Générer et afficher un code‑barres

unit UnitBarcodeForm;

interface

uses
  System.SysUtils, System.Classes, Vcl.Forms, Vcl.Controls, Vcl.ExtCtrls,
  Vcl.StdCtrls, Vcl.Graphics, System.Net.HttpClient, System.Net.URLClient,
  System.NetEncoding, System.Threading, PNGImage, Vcl.Dialogs;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
  private
    procedure ShowError(const Msg: string);
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  DEFAULT_BARCODE_TYPE = 'code128'; // changer ici si besoin (ex: 'qr', 'ean13', 'code39', ...)

procedure TForm1.ShowError(const Msg: string);
begin
  TThread.Queue(nil,
    procedure
    begin
      ShowMessage(Msg);
      Button1.Enabled := True;
    end);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  BarcodeType, DataText, URL: string;
begin
  BarcodeType := DEFAULT_BARCODE_TYPE;
  DataText := Trim(Edit1.Text);
  if DataText = '' then
  begin
    ShowMessage('Saisissez le texte à encoder dans le TEdit.');
    Exit;
  end;

  URL := Format('https://barcodeapi.org/api/%s/%s', [BarcodeType, TNetEncoding.URL.Encode(DataText)]);

  Button1.Enabled := False;
  TTask.Run(
    procedure
    var
      Http: THTTPClient;
      MS: TMemoryStream;
      Resp: IHTTPResponse;
      Png: TPngImage;
    begin
      Http := THTTPClient.Create;
      MS := TMemoryStream.Create;
      try
        Http.UserAgent := 'DelphiBarcodeClient/1.0';
        try
          Resp := Http.Get(URL, MS);
        except
          on E: Exception do
          begin
            ShowError('Erreur réseau: ' + E.Message);
            Exit;
          end;
        end;

        if Resp.StatusCode <> 200 then
        begin
          ShowError(Format('Erreur HTTP %d: %s', [Resp.StatusCode, Resp.StatusText]));
          Exit;
        end;

        MS.Position := 0;
        Png := TPngImage.Create;
        try
          Png.LoadFromStream(MS);
          TThread.Queue(nil,
            procedure
            begin
              try
                Image1.Picture.Assign(Png);
              finally
                Png.Free;
                Button1.Enabled := True;
              end;
            end);
        except
          Png.Free;
          ShowError('Le flux reçu n''est pas une image PNG valide.');
          Exit;
        end;
      finally
        MS.Free;
        Http.Free;
      end;
    end);
end;

end.