插入和改写

{ TOvrEdit
--------
An improved TEdit component which reflect keyboard
insert/overwrite mode, Special desiged for Windows
Traditional Chinese Version.
by Wolfgang Chien <wolfgang@ms2.hinet.net>
}
unit OEdit;
interface
{$ifdef Windows}
uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics,
Controls, Forms, Dialogs, StdCtrls;
{$endif}
{$ifdef Win32}
uses
SysUtils, Windows, Messages, Classes, Graphics,
Controls, Forms, Dialogs, StdCtrls;
{$endif}
type
TInsertKeyStates = (iksInsert, iksOverWrite);
TOvrEdit = class(TEdit)
private
FTabOnEnter: boolean;
FInsertKeyState: boolean;
procedure WMChar(var Msg: TWMKey); message WM_Char;
protected
procedure KeyDown(var Key: Word; Shift: TShiftState); override;
procedure KeyPress(var Key: Char); override;
function GetInsertKeyState: TInsertKeyStates;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
property InsertKeyState: TInsertKeyStates read GetInsertKeyState;
published
property TabOnEnter: boolean
read FTabOnEnter write FTabOnEnter default True;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('Samples', [TOvrEdit]);
end;
constructor TOvrEdit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
TabOnEnter := True;
end;
(* -------------------------------------------------- *)
destructor TOvrEdit.Destroy;
begin
inherited Destroy;
end;
(* -------------------------------------------------- *)
procedure TOvrEdit.KeyDown(var Key: Word;
Shift: TShiftState);
begin
if TabOnEnter then
begin
case Key of
vk_Down: { Dn-Arrow Key }
begin
SendMessage(GetParentForm(Self).Handle, wm_NextDlgCtl, 0, 0);
Key := 0;
end;
vk_Up: { Up-Arrow Key }
begin
SendMessage(GetParentForm(Self).Handle, wm_NextDlgCtl, 1, 0);
Key := 0;
end;
end;
end;
if Key <> 0 then inherited KeyDown(Key, Shift);
end;
(* -------------------------------------------------- *)
procedure TOvrEdit.KeyPress(var Key: Char);
begin
if TabOnEnter and (Key = #13) then { Enter Key }
begin
SendMessage(GetParentForm(Self).Handle, wm_NextDlgCtl, 0, 0);
Key := #0;
end;
if Key <> #0 then inherited KeyPress(Key);
end;
(* -------------------------------------------------- *)
function TOvrEdit.GetInsertKeyState: TInsertKeyStates;
begin
if GetKeyState(VK_INSERT) = 0 then
Result := iksInsert
else
Result := iksOverWrite;
end;
(* -------------------------------------------------- *)
procedure TOvrEdit.WMChar(var Msg: TWMKey);
begin
{ if Overwrite state and user select nothing }
if (InsertKeyState = iksOverWrite) and (SelLength = 0)
and (SelStart < GetTextLen) then
begin
{ ASCII Extend code > 127 ==> Chinese word Lead-byte, BIG-5 }
if Msg.CharCode > 127 then
SelLength := 2
else
begin
SelLength := 2;
{ if char on current Caret positon is a Chinese word }
if Ord(SelText[1]) > 127 then
SelLength := 2
else
SelLength := 1;
end;
end;
inherited;
end;
end.