Delphi一共封装（超类化）了8种Windows基础控件和17种复杂控件
超类化源码：
procedure TWinControl.CreateSubClass(var Params: TCreateParams; ControlClassName: PChar); const {CS_OWNDC标志，属于此窗口类的窗口实例都有自己的DC(称为私有DC) } {CS_CLASSDC标志，所有属于该类的窗口实例共享相同的DC（称为类DC）.类DC有一些私有DC的优点，而更加节约内存} {CS_PARENTDC标志，属于这个类的窗口都使用它的父窗口的句柄。和CS_CLASSDC相似的是，多个窗口共享一个DC，不同的是，这多个窗口（虽然有父子关系并且共享DC）并不要求都属于同一个窗口类} {CS_GLOBALCLASS标志，是唯一一个针对类本身起作用而不是对单个窗口起作用的标志。} CS_OFF = CS_OWNDC or CS_CLASSDC or CS_PARENTDC or CS_GLOBALCLASS; {CS_HREDRAW和CS_VREDRAW标志表示当窗口的水平尺寸（宽度）改变的时候，重画整个窗口。按钮和滚动条都有这两种风格。} CS_ON = CS_VREDRAW or CS_HREDRAW; var SaveInstance: THandle; begin // 说是子类化，其实是超类化 // http://www.cnblogs.com/findumars/p/4121704.html Delphi对Button的超类化 // http://www.cnblogs.com/findumars/p/4680601.html 子类化是窗口实例级别的，超类化是在窗口类（WNDCLASS）级别的 // http://www.cnblogs.com/sfqh/p/3384457.html 探索Win32系统之窗口类 // important 两个参数：Windows类的风格，类名（Windows的内置类） // Creates a windowed control derived from an existing Windows window class. // CreateSubClass allows VCL controls to create registered Windows controls. // 问题：不明白，哪里创建新类了。回答：根据已有的Windows类，创建Windows控件，注意是控件，不是类。 // 此单元没有调用此函数，但TButton，TEdit，TCombobox 等等都调用了它。 if ControlClassName <> nil then // 如果类名不为空 with Params do // 它是可变参数，结构体Params.WindowClass begin // 记录当前Windows类的句柄实例（其实是整个EXE模块的句柄） SaveInstance := WindowClass.hInstance; // API取得相关信息(第三个参数)。 失败返回0 // 只有三次执行都失败（2个句柄，一个类名），条件才成立。也就是这个ControlClassName新类还没有在内存中注册过。 if not GetClassInfo(HInstance, ControlClassName, WindowClass) and // API 取得信息填充，第一个参数是Application.Instance(全局变量)，第二个参数是类名，第三个参数等待填充的结构，即Params.WindowClass not GetClassInfo(0, ControlClassName, WindowClass) and // not GetClassInfo(MainInstance, ControlClassName, WindowClass) // MainInstance就这一处，标识EXE文件的Instance（系统级全局变量） then // 根据句柄和名称得到WindowClass的所有信息，注意，有可能覆盖了原先的hInstance，所以要事先记录，事后赋值 GetClassInfo(WindowClass.hInstance, ControlClassName, WindowClass); // API，第三个参数是Out // 一旦发现类名注册过了，就什么都不用做 // 为了保险起见，除了EXE模块句柄不得不重新赋值以外，其它一切旧有记录信息从Windows内核中直接取出。连类名都有可能被改变。 // fixme TButton调用了它，应该跟踪一下。 WindowClass.hInstance := SaveInstance; // 改变风格标记，不希望自绘，并且窗口大小或位置改变后，就重绘整个窗口 // 注意，TEdit等等都是直接继承自TWinControl，没有自绘句柄。 WindowClass.style := WindowClass.style and not CS_OFF or CS_ON; // fixme 抛弃一切DC，准备使用Delphi体系的Canvas进行自绘。 // 问题：执行以后，类名到底是TButton还是Button？ // important 取到的信息，都通过Params.WindowClass传出去 end; end;
8种Windows基础控件：
"G:\Vcl\StdCtrls.pas"(1898,3): CreateSubClass(Params, 'EDIT'); "G:\Vcl\StdCtrls.pas"(2986,3): CreateSubClass(Params, 'COMBOBOX'); "G:\Vcl\StdCtrls.pas"(3512,3): CreateSubClass(Params, 'BUTTON'); // TButton "G:\Vcl\StdCtrls.pas"(3658,3): CreateSubClass(Params, 'BUTTON'); // TCustomCheckBox "G:\Vcl\StdCtrls.pas"(3783,3): CreateSubClass(Params, 'BUTTON'); // TRadioButton "G:\Vcl\StdCtrls.pas"(4369,3): CreateSubClass(Params, 'LISTBOX'); "G:\Vcl\StdCtrls.pas"(4783,3): CreateSubClass(Params, 'SCROLLBAR'); "G:\Vcl\StdCtrls.pas"(4984,3): CreateSubClass(Params, 'STATIC');
17种Windows复杂控件：
"G:\Vcl\ComCtrls.pas"(11434,3): CreateSubClass(Params, 'RICHEDIT'); "G:\Vcl\ComCtrls.pas"(4263,3): CreateSubClass(Params, WC_TABCONTROL); "G:\Vcl\ComCtrls.pas"(5604,3): CreateSubClass(Params, STATUSCLASSNAME); "G:\Vcl\ComCtrls.pas"(6268,3): CreateSubClass(Params, WC_HEADER); "G:\Vcl\ComCtrls.pas"(8410,3): CreateSubClass(Params, WC_TREEVIEW); "G:\Vcl\ComCtrls.pas"(10039,3): CreateSubClass(Params, TRACKBAR_CLASS); "G:\Vcl\ComCtrls.pas"(10376,3): CreateSubClass(Params, PROGRESS_CLASS); "G:\Vcl\ComCtrls.pas"(11856,3): CreateSubClass(Params, UPDOWN_CLASS); "G:\Vcl\ComCtrls.pas"(12181,3): CreateSubClass(Params, HOTKEYCLASS); "G:\Vcl\ComCtrls.pas"(13593,3): CreateSubClass(Params, WC_LISTVIEW); "G:\Vcl\ComCtrls.pas"(15775,3): CreateSubClass(Params, ANIMATE_CLASS); "G:\Vcl\ComCtrls.pas"(16837,3): CreateSubClass(Params, TOOLBARCLASSNAME); "G:\Vcl\ComCtrls.pas"(19840,3): CreateSubClass(Params, REBARCLASSNAME); "G:\Vcl\ComCtrls.pas"(21313,3): CreateSubClass(Params, MONTHCAL_CLASS); "G:\Vcl\ComCtrls.pas"(21421,3): CreateSubClass(Params, DATETIMEPICK_CLASS); "G:\Vcl\ComCtrls.pas"(21691,3): CreateSubClass(Params, WC_PAGESCROLLER); "G:\Vcl\ComCtrls.pas"(22175,3): CreateSubClass(Params, WC_COMBOBOXEX);
本着任何技术都要烂熟于心的精神，把8种基础控件的代码贴上来，混个脸熟，以后再加上注释：
procedure TCustomEdit.CreateParams(var Params: TCreateParams); const Passwords: array[Boolean] of DWORD = (0, ES_PASSWORD); ReadOnlys: array[Boolean] of DWORD = (0, ES_READONLY); CharCases: array[TEditCharCase] of DWORD = (0, ES_UPPERCASE, ES_LOWERCASE); HideSelections: array[Boolean] of DWORD = (ES_NOHIDESEL, 0); OEMConverts: array[Boolean] of DWORD = (0, ES_OEMCONVERT); begin inherited CreateParams(Params); CreateSubClass(Params, 'EDIT'); with Params do begin Style := Style or (ES_AUTOHSCROLL or ES_AUTOVSCROLL) or BorderStyles[FBorderStyle] or Passwords[FPasswordChar <> #0] or ReadOnlys[FReadOnly] or CharCases[FCharCase] or HideSelections[FHideSelection] or OEMConverts[FOEMConvert]; if NewStyleControls and Ctl3D and (FBorderStyle = bsSingle) then begin Style := Style and not WS_BORDER; ExStyle := ExStyle or WS_EX_CLIENTEDGE; end; end; end; procedure TCustomComboBox.CreateParams(var Params: TCreateParams); const ComboBoxStyles: array[TComboBoxStyle] of DWORD = ( CBS_DROPDOWN, CBS_SIMPLE, CBS_DROPDOWNLIST, CBS_DROPDOWNLIST or CBS_OWNERDRAWFIXED, CBS_DROPDOWNLIST or CBS_OWNERDRAWVARIABLE); CharCases: array[TEditCharCase] of DWORD = (0, CBS_UPPERCASE, CBS_LOWERCASE); Sorts: array[Boolean] of DWORD = (0, CBS_SORT); begin inherited CreateParams(Params); CreateSubClass(Params, 'COMBOBOX'); with Params do Style := Style or (WS_VSCROLL or CBS_HASSTRINGS or CBS_AUTOHSCROLL) or ComboBoxStyles[FStyle] or Sorts[FSorted] or CharCases[FCharCase]; end; procedure TButton.CreateParams(var Params: TCreateParams); const ButtonStyles: array[Boolean] of DWORD = (BS_PUSHBUTTON, BS_DEFPUSHBUTTON); begin inherited CreateParams(Params); CreateSubClass(Params, 'BUTTON'); Params.Style := Params.Style or ButtonStyles[FDefault]; end; procedure TCustomCheckBox.CreateParams(var Params: TCreateParams); const Alignments: array[Boolean, TLeftRight] of DWORD = ((BS_LEFTTEXT, 0), (0, BS_LEFTTEXT)); begin inherited CreateParams(Params); CreateSubClass(Params, 'BUTTON'); with Params do begin Style := Style or BS_3STATE or Alignments[UseRightToLeftAlignment, FAlignment]; WindowClass.style := WindowClass.style and not (CS_HREDRAW or CS_VREDRAW); end; end; procedure TRadioButton.CreateParams(var Params: TCreateParams); const Alignments: array[Boolean, TLeftRight] of DWORD = ((BS_LEFTTEXT, 0), (0, BS_LEFTTEXT)); begin inherited CreateParams(Params); CreateSubClass(Params, 'BUTTON'); with Params do Style := Style or BS_RADIOBUTTON or Alignments[UseRightToLeftAlignment, FAlignment]; end; procedure TCustomListBox.CreateParams(var Params: TCreateParams); type PSelects = ^TSelects; TSelects = array[Boolean] of DWORD; const Styles: array[TListBoxStyle] of DWORD = (0, LBS_OWNERDRAWFIXED, LBS_OWNERDRAWVARIABLE, LBS_OWNERDRAWFIXED, LBS_OWNERDRAWFIXED); Sorteds: array[Boolean] of DWORD = (0, LBS_SORT); MultiSelects: array[Boolean] of DWORD = (0, LBS_MULTIPLESEL); ExtendSelects: array[Boolean] of DWORD = (0, LBS_EXTENDEDSEL); IntegralHeights: array[Boolean] of DWORD = (LBS_NOINTEGRALHEIGHT, 0); MultiColumns: array[Boolean] of DWORD = (0, LBS_MULTICOLUMN); TabStops: array[Boolean] of DWORD = (0, LBS_USETABSTOPS); CSHREDRAW: array[Boolean] of DWORD = (CS_HREDRAW, 0); Data: array[Boolean] of DWORD = (LBS_HASSTRINGS, LBS_NODATA); var Selects: PSelects; begin inherited CreateParams(Params); CreateSubClass(Params, 'LISTBOX'); with Params do begin Selects := @MultiSelects; if FExtendedSelect then Selects := @ExtendSelects; Style := Style or (WS_HSCROLL or WS_VSCROLL or Data[Self.Style in [lbVirtual, lbVirtualOwnerDraw]] or LBS_NOTIFY) or Styles[FStyle] or Sorteds[FSorted] or Selects^[FMultiSelect] or IntegralHeights[FIntegralHeight] or MultiColumns[FColumns <> 0] or BorderStyles[FBorderStyle] or TabStops[FTabWidth <> 0]; if NewStyleControls and Ctl3D and (FBorderStyle = bsSingle) then begin Style := Style and not WS_BORDER; ExStyle := ExStyle or WS_EX_CLIENTEDGE; end; WindowClass.style := WindowClass.style and not (CSHREDRAW[UseRightToLeftAlignment] or CS_VREDRAW); end; end; procedure TScrollBar.CreateParams(var Params: TCreateParams); const Kinds: array[TScrollBarKind] of DWORD = (SBS_HORZ, SBS_VERT); begin inherited CreateParams(Params); CreateSubClass(Params, 'SCROLLBAR'); Params.Style := Params.Style or Kinds[FKind]; if FKind = sbVertical then if not UseRightToLeftAlignment then Params.Style := Params.Style or SBS_RIGHTALIGN else Params.Style := Params.Style or SBS_LEFTALIGN; if NotRightToLeft then FRTLFactor := 1 else FRTLFactor := -1; end; procedure TCustomStaticText.CreateParams(var Params: TCreateParams); const Alignments: array[Boolean, TAlignment] of DWORD = ((SS_LEFT, SS_RIGHT, SS_CENTER), (SS_RIGHT, SS_LEFT, SS_CENTER)); Borders: array[TStaticBorderStyle] of DWORD = (0, WS_BORDER, SS_SUNKEN); begin inherited CreateParams(Params); CreateSubClass(Params, 'STATIC'); with Params do begin Style := Style or SS_NOTIFY or Alignments[UseRightToLeftAlignment, FAlignment] or Borders[FBorderStyle]; if not FShowAccelChar then Style := Style or SS_NOPREFIX; WindowClass.style := WindowClass.style and not CS_VREDRAW; end; end;
再看看RichEdit的封装代码：
procedure TCustomRichEdit.CreateParams(var Params: TCreateParams); const RichEditModuleName = 'RICHED32.DLL'; HideScrollBars: array[Boolean] of DWORD = (ES_DISABLENOSCROLL, 0); HideSelections: array[Boolean] of DWORD = (ES_NOHIDESEL, 0); begin if FRichEditModule = 0 then begin FRichEditModule := LoadLibrary(RichEditModuleName); if FRichEditModule <= HINSTANCE_ERROR then FRichEditModule := 0; end; inherited CreateParams(Params); CreateSubClass(Params, 'RICHEDIT'); with Params do begin Style := Style or HideScrollBars[FHideScrollBars] or HideSelections[HideSelection]; WindowClass.style := WindowClass.style and not (CS_HREDRAW or CS_VREDRAW); end; end;
