Re: [Plplot-devel] Bug fix to plbuf.c

[Jim D. <ji...@di...>]

> On Jun 11, 2015, at 12:29 AM, Jim Dishaw <ji...@di...> wrote:
> 
>> 
>> On Jun 10, 2015, at 11:30 PM, Alan W. Irwin <ir...@be...> wrote:
 <snip>
>> Just to confirm that I just now played a lot with resizing of
>> 
>> examples/c/x01c -dev xwin
>> 
>> for 5.10.0, 5.11.0, and git master tip (including your recent commit),
>> and I found no specific string issues for any of those cases.  So it
>> appears hard (at least with this example) to demonstrate a rendering
>> bug due to this issue that you just fixed, but your fix seems logical
>> to me (now) and certainly does not introduce any bad string rendering
>> that I can spot.
>> 
>> However, when doing those checks I did notice other resizing issues
>> that do need to be addressed.
>> 
>> 1. As a resize is occurring (typically by dragging one edge or one
>> corner of the GUI to make the whole thing smaller or larger) sometimes
>> the displayed GUI is a scaled plot and sometimes it is black (which is
>> OK).  But on some occasions when I stop resizing (by releasing the
>> mouse button) the result remains black for 5.11.0 and the master tip
>> version (which is not OK).  But 5.10.0 is fine in this regard. So this
>> issue is a regression introduced into PLplot between 5.10.0 and 5.11.0
>> and probably due to the flurry of changes you and Phil made in plbuf
>> before we released 5.11.0.
> 
>> 
>> Please verify the good result for 5.10.0 and bad result for 5.11.0,
>> git bisect to figure out what commit has caused the issue, and then
>> make the appropriate plbuf fix to get rid of this regression.
>> 
> 
> I think this problem is the plP_eop() that was inserted in the plRemakePlot() to make sure the BOP would perform as expected.  For the GUI drivers this will trigger another wait for input, which ends up blocking redraw messages.  I will verify by using git bisect.

I ran git bisect and the regression was introduced in the commit 1e402417c1f3e87c391fe428f936153c2a10e8cc

Author: Phil Rosenberg <p.d...@gm...>
Date:   Fri Feb 27 17:12:03 2015 +0000

    Fixed bug in rdbuf_di.
    
    Save cursubpage on replot
    call plP_eop() on replot which ensures that the first plP_bop() call actually does something.

If I comment out the plP_eop() that was added to plbuf.c in that commit, the xwin driver does not exhibit the problematic behavior.  I will investigate further on working on a patch.  I know why it is causing a problem, but it isn’t obvious to me how it gets to that point.