I’m trying to learn how to use TTextLayout object to add some special characters to my graphic drawings.
Unfortunately this object seems having some special behaviours that seem not documented in Delphi help docs and on Embarcadero online docs.
I have derived the following code from the Delphi code examples adding some features that I need to use.
Teese features are the usage of TextWidth and TextHeight to obtain the width and height of the characters to be drawn.
For convenience I have replaced the font I’m using with the Arial font.
I have added some buttons to enlarge/reduce the size of the character, and some other buttons to choose different characters. Well, when the character changes, and when the size changes, nothing seems to change in width and height of the TTextLayout object. The values of width and height of the object seem remain the same.
I have tried whatever came to my mind, putting before or after each single statement, but nothing. The Width and Height of the TTextLayout seem remain the same.
What I’m doing wrong? What is it that I’m not understanding correctly?
Thankyou for your kind help, as usual.

unit MainGraphicText;
interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,
  FMX.StdCtrls, FMX.Controls.Presentation, FMX.Objects,FMX.TextLayout, FMX.Edit;

type
  TMainFormGraphicText = class(TForm)
    Image1: TImage;
    Width: TEdit;
    Height: TEdit;
    DimLess: TButton;
    Label1: TLabel;
    DimMore: TButton;
    Label2: TLabel;
    ShowDim: TEdit;
    ShowChar: TEdit;
    CharLess: TButton;
    CharMore: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Image1Paint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);
    procedure DimLessClick(Sender: TObject);
    procedure DimMoreClick(Sender: TObject);
    procedure CharLessClick(Sender: TObject);
    procedure CharMoreClick(Sender: TObject);
  private
    { Private declarations }
  public
     WhichChar : Integer;
     Dimension : Single;
     MyRect : TRectF;
  end;

var
  MainFormGraphicText: TMainFormGraphicText;

implementation

{$R *.fmx}


procedure TMainFormGraphicText.CharMoreClick(Sender: TObject);
begin
   WhichChar := WhichChar + 1;
   if WhichChar > 80 then
      WhichChar := 80;
   ShowChar.Text := WhichChar.ToString;
   Image1.Repaint;
end;

procedure TMainFormGraphicText.CharLessClick(Sender: TObject);
begin
   WhichChar := WhichChar - 1;
   if WhichChar < 1 then
      WhichChar := 1;
   ShowChar.Text := WhichChar.ToString;
   Image1.Repaint;
end;

procedure TMainFormGraphicText.DimLessClick(Sender: TObject);
begin
   Dimension := Dimension - 1;
   if Dimension < 9 then
      Dimension := 9;
   ShowDim.Text := Dimension.ToString;
   Image1.Repaint;
end;

procedure TMainFormGraphicText.DimMoreClick(Sender: TObject);
begin
   Dimension := Dimension + 1;
   if Dimension > 72 then
      Dimension := 72;
   ShowDim.Text := Dimension.ToString;
   Image1.Repaint;
end;

procedure TMainFormGraphicText.FormCreate(Sender: TObject);
begin
   WhichChar := 40;
   Dimension := 48;
   MyRect := TRect.Create(TPoint.Create(0, 0),Trunc(Image1.Width),Trunc(Image1.Height));
   Canvas.BeginScene;
   Canvas.Stroke.Kind := TBrushKind.Solid;
   Canvas.Stroke.Color := TAlphaColorRec.Black;
   Canvas.Stroke.Thickness := 1.0;
   Canvas.DrawRect(MyRect,1);
   Canvas.EndScene;
end;

procedure TMainFormGraphicText.Image1Paint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);
Const Acapo = '#13#10';
var
  WPosition: Integer;
  W,H : Single;
  MyLayout: TTextLayout;
begin

  Canvas.BeginScene;
  Canvas.Stroke.Kind := TBrushKind.Solid;
  Canvas.Stroke.Color := TAlphaColorRec.Black;
  Canvas.Stroke.Thickness := 1.0;
  Canvas.DrawRect(MyRect,1);
  Canvas.EndScene;
  MyLayout := TTextLayoutManager.DefaultTextLayout.Create;
  MyLayout.BeginUpdate;
  MyLayout.TopLeft := TPointF.Create(0, 0);
  MyLayout.Font.Family := 'Arial'; // 'Delfos2';
  MyLayout.Font.Size := Dimension;
  MyLayout.Font.Style := [];
  MyLayout.Trimming := TTextTrimming.Character;
  MyLayout.Text := chr(63 + WhichChar); // Copy(Aspetti_Delfos2,WhichChar,1);
  MyLayout.Color := TAlphaColorRec.Brown;
  ShowDim.Text := MyLayout.Font.Size.ToString;
  ShowChar.Text := WhichChar.ToString;
  WPosition := MyLayout.PositionAtPoint(TPointF.Create(0, 0));
  Width.Text := MyLayout.TextWidth.ToString;
  Height.Text := MyLayout.TextHeight.ToString;
  MyLayout.EndUpdate;
  MyLayout.RenderLayout(Canvas);
  MyLayout.Free;
end;
end.