xdvipdfmx-20200116 : additional q/Q bracket around BT...ET

[Shunsaku Hirata]

Dear Zdenek,

> > Adding an extra "Q..q" (I assume it is not a typo) does not help. (rather it
> > makes generated PDFs corrupt)
> > Let me explain the original problem: My version of fake-bold patch adds a
> > q-Q block around the text section BT-ET, but as this q-Q block recovers the
> > graphics state saved by "q" at the execution of "Q" operator, clipping path
> > added in the BT-ET section is discarded. This is why my patch broke the
> > ocgx2 package.
>
> It should work. You start by Q which pops out the state pushed by q.
> You know that after your code Q will be added, hence your code must
> end with q so that the added Q can pop anything. It is necessary to
> pair correctly q a Q in order not to corrupt the graphic stack.

Maybe you are talking about the trick to cancel out the effect of q-Q bracket
which is automatically inserted for "pdf:put" command?

I guess the change I made for fixing the fake-bold bug is misunderstood.

Let me explain the problem reported by Alexander and the change I made
for fixing the fake-bold bug which is the cause of the problem.
Note that the behavior of "pdf:code" has not been changed at all.

Input:
  \special{pdf:code q 7 Tr}
 TEXT
  \special{pdf:code -88888 -88888 99999 99999 re f Q}

The old behavior (before the fake-bold bug fix) is to convert them to
    q 7 Tr
    BT --PDF code for drawing "TEXT"-- ET
   -88888 -88888 99999 99999 re f Q

But after the fake-bold fix it became
   q 7 Tr
   q BT --PDF code for drawing "TEXT"-- ET Q
  -88888 -88888 99999 99999 re f Q

The only change here is q-Q bracket inserted around BT-ET but the
behavior of "pdf:code" has never changed.

The change of "text rendering mode" via "7 Tr" should be there as before
but the problem here is that the change of "clipping path" done in the block
enclosed by BT and ET is lost due to q-Q bracket recently added.

This addition of q-Q bracket around text block BT-ET does not affect
graphics state chages such as color change which come into effect
immediately when a graphics drawing operator is invokded but it affects
clipping path construction. At the time when the fill operator "f" is executed,
the clipping path should be that of "TEXT". But due to the "Q" operator
added immediately after "ET" (after the fake-bold fix), it is lost.
Due to which the whole page is filled with the current color. (for the original
example it is explicitly blue)


Thanks,
Shunsaku Hirata