学习 Message(9): 消息结构纵览

传递消息就是传递消息数据, 数据是一组数据, 所以消息是一个结构;
系统标准的消息结构在 Delphi 中被定义为 TMsg

---

PMsg = ^TMsg;

tagMSG = packed record

  hwnd: HWND;

  message: UINT;

  wParam: WPARAM;

  lParam: LPARAM;

  time: DWORD;

  pt: TPoint;

end;

TMsg = tagMSG;

MSG = tagMSG;


 
   

但 TMsg 和 VCL 中的更多消息结构如: TWMMouse、TWMKey 并不兼容;
但 TWMMouse、TWMKey 等都可以兼容: TMessage;
TMessage 是 VCL 重新定义的消息结构:

---

PMessage = ^TMessage;

TMessage = packed record

  Msg: Cardinal;

  case Integer of

    0: (

      WParam: WPARAM;

      LParam: LPARAM;

      Result: LRESULT);

    1: (

      WParamLo: Word;

      WParamHi: Word;

      LParamLo: Word;

      LParamHi: Word;

      ResultLo: Word;

      ResultHi: Word);

end;


 
   

有多少必要让 Delphi 不直接使用 TMsg 而非要有个 TMessage 呢?
我现在所能知道的: 1、简化; 2、增加返回值; 肯定还有其他理由, 望先者告诉我.
但我想不管怎样, VCL 最终肯定要回归 TMsg 的结构格式, 才能与系统打交道.

因为面对不同的消息, 消息参数的意义会完全不同;
在不同的消息里面, 有些参数也毫无意义, 可以省略;
另外, 有些消息参数非常抽象, 需要反复换算才得到我们容易理解的数据, 为什么不直接使用容易理解的数据呢?
所以 Delphi 定义了更多的消息结构:

---

TWMNoParams

TWMCancelMode       = TWMNoParams;

TWMChildActivate    = TWMNoParams;

TWMClear            = TWMNoParams;

TWMClose            = TWMNoParams;

TWMCopy             = TWMNoParams;

TWMCut              = TWMNoParams;

TWMDestroy          = TWMNoParams;

TWMDestroyClipboard = TWMNoParams;

TWMDrawClipboard    = TWMNoParams;

TWMFontChange       = TWMNoParams;

TWMGetDlgCode       = TWMNoParams;

TWMGetFont          = TWMNoParams;

TWMGetHotKey        = TWMNoParams;

TWMGetTextLength    = TWMNoParams;

TWMMDIGetActive     = TWMNoParams;

TWMMDIIconArrange   = TWMNoParams;

TWMMDIRefreshMenu   = TWMNoParams;

TWMNCDestroy        = TWMNoParams;

TWMPaintIcon        = TWMNoParams;

TWMPaste            = TWMNoParams;

TWMQueryDragIcon    = TWMNoParams;

TWMQueryNewPalette  = TWMNoParams;

TWMQueryOpen        = TWMNoParams;

TWMQueueSync        = TWMNoParams;

TWMRenderAllFormats = TWMNoParams;

TWMSysColorChange   = TWMNoParams;

TWMTimeChange       = TWMNoParams;

TWMQueryUIState     = TWMNoParams;

TWMUndo             = TWMNoParams;

TWMKey

TWMChar       = TWMKey;

TWMKeyDown    = TWMKey;

TWMKeyUp      = TWMKey;

TWMDeadChar   = TWMChar;

TWMSysChar    = TWMKey;

TWMSysKeyDown = TWMKey;

TWMSysKeyUp   = TWMKey;

TWMMouse

TWMLButtonDblClk = TWMMouse;

TWMLButtonDown   = TWMMouse;

TWMLButtonUp     = TWMMouse;

TWMMButtonDblClk = TWMMouse;

TWMMButtonDown   = TWMMouse;

TWMMButtonUp     = TWMMouse;

TWMMouseMove     = TWMMouse;

TWMRButtonDblClk = TWMMouse;

TWMRButtonDown   = TWMMouse;

TWMRButtonUp     = TWMMouse;

TWMMouseWheel

TMSHMouseWheel

TWMWindowPosMsg

TWMWindowPosChanged  = TWMWindowPosMsg;

TWMWindowPosChanging = TWMWindowPosMsg;

TWMScroll

TWMHScroll = TWMScroll;

TWMVScroll = TWMScroll;

TWMActivate

TWMActivateApp

TWMAskCBFormatName

TWMChangeCBChain

TWMCharToItem

TWMVKeyToItem = TWMCharToItem;

TWMChooseFont_GetLogFont

TWMCommand

TWMCompacting

TWMCompareItem

TWMCopyData

TWMCreate

TWMCtlColor

TWMCtlColorBtn       = TWMCtlColor;

TWMCtlColorDlg       = TWMCtlColor;

TWMCtlColorEdit      = TWMCtlColor;

TWMCtlColorListbox   = TWMCtlColor;

TWMCtlColorMsgbox    = TWMCtlColor;

TWMCtlColorScrollbar = TWMCtlColor;

TWMCtlColorStatic    = TWMCtlColor;

TWMDDE_Ack

TWMDDE_Advise

TWMDDE_Data

TWMDDE_Execute

TWMDDE_Initiate

TWMDDE_Poke

TWMDDE_Request

TWMDDE_Terminate

TWMDDE_Unadvise

TWMDeleteItem

TWMDevModeChange

TWMDrawItem

TWMDropFiles

TWMEnable

TWMEndSession

TWMEnterIdle

TWMEnterMenuLoop

TWMExitMenuLoop = TWMEnterMenuLoop;

TWMEraseBkgnd

TWMGetIcon

TWMGetMinMaxInfo

TWMGetText

TWMHotKey

TWMHScrollClipboard

TWMIconEraseBkgnd = TWMEraseBkgnd;

TWMInitDialog

TWMInitMenu

TWMInitMenuPopup

TWMKillFocus

TWMMDIActivate

TWMMDICascade

TWMMDICreate

TWMMDIDestroy

TWMMDIMaximize

TWMMDINext

TWMMDIRestore

TWMMDISetMenu

TWMMDITile

TWMMeasureItem

TWMMenuChar

TWMMenuSelect

TWMMouseActivate

TWMMove

TWMMoving

TWMNCActivate

TWMNCCalcSize

TWMNCCreate

TWMNCHitTest

TWMNCHitMessage

TWMNCLButtonDblClk = TWMNCHitMessage;

TWMNCLButtonDown   = TWMNCHitMessage;

TWMNCLButtonUp     = TWMNCHitMessage;

TWMNCMButtonDblClk = TWMNCHitMessage;

TWMNCMButtonDown   = TWMNCHitMessage;

TWMNCMButtonUp     = TWMNCHitMessage;

TWMNCMouseMove     = TWMNCHitMessage;

TWMNCRButtonDblClk = TWMNCHitMessage;

TWMNCRButtonDown   = TWMNCHitMessage;

TWMNCRButtonUp     = TWMNCHitMessage;

TWMNCPaint

TWMNextDlgCtl

TWMNotify

TWMNotifyFormat

TWMPaint

TWMPaintClipboard

TWMPaletteChanged

TWMPaletteIsChanging

TWMParentNotify

TWMPower

TWMQueryEndSession

TWMQuit

TWMRenderFormat

TWMSetCursor

TWMSetFocus

TWMSetFont

TWMSetHotKey

TWMSetIcon

TWMSetRedraw

TWMSetText

TWMShowWindow

TWMSize

TWMSizeClipboard

TWMSpoolerStatus

TWMStyleChange

TWMStyleChanged  = TWMStyleChange;

TWMStyleChanging = TWMStyleChange;

TWMSysCommand

TWMSysDeadChar

TWMSystemError

TWMTimer

TWMUIState

TWMChangeUIState = TWMUIState;

TWMUpdateUIState = TWMUIState;

TWMVScrollClipboard

TWMWinIniChange

TWMSettingChange

TWMHelp

TWMDisplayChange

TWMContextMenu

TWMPrint

TWMPrintClient = TWMPrint;


 
   

这样做的目的, 无非就是为了理解与简捷. 但为什么会有那么多重命名(说明它们的参数结构相同)呢?
我想 Delphi 这样做可能是为了和消息一一对应吧, 譬如: WM_LButtonDown 消息对应 TWMLButtonDown 结构. 这样根据命名规则, 可以方便地通过消息名称方便地找到对应的消息结构.

TMessage 在 VCL 中是通用的, 它可以代替其中任何一个.

另外, 这会是 Windows 消息的全部吗?
我想肯定不是, 就像 API 函数一样, 它们在不断地增加, 况且还有那么多的自定义消息, 这应该只是一些常用的, 也够多了.

---