gnuplot-beta

bug in wx terminal for linewidth 0

[Petr M. <mi...@ph...>]

It seems that WXT is incorrectly setting the linewidth 0 to be really a zero 
thickness, instead of the smallest linewidth achievable (as all other 
terminals are doing).

Compare:

plot sin(x) w l lw 0, cos(x) w l lw 1
set term wxt; replot
set term png size 900,700; set out 'a.png'; replot
set term post color; set out 'a.ps'; replot
set term fig color; set out 'a.fig'; replot

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PM

Re: bug in wx terminal for linewidth 0

[<tim...@lp...>]

Petr Mikulik a écrit :
> It seems that WXT is incorrectly setting the linewidth 0 to be really a zero 
> thickness, instead of the smallest linewidth achievable (as all other 
> terminals are doing).
>
> Compare:
>
> plot sin(x) w l lw 0, cos(x) w l lw 1
> set term wxt; replot
> set term png size 900,700; set out 'a.png'; replot
> set term post color; set out 'a.ps'; replot
> set term fig color; set out 'a.fig'; replot
>
> ---
> PM
>   

Hi Petr,

I don't know what's the proper answer to this, but from "help linestyle" 
I can read:
"The line width and point size are multipliers for the default width and 
size"
And the smallest achievable linewidth for cairo-based terminals is 
definetely zero. It is a consequence of antialiasing. For example, try:

plot x-2 lw 3 lt 1, x-1 lw 2 lt 1, x lw 1 lt 1, x+1 lw .8 lt 1, x+2 lw 
.5 lt 1, x+3 lw .3 lt 1, x+4 lw .1 lt 1, x+5 lw .03 lt 1

You will probably see that even at lw 0.03 the line is visible and looks 
indeed very thin.
Do you think we should decided of a lower bound on the linewidth for 
cairo-based terminals ?

Best regards,

Timothée

Re: bug in wx terminal for linewidth 0

[Petr M. <mi...@ph...>]

> > It seems that WXT is incorrectly setting the linewidth 0 to be really a zero 
> > thickness, instead of the smallest linewidth achievable (as all other 
> > terminals are doing).
> >
> > Compare:
> >
> > plot sin(x) w l lw 0, cos(x) w l lw 1
> > set term wxt; replot
> > set term png size 900,700; set out 'a.png'; replot
> > set term post color; set out 'a.ps'; replot
> > set term fig color; set out 'a.fig'; replot
> 
> I don't know what's the proper answer to this, but from "help linestyle" 
> I can read:
> "The line width and point size are multipliers for the default width and 
> size"
> And the smallest achievable linewidth for cairo-based terminals is 
> definetely zero. It is a consequence of antialiasing. For example, try:
> 
> plot x-2 lw 3 lt 1, x-1 lw 2 lt 1, x lw 1 lt 1, x+1 lw .8 lt 1, x+2 lw 
> .5 lt 1, x+3 lw .3 lt 1, x+4 lw .1 lt 1, x+5 lw .03 lt 1
> 
> You will probably see that even at lw 0.03 the line is visible and looks 
> indeed very thin.

All these lines below lw 1 have thickness 1 pixel, but they are lighter 
(I had a look by "kmag"). 

> Do you think we should decided of a lower bound on the linewidth for 
> cairo-based terminals ?

I think the limit should be "lw 1" -- thus, all linewidths < 1 should be 
equivalent to linewidth 1. I seems that all terminals work this way.

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PM

Re: bug in wx terminal for linewidth 0

[Ethan A M. <merritt@u.washington.edu>]

On Sunday 09 December 2007 06:18, Petr Mikulik wrote:
> I think the limit should be "lw 1" -- thus, all linewidths < 1 should be 
> equivalent to linewidth 1. I seems that all terminals work this way.

This is not true for PostScript or PDF.

PostScript (the language, not the terminal driver) has the rule
"0 linewidth means as thin as the device supports".
So on a 1200dpi printer, linewidth 0 produces  about the same as
linewidth 0.06  

-- 
Ethan A Merritt

Re: bug in wx terminal for linewidth 0

[Petr M. <mi...@ph...>]

> > I think the limit should be "lw 1" -- thus, all linewidths < 1 should be 
> > equivalent to linewidth 1. I seems that all terminals work this way.
> 
> This is not true for PostScript or PDF.
> 
> PostScript (the language, not the terminal driver) has the rule
> "0 linewidth means as thin as the device supports".
> So on a 1200dpi printer, linewidth 0 produces  about the same as
> linewidth 0.06  

Yes; however, if you look at the same file on screen by ghostscript, you see 
all these lines very well.

wxt is a screen terminal, so the limit is one pixel.

---
PM