> On 14 Sep 2016, at 02:23, Scott Kostyshak <skost...@lyx.org> wrote:
> 
> On Tue, Sep 13, 2016 at 07:14:00PM +0100, Stephen Luttrell wrote:
>> I have OS X 10.11.6 and LyX 2.2.1 with (1) Look & Feel / Display / Display 
>> graphics checked, and (2) Look & Feel / Display / Instant preview set to 
>> “On”.
>> 
>> If I open Help / Specific Manuals / LilyPond, then after a short delay the 
>> various LilyPond insets — these are inside Preview insets, such as in 
>> section 2.3 on Previews — display themselves in the LyX window as blank 
>> regions, whereas I would have expected fragments of musical score to appear. 
>> However, when I view the corresponding PDF the music is displayed correctly, 
>> but it would be really nice for the Preview insets to work as expected in 
>> the LyX window.
>> 
>> In case it is relevant, preview of mathematical formulae in my LyX window 
>> works correctly.
> 
> Hi Stephen, I'm not sure what's wrong. I just checked and the previews
> show up fine on Ubuntu so there might be something platform-specific
> going on. Hopefully there's someone around here who uses Mac that can
> check.


With a lot of outside help from Helge Hafting, we managed to narrow down what 
the LilyPond Preview problem might be due to.

LilyPond previewing depends on LyX successfully converting EPS graphics (of 
each musical score fragment) into PNG graphics. To make this conversion process 
as similar as possible to the way it is done in Linux, where LilyPond 
previewing is known to work, I installed MacPorts on my Mac, which installs 
ImageMagick as part of the MacPorts installation process. I then reconfigured 
LyX, which then set up a new converter EPS -> PNG using the command “convert 
$$i $$o”, where “convert” is part of the ImageMagick installation. I verified 
that “convert filename.eps filename.png” creates the expected PNG file from one 
of the temporary EPS files that LyX creates when trying to preview a LilyPond 
inset. However, LyX itself still displays blank regions rather than the 
expected fragments of musical score in its window, and when I check the 
temporary PNG files that LyX has generated from the temporary EPS files they 
all contain the same blank pieces of graphics. I have closed then opened LyX, 
and I have even rebooted, but this problem persists.

So, I have a working “convert”, but LyX fails to use it for the EPS previews 
generated by LilyPond insets. BTW, I checked that if I insert EPS graphics into 
a LyX document, then this does display correctly in the LyX window, so there is 
something not working with LilyPond insets, rather than with EPS graphics 
generally.

In case it is relevant, there is only one “convert” on my Mac, which is the one 
that appeared after I installed ImageMagick, and there are 3 EPS converters set 
up in my LyX installation, which are (1) EPS -> PDF (graphics) using “epstopdf 
--outfile=$$o $$i”, (2) EPS -> PNG using “convert $$i $$o”, and (3) EPS 
(uncropped) -> EPS using “ps2eps -- < $$i > $$o”.

Stephen Luttrell

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