學習 Message(17): WM_SYSCOMMAND 訊息[一]

已有定義的系統命令常數(感覺有些有問題):

SC_SIZE         = 61440;SC_MOVE         = 61456;SC_MINIMIZE     = 61472;SC_MAXIMIZE     = 61488;SC_NEXTWINDOW   = 61504;SC_PREVWINDOW   = 61520;SC_CLOSE        = 61536;SC_VSCROLL      = 61552;SC_HSCROLL      = 61568;SC_MOUSEMENU    = 61584;SC_KEYMENU      = 61696;SC_ARRANGE      = 61712;SC_RESTORE      = 61728;SC_TASKLIST     = 61744;SC_SCREENSAVE   = 61760;SC_HOTKEY       = 61776;SC_DEFAULT      = 61792;SC_MONITORPOWER = 61808;SC_CONTEXTHELP  = 61824;SC_SEPARATOR    = 61455;SC_ICON         = SC_MINIMIZE;SC_ZOOM         = SC_MAXIMIZE;

未定義的系統命令常數:

61441: 拖動左邊框61442: 拖動右邊框61443: 拖動上邊框61444: 拖動左上方61445: 拖動右上方61446: 拖動下邊框61447: 拖動左下角61448: 拖動右下角61458: 拖動標題列61558: 橫向捲軸滾動61574: 雙擊橫向捲軸61575: 縱向捲軸滾動61559: 雙擊縱向捲軸61587: 點擊最小化表徵圖61490: 在非最大化時雙擊標題列61730: 在最大化時雙擊標題列//可能還有...

WM_SYSCOMMAND 是做什麼的? 咱們先看看把 WM_SYSCOMMAND 訊息封鎖掉是什麼樣子吧:

代碼檔案:

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls;type  TForm1 = class(TForm)    Label1: TLabel;    procedure FormCreate(Sender: TObject);    procedure FormDblClick(Sender: TObject);  protected    procedure WMSysCommand(var Message: TWMSysCommand); message WM_SYSCOMMAND;  end;var  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);const  br = #13#10;begin  Label1.AutoSize := True;  Label1.Caption :=    '此表單屏蔽了 SYSCOMMAND 訊息!' + br +    '將無法改變表單大小;' + br +    '將無法移動表單;' + br +    '將無法最大、最小化表單;' + br +    '也將無法通過常規途徑關閉表單.' + br +    '' + br +    '所以提供了雙擊表單關閉的功能.';  Label1.OnDblClick := OnDblClick;end;procedure TForm1.FormDblClick(Sender: TObject);begin  Close;end;procedure TForm1.WMSysCommand(var Message: TWMSysCommand);begin//  inherited; {取消這句的注釋, WM_SysCommand 就活了}end;end.

表單檔案:

object Form1: TForm1  Left = 0  Top = 0  Caption = 'Form1'  ClientHeight = 172  ClientWidth = 264  Color = clBtnFace  Font.Charset = DEFAULT_CHARSET  Font.Color = clWindowText  Font.Height = -11  Font.Name = 'Tahoma'  Font.Style = []  OldCreateOrder = False  OnCreate = FormCreate  OnDblClick = FormDblClick  PixelsPerInch = 96  TextHeight = 13  object Label1: TLabel    Left = 24    Top = 24    Width = 89    Height = 33    Caption = 'Label1'  endend