SynEdit highlighter attributes dynamically changing
lazarus / 31-LCL

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staratel20 · 2016-03-21 08:00

Good day.

Analyze the code of [beautiful] example code
'...\SynEdit\NewHighlighterTutorial\' I successfully write my own
highlighter. But for my goal I need to dynamically change attributes
of ONE highlighter (including Attribute.Name and Attribute.Caption).
Fist I think it's very easy - I simple write something like:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
MyHighlighter.Clear;
and again add needed attributes. But ... no method 'Clear' in
TSynCustomHighlighter class. I try to modify unit SynEditHighlighter
and add it method Clear:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TSynCustomHighlighter.Clear;var  i:integer;begin  i:=0; 
while(i<AttrCount)do  begin    fAttributes.Objects[i].Free;   
fAttributes.Objects[i]:=nil;  inc(i);  end;  fAttributes.Clear;end;
I expect, that after call this method and then - MySynEdit.Update (or
something) all will looks good, but it's don't.

Also want to notice, that would be intuitively if present method
AddAttribute - than present also method DelAttribute. Absent of such
method looks some weird.

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Martin_fr · 2016-03-21 19:38

I dont know what you want to archive, and if a highlighter is the best
solution (there is an alternative concept called Markup).

Normally Attributes are typical to the structure of the document. So
they never change. This is way there only is an Add method.

You can remove all of them by calling FreeHighlighterAttributes
(usually done in Destroy)

Since adding is only expected during creation, and freeing only in
destroy, neither of them will trigger any updates.


Reviewing the sample code, I found it has a bug. The following is
missing (I will commit that asap to svn)

 Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  // Ensure
the HL reacts to changes in the attributes. Do this once, if all
attributes are created  SetAttributesOnChange(@DefHighlightChange); 
If you add or remove attributes, then try to call
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
 DefHighlightChange();that should trigger a rescan, and also get
SynEdit to repaint.

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staratel20 · 2016-03-22 06:28

QuoteIf you add or remove attributes, then try to callbut how can I
remove attributes? In the class TSynCustomHighlighter is exist only
method AddAttribute and I don't see something like
Delete(IndexAttr:integer) or RemoveAttribute(IndexAttr:integer)

Also I think that in class TSynCustomHighlighter intuitively must to
be exist method Clear(which means - delete all attributes).

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Martin_fr · 2016-03-22 12:01

You can only remove all of them.

Well, maybe you can get away, and skip AddAttribute. You can then
store them in your own List and have full control.

All the Attribute related functions are virtual, so you can override
them as needed.

What are you trying to archive? Maybe there is another solution?

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Edson · 2016-03-22 14:26

FreeHighlighterAttributes, works well to delete all the attributes.

I would like to know too: Why would you need to delete an specific
attribute?

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staratel20 · 2016-03-22 16:09

Edson: in my situation I need exactly - delete all attributes. Thank
you for 'magic function' FreeHighlighterAttributes - exactly what I
need. Honestly I ask myself - why not called simple - 'Clear' - first
name the user(developer) will looking for, if will need to clear all
attributes. And then, when not find - go to documentation(or forum) to
discover FreeHighlighterAttributes )). In my inherited highlighter
class I define method 'Clear' with only one instruction with this
procedure.

Bay the way - think way not good to naming property AttrCount -
CountAttr look more pretty. When user will writing some code and type
dot(and helper list appeared) - no need to remember 'Count of what?' -
enough to know that need 'count of something' , and when begin type
'count...' in helper list he see - 'of cause - CountAttr'. I use this
naming rule all my life and it's very, very comfort to use. Maybe in
Lazarus already exist another naming agreement(I don't know) - only
say what I think to make Lazarus better.

Martin_fr: thank you for advises, but when I write finally code with
Edson method it also work when I remove
Code: [Select]SetAttributesOnChange(@DefHighlightChange);I don't know
why but work).

Thanks for all your answers.

Oops, almost forgot...
QuoteI would like to know too: Why would you need to delete an
specific attribute?at this time I write search engine which will
highlight founded words. So, what if you want to change background of
word on mouse over? But really my task - absolutely not mater, as
wrote Ray Konopka in his book(not pretend at quote): "You can't even
imagine for which purpose user can use your component".

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Edson · 2016-03-22 16:53

Quote from: staratel20 on March 22, 2016, 05:09:41 pmThank you for
'magic function' FreeHighlighterAttributes - exactly what I need.

In fact, that function was mentioned by Martin.

Quote from: staratel20 on March 22, 2016, 05:09:41 pmat this time I
write search engine which will highlight founded words. So, what if
you want to change background of word on mouse over?

I'm not sure, but I have the feeling this is a work for Markups.

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staratel20 · 2016-03-22 18:57

Quotethat function was mentioned by MartinI'm also thanks to Martin.
But function name some confused me, so I don't found at once.

QuoteI have the feeling this is a work for MarkupsIn future - maybe,
who knows. But not this time. This time I need it for exactly what I'm
wrote above.

Also want to ask - is exist easy way to modify my attached code to
highlight not only whole words, but also a part of words. I look to
example 'SynPositionHighlighter' and it's not looks simple. But if it
simplest way - I'll go look further.

P/s: Also will glad to see this(or modified) code in repository
examples if it needed. Think it easy as it can be.

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Edson · 2016-03-22 19:56

Quote from: staratel20 on March 22, 2016, 07:57:10 pmAlso want to ask
- is exist easy way to modify my attached code to highlight not only
whole words, but also a part of words.

A highlighter "highlights" tokens. The rules to extract tokens, are
defined in the highlighter. If your highlighter  includes the logic to
recognize part of words like tokens, then it will highlight part of
words.

I see in your code, an strange way to highlight words. You are
creating an attribute for each word. Normally many words share the
same attribute.

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Martin_fr · 2016-03-23 02:11

I had a quick look at it. If I read it correctly, then what you try to
do is similar to http://wiki.lazarus.freepascal.org/New_IDE_features_s
ince#Multiple_user_defined_word_highlight.2Fmarkup
(And it can do partial words too)

Only that you will have an individual color for each word, instead of
groups. And that would mean many instances of the markup, and be quite
slow.

About your code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
TFindContentHL.GetTokenAttribute: TSynHighlighterAttributes;... 
while(i<Self.AttrCount)do  begin    s:=
LowerCase(Self.Attribute[i].Name);    sc:=LowerCase(copy(FLineText,
FTokenPos,  sc is the same in each iteration of the loop. So calculate
it upfront.
Ideally use a binary search.

Or if you want to go for partial words anyway, copy and adapt

Or use TSynSearchDictionary from unit syneditmarkuphighall.pp
IIRC it uses
https://en.wikipedia.org/wiki/Aho%E2%80%93Corasick_algorithm for the
search. It can find any token, even as part of a word.

The Markup it that unit stores search results. That is only needed if
words can match across line bounds. Otherwise you can scan each line
on request.

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staratel20 · 2016-03-23 07:19

Thanks for replies. Now in thinking how to screw the wheels to all of
that to make it go).

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staratel20 · 2016-03-25 13:16

Let me ask one more thing... In Lazarus Aho-Corasick algorithm already
implemented, or used more simple algorithm? And in which module it
implemented(of cause I can found by myself, but maybe somebody
remember it) ?

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Martin_fr · 2016-03-25 15:30

Quote from: staratel20 on March 25, 2016, 02:16:48 pmLet me ask one
more thing... In Lazarus Aho-Corasick algorithm already implemented,
or used more simple algorithm?

 TSynSearchDictionary from unit syneditmarkuphighall.pp

It can still be optimized for memory footprint (if you have
dictionaries with thousands of words). But it will work as it is, and
it will be way better than stringlist.

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staratel20 · 2016-03-25 18:07

Thank, I'll look there. So many new interesting information.