[tex-k] Question about MetaFont online display

[Igor Liferenko]

Hi all,

I would like to report a possible bug in MetaFont.

I have setup a test environment to reproduce it:

git clone git://github.com/igor-liferenko/mf && cd mf
make x
./mf test

In the output you will see redundant calls to blankrectangle and updatescreen:


This is METAFONT, Version 2.7182818 (TeX Live 2017) (preloaded base=mf)
(test.mf
initscreen called

blankrectangle called

updatescreen called

blankrectangle called

updatescreen called
)
*


Except these duplicate calls being useless, they may also cause undesirable
small initial blinking effect in an online display driver.

Anyway, these duplicate calls are strange and cause a question for
what they are needed.

Does anybody have an opinion on this?

Regards,
Igor

[Igor Liferenko]

Hi all,

This is a workaround that I have to use for now:


+int this_updatescreen_is_tied_to_initscreen = 0;
int
mf_x11_initscreen (void)
{
+ this_updatescreen_is_tied_to_initscreen = 1;

void
mf_x11_updatescreen (void)
{
+ if (this_updatescreen_is_tied_to_initscreen) {
+ this_updatescreen_is_tied_to_initscreen = 0;
+ return;
+ }



Igor