Programa para imprimir archivo de texto en impresora usb

type
  TPrinterCaps = record
    ppx: integer;
    ppy: integer;
    pox: integer;
    poy: integer;
  end;
 
  TPrinterContext = record
    Caps: TPrinterCaps;
    Cursor: TPoint;
    Inter: Double;
  end;
 
function CreatePrinterContext: TPrinterContext;
begin
  FillChar(Result,Sizeof(Result),0);
  with Result.Caps do
  begin
    ppx:= GetDeviceCaps(Printer.Handle, LOGPIXELSX);
    ppy:= GetDeviceCaps(Printer.Handle, LOGPIXELSY);
    pox:= GetDeviceCaps(Printer.Handle, PHYSICALOFFSETX);
    poy:= GetDeviceCaps(Printer.Handle, PHYSICALOFFSETY);
  end;
  Result.Inter:= 1.5;
end;
 
function ToPixelsX(X: Double; Context: TPrinterContext): Integer;
begin
  with Context.Caps do
    Result:= Round((X / 25.4) * ppx) - pox;
end;
 
function ToPixelsY(Y: Double; Context: TPrinterContext): Integer;
begin
  with Context.Caps do
    Result:= Round((Y / 25.4) * ppy) - poy;
end;
 
procedure SetPrinterCursor(X, Y: Double; var Context: TPrinterContext);
begin
  with Context do
  begin
    if X > 0 then Cursor.X:= ToPixelsX(X,Context);
    if Y > 0 then Cursor.Y:= ToPixelsY(Y,Context);
  end;
end;
 
procedure IncPrinterCursor(var Context: TPrinterContext);
begin
  with Context, Context.Caps do
  begin
    Cursor.Y:= Cursor.Y + Round(Inter*(Printer.Canvas.Font.Size * ppy) / 72);
  end;
end;
 
procedure DecPrinterCursor(var Context: TPrinterContext);
begin
  with Context, Context.Caps do
  begin
    Cursor.Y:= Cursor.Y - Round(Inter*(Printer.Canvas.Font.Size * ppy) / 72);
  end;
end;
 
procedure PrinterWrite(Width: Double; alRight: Boolean; Str: string;
  Context: TPrinterContext);
var
  Rectangle: TRect;
begin
  with Context, Context.Caps do
  begin
    Rectangle.Left:= Cursor.X;
    Rectangle.Top:= Cursor.Y;
    Rectangle.Right:= Cursor.X + Round((Width / 25.4) * ppx);
    if alRight then Cursor.X:= Rectangle.Right - Printer.Canvas.TextWidth(Str);
    Rectangle.Bottom:=
      Cursor.Y + Round(Inter*(Printer.Canvas.Font.Size * ppy) / 72);
    Printer.Canvas.TextRect(Rectangle,Cursor.X,Cursor.Y,Str);
  end;
end;
 
procedure PrinterTextOut(X, Y: Double; Str: string; Context: TPrinterContext);
begin
  Printer.Canvas.Textout(ToPixelsX(X,Context),ToPixelsY(Y,Context),Str);
end;
 
procedure PrinterCenterText(X, Y: Double; Str: string;
  Context: TPrinterContext);
begin
  Printer.Canvas.Textout(
    ToPixelsX(X,Context) - (Printer.Canvas.TextWidth(Str) div 2),
    ToPixelsY(Y,Context) - (Printer.Canvas.TextHeight(Str) div 2),
    Str);
end;
 
procedure PrinterMoveTo(X, Y: Double; Context: TPrinterContext);
begin
  Printer.Canvas.MoveTo(ToPixelsX(X,Context),ToPixelsY(Y,Context));
end;
 
procedure PrinterLineTo(X, Y: Double; Context: TPrinterContext);
begin
  Printer.Canvas.LineTo(ToPixelsX(X,Context),ToPixelsY(Y,Context));
end;
 
procedure PrinterLine(X1,Y1,X2,Y2: Double; Context: TPrinterContext);
begin
  PrinterMoveTo(X1,Y1,Context);
  PrinterLineTo(X2,Y2,Context);
end;
 
 
// Y uso las funciones anteriores de esta manera
var
  i: Integer;
  Context: TPrinterContext;
begin
  with TPrinterSetupDialog.Create(nil) do
  try
    if Execute then
    with Printer do
    begin
      Printer.Orientation := poPortrait;
      Printer.BeginDoc;
      try
        Context:= CreatePrinterContext;
        Canvas.Font.Name:= 'Arial';
        Canvas.Font.Color:= clBlack;
        Canvas.Font.Size:= 10;
        SetPrinterCursor(20,20,Context);
        for i:= 1 to 20 do
        begin
          PrinterWrite(100,FALSE,'Linea ' + IntToStr(i),Context);
          incPrinterCursor(Context);
        end;
        Printer.EndDoc;
      except
        Printer.Abort;
      end;
    end;
  finally
    Free;
  end;
end;