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.