2008/02/14 | Tprinter of delphi
类别(语言类学习笔记) | 评论(0) | 阅读(150) | 发表于 20:39
Like   TCanvas,   the   TPrinter   class   does   not   belong   to   BaseCLX   because   there   are   two   separate   versions,   one   for   VCL   applications   (in   the   Printers   unit)   and   one   for   CLX   applications   (in   the   QPrinters   unit).   The   VCL   TPrinter   object   encapsulates   details   of   Windows   printers.   The   CLX   TPrinter   object   is   a   paint   device   that   paints   on   a   printer.   It   generates   postscript   and   sends   that   to   lpr,   lp,   or   another   print   command.   Both   versions   of   TPrinter,   however,   are   extremely   similar.  
   
  To   get   a   list   of   installed   and   available   printers,   use   the   Printers   property.   Both   printer   objects   use   a   TCanvas   (which   is   identical   to   the   form's   TCanvas)   which   means   that   anything   that   can   be   drawn   on   a   form   can   be   printed   as   well.   To   print   an   image,   call   the   BeginDoc   method   followed   by   whatever   canvas   graphics   you   want   to   print   (including   text   through   the   TextOut   method)   and   send   the   job   to   the   printer   by   calling   the   EndDoc   method.    
   
  This   example   uses   a   button   and   a   memo   on   a   form.   When   the   user   clicks   the   button,   the   content   of   the   memo   is   printed   with   a   200-pixel   border   around   the   page.    
   
  To   run   this   example   successfully,   add   Printers   to   your   uses   clause.  
   
  procedure   TForm1.Button1Click(Sender:   TObject);  
  var  
      r:   TRect;  
      i:   Integer;  
  begin  
      with   Printer   do  
          begin  
              r   :=   Rect(200,200,(Pagewidth   -   200),(PageHeight   -   200));  
              BeginDoc;  
              Canvas.Brush.Style   :=   bsClear;  
              for   i   :=   0   to   Memo1.Lines.Count   do  
                Canvas.TextOut(200,200   +   (i   *  
                                        Canvas.TextHeight(Memo1.Lines.Strings[i])),  
                                        Memo1.Lines.Strings[i]);  
   
              Canvas.Brush.Color   :=   clBlack;  
              Canvas.FrameRect(r);  
              EndDoc;  
          end;  
  end;  
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