why Text clip in TEdit doesn't get changed when it is created first time [closed]

Question

Hi I'm trying to build an TEdit control with TButton to have Buttoned Edit but the problem is that the text clip gets under the Button and some latter doesn't appear because the button is over it. how to fix that? please note that when I call UpdateEditMargins (which is the procedure to adjust the text clip)

Here is my code:

unit YazButtonedEdit;

interface

uses
  SysUtils, Classes, Controls, StdCtrls, Buttons, Messages, Windows, Forms;

type
  TYazButtonedEdit = class(TCustomEdit)
  private
    FEditButton: TBitBtn;
    FButtonWidth: Integer;
    FButtonVisible: Boolean;
    procedure WMSize(var Message: TMessage); message WM_SIZE;
    procedure SetButtonVisible(const Value: Boolean);
    procedure GetEditButtonClick(const Value: TNotifyEvent);
    function SetEditButtonClick: TNotifyEvent;
    procedure SetButtonWidth(const Value: Integer);
  protected
    procedure RefreshButton;
    procedure CreateParams(var Params: TCreateParams); override;
    procedure WndProc(var Message: TMessage); override;
  public
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure UpdateEditMargins;
  published
    property ButtonWidth: Integer read FButtonWidth write SetButtonWidth;
    property ButtonVisible: Boolean read FButtonVisible write SetButtonVisible;
    property OnEditButtonClick: TNotifyEvent read SetEditButtonClick write GetEditButtonClick;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('KH-Controls', [TYazButtonedEdit]);
end;

{ TYazButtonedEdit }

constructor TYazButtonedEdit.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  ControlStyle := ControlStyle - [csSetCaption];

  FEditButton := TBitBtn.Create(self);
  with FEditButton do begin
     Parent := self;
     TabStop := false;
     Visible := true;
     OnClick := OnEditButtonClick;
  end;
end;

procedure TYazButtonedEdit.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  Params.Style := Params.Style or WS_CLIPCHILDREN;
end;

destructor TYazButtonedEdit.Destroy;
begin
  FEditButton.Free;
  inherited;
end;

procedure TYazButtonedEdit.GetEditButtonClick(const Value: TNotifyEvent);
begin
  FEditButton.OnClick := Value;
end;

procedure TYazButtonedEdit.RefreshButton;
begin
  FEditButton.Width := ButtonWidth;
  FEditButton.Height := Height - 4;
  FEditButton.Visible := ButtonVisible;
  UpdateEditMargins;
end;

procedure TYazButtonedEdit.SetButtonVisible(const Value: Boolean);
begin
  if FButtonVisible <> Value then
  begin
    FButtonVisible := Value;
    RefreshButton;
  end;
end;

procedure TYazButtonedEdit.SetButtonWidth(const Value: Integer);
begin
  if FButtonWidth <> Value then
  begin
    FButtonWidth := Value;
    RefreshButton;
  end;
end;

function TYazButtonedEdit.SetEditButtonClick: TNotifyEvent;
begin
  Result := FEditButton.OnClick;
end;

procedure TYazButtonedEdit.WMSize(var Message: TMessage);
begin
  RefreshButton;
end;

procedure TYazButtonedEdit.WndProc(var Message: TMessage);
var
  LLeft, LTop: Integer;
begin
  case Message.Msg of
    CN_CTLCOLORSTATIC,
    CN_CTLCOLOREDIT:
        if FEditButton.Visible then
        begin
          LLeft := FEditButton.Left;
          LTop := FEditButton.Top;
          ExcludeClipRect(Message.WParam, LLeft + 1, LTop + 1,
            FEditButton.Width + FEditButton.Left - 1, FEditButton.Height - 1);
        end;
  end;
  inherited;
end;

procedure TYazButtonedEdit.UpdateEditMargins;
var
  LMargin, RMargin: Integer;
begin
  if HandleAllocated then
  begin
    LMargin := 0;
    RMargin := 0;
    if FEditButton.Visible then
        LMargin := FEditButton.Width + 2;
    SendMessage(Handle, EM_SETMARGINS, EC_LEFTMARGIN or EC_RIGHTMARGIN, MakeLong(LMargin, RMargin));
    Invalidate;
  end;
end;

procedure TYazButtonedEdit.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited Notification(AComponent, Operation);
  if Operation = opRemove then
  begin
    if AComponent = FEditButton then
    begin
      RefreshButton;
    end;
  end;
end;

end.

Answer 1

Call it after the edit window is created, ideally in CreateWnd method. So, add the following:

type
  TYazButtonedEdit = class(TCustomEdit)
  ...
  protected
    procedure CreateWnd; override;
  ...
  end;

implementation

procedure TYazButtonedEdit.CreateWnd;
begin
  inherited;
  UpdateEditMargins;
end;