[cairo] After 'set_line_width', subsequent stroking is slow [ Background image]

[Olivier Jolet]

> > On 2/20/07, Olivier Jolet <olivier.jolet at skynet.be> wrote:
> > > Also, I have another problem of performance, if I use the
> > > 'cairo_set_line_width' primitive, it is very much slower. I don't
> > > understand why there is a such difference?
> >
> > Neither do I. I don't think I'm understanding you. Do you mean that
> > when you call set_line_width, all subsequent stroking is slower than
> > when you don't? Obviously the call to cairo_set_line_width itself is
> > really fast, so I don't think you're referring to that.
> 
> Yes, I think it's exactly that. When I do not call set_line_width, all
> subsequent stroking is faster.
> 
> > > It's a little complicated to provide the code + data because it is
> based
> > > on a greater real time application.
> >
> > Understandable. You could try capturing the data from a given run,
> > which would allow one to later replay the drawing without the need
for
> > the full application. You already have all your drawing code
> > centralized in that small interpreter, so adding some logging
> > capabilities shouldn't be too painful. Come to think of it, you
could
> > probably easily write out all that drawing data you already have in
> > that dlbuf variable I saw in your code.
> >
> > Dan
> 
> I will try.
> 
> Oli

WITHOUT SET_WIDTH				WITH SET_WIDTH

=================         		==============            
Primitives : 5340         		Primitives : 5340         
TIME to draw: 68.813 msec 		TIME to draw: 397.58 msec 
Primitives : 5346         		Primitives : 5346         
TIME to draw: 63.405 msec 		TIME to draw: 297.517 msec
Primitives : 5345         		Primitives : 5345         
TIME to draw: 62.746 msec 		TIME to draw: 287.675 msec
Primitives : 5322         		Primitives : 5321         
TIME to draw: 64.246 msec 		TIME to draw: 291.121 msec
Primitives : 5209         		Primitives : 5210         
TIME to draw: 63.504 msec 		TIME to draw: 246.034 msec
Primitives : 5171         		Primitives : 5165         
TIME to draw: 63.391 msec 		TIME to draw: 244.956 msec