[Lazarus] TSynEdit highlighter with simple spell-checker (almost working nicely)

[pascal_tom]

I want to share a simple solution to spell-checking with TSynEdit (Lazarus)
which I just implemented. It is super-simple, thus maybe trivial. However,
in my internet search I found that many people are seeking spell-checking
for Lazarus and Delphi, so this might help some people or even trigger the
development of a TSynSpellcheck component for being included to Lazarus.

It works already nice with English text (no umlauts) and almost nice in
German text (only words with umlauts are not highlighted).

Background and problem formulation:
As a university teacher I am building a small editor tool which should have
parallel spell checking for german and 


Solution:
======
 I found I nice trick to simply create a language spell-check for English
and German (should work for all languages basically):

1.) I use a TSynEdit (lazarus 1.8.4) and place a TSynAnySyn with it on my
main Form.

2.) I downloaded the English and German dictionary from hunspell
(LibreOffice), opened and merged them in Excel (with right codepage selected
to preserve German umlauts). In Excel I split the hunspell dictionary in two
columns, removed the unneeded second column and sorted the words
alphabetically (this speeds up the approach enormously). Then I saved it to
an UTF-8 encoded codepage to a file 'dictionary.txt' (double-checked this in
atom editor).

3.) At the opening of my main form I load this dictionary.txt file into a
TStringList which I then set as 'constants' or 'objects' in the
corresponding TSynAnySyn property that is set as a highlighter in my
TSynEdit. This process takes only 4-5 seconds on my 4 year old MacBookPro,
so that can be covered nicely by a splash screen at the start up of the
application.

Results:
======
Actually everything works out of the box, the text entering works fast and
all known words are highlighted.

Possible improvements:
=================
I think it is easy to add an 'add word to dictionary' feature as a context
menu. Maybe the reading of the dictionary can be even faster if the
dictionary is compiled into the app's executable as a resource and then be
read from there.

Still existing problems:
================
The only two problems I encountered and maybe some of the experts here may
help to improve :

- Words with german umlauts are not recognized. I think this is due to the
fact that these characters can not be added to the IdentifierChars property,
they are just replaced by question marks if one edits them to the string of
'!$&+,-./0123456789:;?ABCDEFGHIJKLMNOPQRSTUVXYZ_abcdefghijklmnopqrstuvwxyz'
that is set as a default there. I tried to add those characters also in the
code of TSynAnySyn, but it seems to be restricted to deal with only the
first 256 characters of the ASCII (or ANSI) table. I have to admit I do not
really know all these codepage-related things.

- It is a bit strange that the highlighter highlights correctly spelled
words (found in the dictionary) and not the other way around (marking
not-detected words with a little wave below, as usual). I found no way to
achieve this.

Any help from the community is appreciated, I would love to contribute this
approach as a coding example for lazarus, as it works at least nicely for
English words, but I don't know how/where I could upload the example code.






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