;
end;
TWMNCActivate = packed record
Msg: Cardinal;
Active: BOOL;
Unused: Longint;
Result: Longint;
end;
TWMNCCalcSize = packed record
Msg: Cardinal;
CalcValidRects: BOOL;
CalcSize_Params: PNCCalcSizeParams;
Result: Longint;
end;
TWMNCCreate = packed record
Msg: Cardinal;
Unused: Integer;
CreateStruct: PCreateStruct;
Result: Longint;
end;
TWMNCDestroy = TWMNoParams;
TWMNCHitTest = packed record
Msg: Cardinal;
Unused: Longint;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TWMNCHitMessage = packed record
Msg: Cardinal;
HitTest: Longint;
XCursor: Smallint;
YCursor: Smallint;
Result: Longint;
end;
TWMNCLButtonDblClk = TWMNCHitMessage;
TWMNCLButtonDown = TWMNCHitMessage;
TWMNCLButtonUp = TWMNCHitMessage;
TWMNCMButtonDblClk = TWMNCHitMessage;
TWMNCMButtonDown = TWMNCHitMessage;
TWMNCMButtonUp = TWMNCHitMessage;
TWMNCMouseMove = TWMNCHitMessage;
TWMNCPaint = packed record
Msg: Cardinal;
RGN: HRGN;
Unused: Longint;
Result: Longint;
end;
TWMNCRButtonDblClk = TWMNCHitMessage;
TWMNCRButtonDown = TWMNCHitMessage;
TWMNCRButtonUp = TWMNCHitMessage;
TWMNextDlgCtl = packed record
Msg: Cardinal;
CtlFocus: Longint;
Handle: WordBool;
Unused: Word;
Result: Longint;
end;
TWMNotify = packed record
Msg: Cardinal;
IDCtrl: Longint;
NMHdr: PNMHdr;
Result: Longint;
end;
TWMNotifyFormat = packed record
Msg: Cardinal;
From: HWND;
Command: Longint;
Result: Longint;
end;
TWMPaint = packed record
Msg: Cardinal;
DC: HDC;
Unused: Longint;
Result: Longint;
end;
TWMPaintClipboard = packed record
Msg: Cardinal;
Viewer: HWND;
PaintStruct: THandle;
Result: Longint;
end;
TWMPaintIcon = TWMNoParams;
TWMPaletteChanged = packed record
Msg: Cardinal;
PalChg: HWND;
Unused: Longint;
Result: Longint;
end;
TWMPaletteIsChanging = packed record
Msg: Cardinal;
Realize: HWND;
Unused: Longint;
Result: Longint;
end;
TWMParentNotify = packed record
Msg: Cardinal;
case Event: Word of
WM_CREATE, WM_DESTROY: (
ChildID: Word;
ChildWnd: HWnd);
WM_LBUTTONDOWN, WM_MBUTTONDOWN, WM_RBUTTONDOWN: (
Value: Word;
XPos: Smallint;
YPos: Smallint);
0: (
Value1: Word;
Value2: Longint;
Result: Longint);
end;
TWMPaste = TWMNoParams;
TWMPower = packed record
Msg: Cardinal;
PowerEvt: Longint; { PWR_SUSPENDREQUEST, PWR_SUSPENDRESUME,
PWR_CRITICALRESUME }
Unused: Longint;
Result: Longint;
end;
TWMQueryDragIcon = TWMNoParams;
TWMQueryEndSession = packed record
Msg: Cardinal;
Source: Longint;
Unused: Longint;
Result: Longint;
end;
TWMQueryNewPalette = TWMNoParams;
TWMQueryOpen = TWMNoParams;
TWMQueueSync = TWMNoParams;
TWMQuit = packed record
Msg: Cardinal;
ExitCode: Longint;
Unused: Longint;
Result: Longint;
end;
TWMRButtonDblClk = TWMMouse;
TWMRButtonDown = TWMMouse;
TWMRButtonUp = TWMMouse;
TWMRenderAllFormats = TWMNoParams;
TWMRenderFormat = packed record
Msg: Cardinal;
Format: Longint;
Unused: Longint;
Result: Longint;
end;
TWMSetCursor = packed record
Msg: Cardinal;
CursorWnd: HWND;
HitTest: Word;
MouseMsg: Word;
Result: Longint;
end;
TWMSetFocus = packed record
Msg: Cardinal;
FocusedWnd: HWND;
Unused: Longint;
Result: Longint;
end;
TWMSetFont = packed record
Msg: Cardinal;
Font: HFONT;
Redraw: WordBool;
Unused: Word;
Result: Longint;
end;
TWMSetHotKey = packed record
Msg: Cardinal;
Key: Longint;
Unused: Longint;
Result: Longint;
end;
TWMSetIcon = packed record
Msg: Cardinal;
BigIcon: Longbool;
Icon: HICON;
Result: Longint;
end;
TWMSetRedraw = packed record
Msg: Cardinal;
Redraw: Longint;
Unused: Longint;
Result: Longint;
end;
TWMSetText = packed record
Msg: Cardinal;
Unused: Longint;
Text: PChar;
Result: Longint;
end;
TWMShowWindow = packed record
Msg: Cardinal;
Show: BOOL;
Status: Longint;
Result: Longint;
end;
TWMSize = packed record
Msg: Cardinal;
SizeType: Longint; { SIZE_MAXIMIZED, SIZE_MINIMIZED, SIZE_RESTORED,
SIZE_MAXHIDE, SIZE_MAXSHOW }
Width: Word;
Height: Word;
Result: Longint;
end;
TWMSizeClipboard = packed record
Msg: Cardinal;
Viewer: HWND;
RC: THandle;
Result: Longint;
end;
TWMSpoolerStatus = packed record
Msg: Cardinal;
JobStatus: Longint;
JobsLeft: Word;
Unused: Word;
Result: Longint;
end;
TWMStyleChange = packed record
Msg: Cardinal;
StyleType: Longint;
StyleStruct: PStyleStruct;
Result: Longint;
end;
TWMStyleChanged = TWMStyleChange;
TWMStyleChanging = TWMStyleChange;
TWMSysChar = TWMKey;
TWMSysColorChange = TWMNoParams;
TWMSysCommand = packed record
Msg: Cardinal;
case CmdType: Longint of
SC_HOTKEY: (ActivateWnd: HWND);
SC_KEYMENU: (Key: Word);
// 13种系统消息，另外热键和菜单消息
SC_CLOSE, SC_HSCROLL, SC_MAXIMIZE, SC_MINIMIZE, SC_MOUSEMENU, SC_MOVE,
SC_NEXTWINDOW, SC_PREVWINDOW, SC_RESTORE, SC_SCREENSAVE, SC_SIZE,
SC_TASKLIST, SC_VSCROLL: (
XPos: Smallint;
YPos: Smallint;
Result: Longint);
end;
TWMSysDeadChar = packed record
Msg: Cardinal;
CharCode: Word;
Unused: Word;
KeyData: Longint;
Result: Longint;
end;
TWMSysKeyDown = TWMKey;
TWMSysKeyUp = TWMKey;
TWMSystemError = packed record
Msg: Cardinal;
ErrSpec: Word;
Unused: Longint;
Result: Longint;
end;
TWMTimeChange = TWMNoParams;
TWMTimer = packed record
Msg: Cardinal;
TimerID: Longint;
TimerProc: TFarProc;
Result: Longint;
end;
TWMUIState = packed record
Msg: Cardinal;
Action: Word;
Flags: Word;
Unused: Longint;
end;
TWMChangeUIState = TWMUIState;
TWMUpdateUIState = TWMUIState;
TWMQueryUIState = TWMNoParams;
TWMUndo = TWMNoParams;
TWMVKeyToItem = TWMCharToItem;
TWMVScroll = TWMScroll;
TWMVScrollClipboard = packed record
Msg: Cardinal;
Viewer: HWND;
ScollCode: Word;
ThumbPos: Word;
Result: Longint;
end;
TWMWindowPosChanged = TWMWindowPosMsg;
TWMWindowPosChanging = TWMWindowPosMsg;
TWMWinIniChange = packed record
Msg: Cardinal;
Unused: Integer;
Section: PChar;
Result: Longint;
end;
TWMSettingChange = packed record
Msg: Cardinal;
Flag: Integer;
Section: PChar;
Result: Longint;
end;
TWMHelp = packed record
Msg: Cardinal;
Unused: Integer;
HelpInfo: PHelpInfo;
Result: Longint;
end;
TWMDisplayChange = packed record
Msg: Cardinal;
BitsPerPixel: Integer;
Width: Word;
Height: Word;
Result: Longint;
end;
TWMContextMenu = packed record
Msg: Cardinal;
hWnd: HWND;
case Integer of
0: (
XPos: Smallint;
YPos: Smallint);
1: (
Pos: TSmallPoint;
Result: Longint);
end;
TWMPrint = packed record
Msg: Cardinal;
DC: HDC;
Flags: Cardinal;
Result: Integer;
end;
TWMPrintClient = TWMPrint;
-----------------------------------------------------------------------------------------------------
RegisterWindowMessage：
RegisterWindowMessage用于在windows系统中注册一个唯一的消息。如果注册成功时，直接返回消息号，消息号的范围在 0xC000 (3072) 到 0xFFFF (65535) 之间。如果注册失败时，则该函数返回 0。
注意：当以字符串所标识的消息存在时，则直接返回该字符串所对应的消息号。
