请问不使用第三组件怎样打印 grid的内容，现在希望可以学习继承类的方法去实现这功能

希望可以帮到你：在 uses 中加 printers;pointX:=Trunc(GetDeviceCaps(Printer.Handle,LOGPIXELSX)/2.54);
PointY:=Trunc(GetDeviceCaps(Printer.Handle,LOGPIXELSY)/2.54);
PointScale:=Trunc(GetDeviceCaps(Printer.Handle,LOGPIXELSX)/Screen.PixelsPerInch+0.5);
printer.Orientation:=poLandscape;
printer.Canvas.Font.Name:='宋体';
printer.canvas.Font.Size:=10;
s:='广东省发票系统';
PrintStep:=printer.canvas.TextHeight(s)+16;
x:=PointX*LeftBlank;
y:=PointY*TopBlank;
if ((DataSource1.DataSet).Active=true) and ((DataSource1.DataSet).RecordCount>0)then
begin
printer.BeginDoc;
(DataSource1.DataSet).First;
while not (DataSource1.DataSet).Eof do
begin
for i:=0 to DBGrid1.FieldCount-1 do
begin
if (x+DBGrid1.Columns.Items[i].Width*PointScale)<=(Printer.PageWidth-PointX*RightBlank) then
begin
Printer.Canvas.Rectangle(x,y,x+DBGrid1.Columns.Items[i].Width*PointScale,y+PrintStep);
if y=PointY*TopBlank then
Printer.Canvas.TextOut(x+8,y+8,DBGrid1.Columns[i].Title.Caption)
else
begin
 if i=0 then
 begin
  if pos(DBGrid1.Fields[0].asString,'.')=0 then
     Printer.Canvas.TextOut(x+8,y+8,DBGrid1.Fields[0].asString+'.00');
  end
  else
Printer.Canvas.TextOut(x+8,y+8,DBGrid1.Fields[i].asString);
end;
       end; //计算下一列的横坐标 
x:=x+DBGrid1.Columns.Items[i].Width*PointScale;
end;
if not (y=PointY*TopBlank) then
     (DataSource1.DataSet).next;x:=PointX*LeftBlank;
y:=y+PrintStep;
end;
printer.EndDoc;
(DataSource1.DataSet).First;
Application.MessageBox('打印完成','打印',32);
end;
end;