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Article: 

Advanced editing - TadpEdit component

http://delphi.about.com/library/weekly/aa120603a.htm

Full source code of a TadpEdit Delphi component, an extension
to the standard TEdit control with properties like: ColorOnEnter 
(changes the background color of the control when it receives the 
input focus), Alignment (determines how the text in the edit component 
is aligned), and TabOnEnter (allows the edit control to react on 
the Enter key press as if the Tab key was pressed - sending the 
focus to the next control in the tab order).
}

Download zipped source

adpEdit.pas

unit adpEdit; interface uses SysUtils, Classes, Controls, StdCtrls, Graphics, Windows, Messages; type TadpEdit = class(TEdit) private FOldBackColor : TColor; FColorOnEnter : TColor; FAlignment: TAlignment; FTabOnEnter: boolean; procedure SetAlignment(const Value: TAlignment); property OldBackColor : TColor read FOldBackColor write FOldBackColor; protected procedure DoEnter; override; procedure DoExit; override; procedure KeyPress(var Key: Char); override; procedure CreateParams(var Params: TCreateParams); override; public constructor Create(AOwner:TComponent); override; published property Alignment : TAlignment read FAlignment write SetAlignment; property ColorOnEnter : TColor read FColorOnEnter write FColorOnEnter; property TabOnEnter : boolean read FTabOnEnter write FTabOnEnter; end; procedure Register; implementation procedure Register; begin RegisterComponents('delphi.about.com', [TadpEdit]); end; { TadpEdit } procedure TadpEdit.CreateParams(var Params: TCreateParams); const Alignments: array[TAlignment] of DWORD = (ES_LEFT, ES_RIGHT, ES_CENTER); begin inherited CreateParams(Params); with Params do Style := Style or Alignments[FAlignment]; end; (*CreateParams*) constructor TadpEdit.Create(AOwner: TComponent); begin inherited; FColorOnEnter := Color; Alignment := taLeftJustify; end; (*Create*) procedure TadpEdit.DoEnter; begin OldBackColor := Color; Color := ColorOnEnter; inherited; end; (*DoEnter*) procedure TadpEdit.DoExit; begin Color := OldBackColor; inherited; end; (*DoExit*) procedure TadpEdit.SetAlignment(const Value: TAlignment); begin if FAlignment <> Value then begin FAlignment := Value; RecreateWnd; end; end; (*SetAlignment*) procedure TadpEdit.KeyPress(var Key: Char); begin inherited KeyPress(Key); if TabOnEnter AND (Owner is TWinControl) then begin if Key = Char(VK_RETURN) then begin if HiWord(GetKeyState(VK_SHIFT)) <> 0 then PostMessage((Owner as TWinControl).Handle, WM_NEXTDLGCTL, 1, 0) else PostMessage((Owner as TWinControl).Handle, WM_NEXTDLGCTL, 0, 0); Key := #0; end; end; end; (*KeyPress*) end. (*adpEdit.pas*) { ******************************************** Zarko Gajic About.com Guide to Delphi Programming http://delphi.about.com email: delphi@aboutguide.com free newsletter: http://delphi.about.com/library/blnewsletter.htm forum: http://forums.about.com/ab-delphi/start/ ******************************************** }

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