[LyX/2.3.x] Attempt to fix #11457

[Richard Kimberly Heck]

commit b1860e301acfef3586143d240ae00716beb8c61c
Author: José Matos <jamatos at lyx.org>
Date:   Tue May 28 16:22:32 2019 +0100

    Attempt to fix #11457
    
    In python 3 the colors need to be strings and not bytes:
    
    This was the equivalent of
    
    >> print("%s" % b"1")
    "b'1'"
    
    since the colors were bytes the call to dvipng was something like
    
    dvipng -Ttight -depth -height -D 115 -fg "b'rgb 0.937255 0.941176 0.945098'" -bg "b'rgb 0.137255 0.149020 0.160784'"  "lyxpreviewxBJEqm.dvi"
    
    Note the "b'rgb after both -fg and -bg that wrecked havoc and thus dvipng failed. That was the difference between python2 and python3 calls.
    
    (cherry picked from commit 8dd31803b16d1fb6b30772955188c3595437f64a)
---
 lib/scripts/lyxpreview2bitmap.py |    6 ++++++
 status.23x                       |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/lib/scripts/lyxpreview2bitmap.py b/lib/scripts/lyxpreview2bitmap.py
index e4bf131..ecefdaf 100755
--- a/lib/scripts/lyxpreview2bitmap.py
+++ b/lib/scripts/lyxpreview2bitmap.py
@@ -373,6 +373,7 @@ def main(argv):
     dir, latex_file = os.path.split(input_path)
 
     # Echo the settings
+    progress("Running Python %s" % str(sys.version_info[:3]))
     progress("Starting %s..." % script_name)
     progress("Output format: %s" % output_format)
     progress("Foreground color: %s" % fg_color)
@@ -394,6 +395,11 @@ def main(argv):
     fg_color_dvipng = make_texcolor(fg_color, False)
     bg_color_dvipng = make_texcolor(bg_color, False)
 
+    # For python > 2 convert bytes to string
+    if not PY2:
+        fg_color_dvipng = fg_color_dvipng.decode('ascii')
+        bg_color_dvipng = bg_color_dvipng.decode('ascii')
+
     # External programs used by the script.
     latex = find_exe_or_terminate(latex or latex_commands)
     bibtex = find_exe(bibtex or bibtex_commands)
diff --git a/status.23x b/status.23x
index a9f8233..93202c5 100644
--- a/status.23x
+++ b/status.23x
@@ -162,6 +162,8 @@ What's new
 
 - Fix TeX file listing with the Nix package manager.
 
+- Fix Python detection routines, and so instant preview on some platforms
+  (bug 11282).
 
 
 * DOCUMENTATION AND LOCALIZATION