High performance text component

André Thieme a.thieme at freenet.de
Thu Aug 2 19:52:19 PDT 2012

I would like to develop an editor component, think of NetBeans/Eclipse.
There should be a surface on which one can display sharp LCD text. Lots
of text. Users may wish to open 40 MB .csv files, perhaps on top of 200
opened code files, of which some may contain 8k LOC.

So far I have thought about different strategies:

1) A Group filled with javafx.scene.control.Label or
javafx.scene.text.Text instances. This makes it very easy to detect
where exactly a user clicked. It allows for giving each word or even
symbol its own color, font, style, etc.

This is obviously a difficult approach. The corresponding scenegraph
might contain hundreds of thousands of nodes and won’t perform well.

2) WebViews.
Those allow us also to colorize and style each word or symbol. But I do
not know yet, how much control it will give me. Can I overlay words with
my own graphics? For example, I may want to draw a pulsing elipse around
a specific word, to draw the attention of the end user to it. I would
have to know the exact coordinates of each single words. The bounds so
to speak, baseline, etc.

Also: how well do WebViews scale if I have 200+ of them in a ScrollPane?

3) Canvas + fillText
I tried this one, and it is pretty performant. On my laptop I can write
15k words on a big Canvas in only 30 msecs. Unfortunately Canvas can at
the moment only use “Gray” as Font smoothing style, not “LCD”. But while
this may come in future versions it has two other limitations:
it does not deliver boundaries information when fillText is called. So I
was forced, in my experiments, to first setText a Text component, get
its layout bounds, and then calculate the coordinates for fillText.
The second limitation is the most difficult one: a Canvas is limited to
8192x8192 pixels resolution. With a small font this would be good for
about 700 LOC.
So, the Canvas that I would need should allow 1mio x 1mio resolution.
An alternative technique would be to have hundreds of smaller Canvas’,
in Google Maps style, and put them together somehow.

All those alternatives don’t look really usable for me.
One thing that would be interesting is to have access to low-level
functions of the JFX API. How does a javafx.scene.text.Text instance
paint its LCD text on the screen?
In principle what I would need is an infinite surface on which I can
write and manipulate text with maximum speed, without adding nodes to
the scenegraph. Modern video cards can run 3d games with way over 60 FPS
and render complex scenarios with light. It should be possible to
display text that is at least as fast (I know that JFX caps at 60 FPS,
but that is fine). So when I have a massive 30 MB file with hundreds of
thousands of lines of text, all colored and styled depending on the
file type (Java code, Python code, etc), and this should scroll and
resize very fluid.

If the JFX team wanted to write the editor component for Eclipse 5,
how would you approach that? Most likely not by using one of the three
strategies that I layed out above.

Do you have any inputs for me?

Sunny greetings,

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