[Enhancement] Thumbnail presentation

[JoelGardes]

For increasing graph lisility, here are two enhancements using imagemagick's convert properties

1. non graphical files
   Adding file name in a empty bitmap
   General syntax :
   "convert -pointsize 36 -fill red -background white label:<file_name> ../thumbnails/<index_name>.png"
   including subdirectories names of main directory
   but with discrete and tasteful colors

2. graphical files
   Adding files name label to thumbnail
   General syntax to add to present convert command:
   "label:'<initial_filename>' -gravity Center -append"

<initial_filename> does not contain directory path, other option stays unchanged.

Joined : produced exemples

Non graphical:

Graphical:

[JoelGardes]

Forgotten to add to backlog, sorry!

[ChristopheMaldivi]

About initial_filename:

• it is not the internal ID filename, but rather the original filename which could be a mess: with specials chars not easily supported by tools (graphviz or image magic)
• so instead of using initial_filename directly, we will display the url encoded version

For instance:

• "chat" => "chat"
• "château" => "ch%C3%A2teau"

Easiest way to support all special chars, with something which is still readable. And no impact for files containing no special chars.

[JoelGardes]

Comment : Stuffs for string names problems in GraphViz :

Authorized chars for IDs:

• Any string of alphabetic ([a-zA-Z\200-\377]) characters, underscores ('_') or digits ([0-9]), not beginning with a digit;
• a numeral [-]?(.[0-9]+ | [0-9]+(.[0-9]*)? );
• any double-quoted string ("...") possibly containing escaped quotes ('")1;
• an HTML string (<...>).

Tested : <arc-en-ciel> works well in neato, by displaying the string "arc-en-ciel" (but a node named arc-en-ciel is forbidden).

This does not resolve the problem with directories names, but could be perhaps helpful for file_names retrieving when computing graph.

[JoelGardes]

Problem : no file_name included in thumbnails (missing label)... just a convert of graphical files

[JoelGardes]

issue #42