Re: Argh: Why are arrows clipped to the graph?

[Harald H. <h.h...@tu...>]

On Wed, 9 Nov 2005, Ethan Merritt wrote:

> On Wednesday 09 November 2005 03:04 pm, Daniel J Sebald wrote:
> > I don't know if I agree on that one.  Are you saying that one
> > can't have a fraction of an arrow at the edge of the canvas
> > (i.e., say the tip extends just past the canvas limit, but is
> > not visible)?  That has to be allowed, otherwise one can't use
> > the many features of PostScript.
>
> If you try this with the pdf terminal, it will crash.
> Therefore if you want a program that doesn't crash, you have
> to clip off the protruding piece of the arrow before sending
> it to the driver.  Yes, I know PostScript won't crash if you
> draw outside the boundaries.  But don't you think we should
> aim for code that works (or at least doesn't crash) on all
> the other terminal types as well?

Why do so many routines have clipping? In my opinion we have about four
things that have to be clipped, in most terminals:

points
lines
filled polygons
text

Since arrows are produced by lines and filled polygons in most terminals,
clipping would be done automatically by the routines producing the lines
and the polygons. As a positive side effect, only the part of the arrow
head would be cut off that is outside the canvas.

But that does not solve the current problem that things are cut off which
are inside the canvas.

Harald

-- 
Harald Harders
h.h...@tu...
http://www.harald-harders.de