Regression introduced by

https://cgit.freedesktop.org/libreoffice/core/commit/?id=cbe6c4929c9da28ce5553ce31782027d5111ed16

author		Tünde Tóth <tundeth@gmail.com>	2019-11-27 10:24:50 +0100
committer	Balazs Varga <balazs.varga991@gmail.com>	2020-04-28 08:02:59 +0200

"tdf#127811 tdf#127813 Introduce compatibility key for the data series"

Bisected with: bibisect-linux64-7.0

Adding Cc: to Tünde Tóth

@Szymon Kłos, Since you fixed bug 140489, I thought you might be interested in this issue

of course, the issue is fixed if ReverseSeriesOrderAreaAndNetChart is set to False
@Tünde Tóth, why ReverseSeriesOrderAreaAndNetChart is enabled by default ?

I looked into the example file (attachment 154579 [details]) of bug 127811

In 6.4 the area charts data series were in correct z-order on opening (matched PP), but in the legend the entries order was reversed. This is bug #127811

On save both the data series order and the legend entries order reversed when reopened in PP. This is bug 127811.

Now in 7.2 the area charts data series are in reversed z-order on opening (NOT matching PP), but the in legend the entries order now matches PP. This happens with the yellow area type data series in this attachment 169838 [details] example file.

On save the data series and legend entries order matches the original when the LO-saved file is opened in PP.

Another aspect of this fix:

The compatibility option was needed because the series order is different in ODF/OOXML.
The default value is there for maintaining the ODF-compatibility and the side effect is that OOXML opening changed as seen before.

Changing the compatibility option makes the OOXML area charts open just like in MSO, but in new charts created and saved&reopened to ODF the series z-order would look differently.

(In reply to NISZ LibreOffice Team from comment #5)
> Changing the compatibility option makes the OOXML area charts open just like
> in MSO, but in new charts created and saved&reopened to ODF the series
> z-order would look differently.

So we need the information in which "style" is the currently stored model and convert it accordingly to selected format on export.

fix: https://gerrit.libreoffice.org/c/core/+/114100

I found my fix in current state is not in mergable state.

Real problem is that MSO and LO are drawing series in different order:
           example: area chart has series 1 2 3 4
                    MSO draws series in order 1 2 3 4
                    LO draws series in order 4 3 2 1
                    LO and MSO draw legend in order 1 2 3 4

we have 3 possible solutions:
             1. "Do Nothing" (current approach in LO):
                legend is drawn correctly but chart areas
                in reversed order 
                - this bug will be present
             2. "Reverse series on MSO format import and export"
                chart areas are drawn correctly but legend
                in reversed order (MSO does that with ODF)
                - tdf#127811 will be again broken
             3. we introduce special chart view mode compatible
                with MSO to use with MSO formats
                (would be perfect, I tried this but requires
                 modifying all export filters to save correctly...)
                - all should be fine

I think 3rd option can cause new problems in export filters and make code more complex.
MSO has the same problem but with ODF where we draw in reversed order, they use solution 2. I think we could do the same. I think drawing chart area in correct order is more important that order of legend for data analysis. What do you think? Of course this will be workaround which will reopen tdf#127811 but close this bug instead.

Still reproducible in

Version: 7.6.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 424bdeda9fea09f0b48b5551baf872656845c7c3
CPU threads: 8; OS: Linux 5.10; UI render: default; VCL: gtk3
Locale: es-ES (es_ES.UTF-8); UI: en-US
Calc: threaded