How do I print the selected rows of a TStringGrid?

Here is a component that I wrote to print out the selected lines (to the printer) of a TStringGrid, it’s called TPrintGrid.
I hope enjoy it, if you have any questions, comments, suggestions - please don't hesitate to ask me.  

-Bradley Baumann
www.scrapcode.com
bradley@bestweb.net / _@scrapcode.com


unit PrintGrid;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Grids, Printers;

type
    TPrintGrid = class(TStringGrid)
    private
           FPrintAborted:boolean;
    protected
    public
    procedure PrintGrid;
    published
  end;

procedure Register;

implementation

procedure TPrintGrid.PrintGrid;
var
   margins: trect;
   spacing: integer;
   cols: tlist;

   procedure setcolumnwidth;
   var
      i, k, w: integer;
   begin
        Printer.Canvas.Font.Style := [ fsBold ];
        for i := 0 to pred( ColCount ) do
            Cols.Add(Pointer(Printer.Canvas.TextWidth(cells[i,0])));
            printer.canvas.font.style := [];
            for i := 1 to pred(rowcount ) do
                for k := 0 to pred(colcount ) do
                begin
                     w:= printer.canvas.textwidth( cells[ k, i ] );
                     if w > integer( cols[ k ] ) then
                        cols[ k ] := pointer( w );
                end;
                w := 2 * printer.canvas.font.pixelsperinch div 3;
                margins :=rect( w, w, printer.pagewidth-w, printer.pageheight - w );
                spacing := printer.canvas.font.pixelsperinch div 10;
                w := 0;
                for i := 0 to pred(cols.count) do
                    w := w + integer( cols[ i ] ) + spacing;
                    w := w - spacing;
                    if w > (margins.right-margins.left ) then
                    begin
                         w := w - (margins.right-margins.left );
                         cols[ cols.count-2 ] :=pointer( integer( cols[ cols.count-2 ] ) - w );
                    end; { if }
                    w:= 0;
                    for i := 0 to pred(cols.count) do
                        w := w + integer( cols[ i ] ) + spacing;
                        margins.right := w - spacing + margins.left;
   end; { setcolumnwidth }

   procedure doprint;
   var
      i: integer;
      y: integer;

      procedure doline(lineno: integer);
      var
         x, n: integer;
         r: trect;
         th: integer;
      begin
           if length(cells[1,lineno]) = 0 then exit;
              x:= margins.left;
              with printer.canvas do
              begin
                   th := textheight( 'Äy' );
                   for n := 0 to pred( cols.count ) do
                   begin
                        r := rect( 0, 0, integer(cols[ n ]), th);
                        offsetrect( r, x, y );
                        textrect( r, x, y, cells[ n, lineno ] );
                        x := r.right + spacing;
                   end; { for }
              end; { with }
              y := y + th;
      end; { doline }

      procedure doheader;
      begin
           y := margins.top;
           with printer.canvas do
           begin
                font.style := [ fsbold ];
                doline( 0 );
                pen.width := font.pixelsperinch div 72;
                pen.color := clblack;
                moveto( margins.left, y );
                lineto( margins.right, y );
                inc( y, 2 * pen.width );
                font.style := [ ];
           end; { with }
      end; { doheader }

      begin
           y:= 0;
           for i := 1 to pred( rowcount ) do
           begin
                application.processmessages;
                if fprintaborted then
                   exit;
                   if y = 0 then
                      doheader;
                      doline( i );
                      if y >= margins.bottom then
                      begin
                           printer.newpage;
                           y:= 0;
                      end; { if }
           end; { for }
      end; { doprint }

      begin
           fprintaborted := false;
           try
              show;
              application.processmessages;
              if printer.printing then
                 {$ifdef win32}
                 printer.abort;
                 {$else}
                 abortdoc( printer.canvas.handle );
                 {$endif}
                 printer.begindoc;
                 cols:= nil;
                 try
                    cols:= tlist.create;
                    {$ifndef win32}
                    printer.canvas.font.pixelsperinch :=
                    getdevicecaps( printer.handle, logpixelsy );
                    {$endif}
                    printer.canvas.font.assign( font );
                    printer.canvas.font.color :=clblack;
                    printer.canvas.pen.color := clblack;
                    setcolumnwidth;
                    application.processmessages;
                    doprint;
                    finally
                           cols.free;
                           if fprintaborted then
                              {$ifdef win32}
                              printer.abort
                              {$else}
                              abortdoc( printer.canvas.handle )
                              {$endif}
                           else
                               printer.enddoc;
      end;
      finally
      begin
      end;
   end;
end; { with }


procedure Register;
begin
  RegisterComponents('PrintGrid', [TPrintGrid]);
end;

end.