procedure DrawLine(CertainCanvas: TCanvas; fxy, sxy: TPoint);
//画直线
begin
if not SetCanvas(CertainCanvas) then Exit;
try
with CertainCanvas do
begin
MoveTo(fxy.X, fxy.Y);
LineTo(sxy.X, sxy.Y);
end;
finally
RevertCanvas(CertainCanvas);
end;
end;
拿个例子其它自己看看资料.