Multiple topics here.
1. The view does size 100 paragraphs (Params.SLIDING_WINDOW_EXTENT) to ensure
smooth scrolling when text wrap is on. Initially I thought we could allow the
application to control this parameter, but we decided against it, as it exposes
internal aspect of the implementation.
2. You probably should not cache the paragraphs in the model, or try to
optimize the styling in the way I understood you did. When the view asks for
the paragraph, the model needs to render it in all its glory, or things would
break.
It looks you are trying to implement the syntax highlighting, right? The first
question you might want to ask is determine whether the styles are known at the
time when the paragraph gets requested. If not - you probably want to return a
plain text paragraph, that is with no styling, and once the styling is known,
fire the model's style change event, which will cause the view to request the
(newly updated) paragraphs it needs. In other words, the code you supplied
won't work - the model should always build a new paragraph (or supply a cached
one only if you can guarantee that nothing in it changed, not event line index).
3. Not sure about the scrolling, it seems to work on macOS as expected. Does
it work with a stock model that has none of the "optimizations"?
-andy
From: openjfx-dev <openjfx-dev-r...@openjdk.org> on behalf of PavelTurk
<pavelturk2...@gmail.com>
Date: Monday, April 28, 2025 at 16:54
To: openjfx-dev@openjdk.org <openjfx-dev@openjdk.org>
Subject: RichTextArea: How to return existing paragraphs from SyntaxDecorator?
I noticed that paragraphs in CodeArea are updated too aggressively. For
example, when I press a single key like '1', about 100 paragraphs get refreshed.
To improve performance, I decided to implement it this way: I store information
for each paragraph indicating whether its styles are up-to-date or not.
From SyntaxDecorator, I return the existing paragraph from the model if the
styles are valid. If the styles are outdated, I build a new paragraph.
Something like this:
codeArea.setSyntaxDecorator(new SyntaxDecorator() {
@Override
public RichParagraph createRichParagraph(CodeTextModel model, int
index) {
if (paragraphStylesAreValid) {
return codeArea.getModel().getParagraph(index);
} else {
RichParagraph.Builder b = RichParagraph.builder();
...
return b.build();
}
}
@Override
public void handleChange(CodeTextModel m, TextPos start, TextPos
end, int charsTop,
int linesAdded, int charsBottom) {
}
});
However, it didn't work because of this line -
https://github.com/openjdk/jfx/blob/3fdd21386d6db96294fcecd80afc25d09732c067/modules/jfx.incubator.richtext/src/main/java/jfx/incubator/scene/control/richtext/model/CodeTextModel.java#L83
As I result I get StackOverflowError. Could anyone say how to do it?
Best regards, Pavel
