BitmapText right-to-left line wrapping not working

[Ali-RS]

Line wrapping of a right to left text should be handled differently than left to right text. BitmapText wraps the right to left text in the same way it does for the left to right text.

See the forum for more info:
https://hub.jmonkeyengine.org/t/how-to-display-a-right-to-left-text-with-wrap-mode-with-bitmaptext/42148

[Ali-RS]

Added a simple test case into jme3-examples:

jmonkeyengine/jme3-examples/src/main/java/jme3test/gui/TestRtlBitmapText.java

Line 43 in 3d7a5ee

public class TestRtlBitmapText extends SimpleApplication {

The expected result should be:

                                                                   to right test a is This
                                                                                .text left 

but it displays:

                                                                  .text left to right test 
                                                                                 a is This 

[Aufricer]

I have started working on that. I may get the problem solved or at least contribute a 80 % solution.
As you see at least the first linewrap is at the right place.

Next days I will go on with the issue.
I will write a feedback (it worked, I could not do it) in a few days. If not, pls. tap me in the forum.

[pspeed42]

Just be aware that when making changes to BitmapText that the code is so awful that not a single person has managed to make a change to it without breaking at least one other use-case.

I have partially rewritten it locally but came across issues of trying to migrate the old loaders and stuff and then lost the time/motivation.

[Ali-RS]

@Aufricer, let's continue our discussion here

#1159 (comment)

Can you please push your changes to your GitHub page, so I can give it a try?

That's a Persian text I use. I suppose you need to enable Farsi language in your OS or something to properly display the text on your computer.

and in the case of JME, you need to use a Farsi bitmap font as well. You can use this bitmap font one:
yekan-font.zip

Edit (offtopic):
In RTL languages like Arabic/Persian depending on where a letter is (alone, stick to another letter from right or left), it may have a different shape (glyph).
For that I am using this utility class from https://github.com/RayanFar/bitMapFontCreator:

https://github.com/RayanFar/bitMapFontCreator/blob/95cfdd57956bf80186e6a80858552cf01e89fae2/bitMapFontCreator/src/utils/perisantext.java#L9

// A right to left text.
final private String text = perisantext.p("این یک متن آزمایشی می باشد");

Internally it also inverse the text.

[Aufricer]

I will push the changes asap as I feel I am finished.
If the shape of a letter is changing as well me realy need a new BitmapFont...

[pspeed42]

Keep in mind that when testing it with a font that's normally left to right that the kerning will all be backwards. I think right to left will only work with fonts meant to be right to left where the kerning was calculated properly for that direction.

[Aufricer]

Short feedback: Did working on alignment. Wordwrap is done. A lot of interrupted work.
Open:

• Need to check for letterwrap.
• Need to check for the kerning
  Kerning - as you see there is the issue (still) as pspeed42 has mentioned. Kerning is calculated to "0" always but I need to dive deeper to the issue. Have already some ideas.
  As soon as this one is done I will pull the changes to my JMonkey (github) repo. We might need a test with the persian or an arabic font. Might be possible, that Kerning is correct in the font so - adjusting for left to right text might be optional.
  I will be more detailed.

Blue Color = right to left text (text)
White Color = left to right text (text2) - to compare for position/alignement etc.
private String text = ".text left to right test a is This";
private String text2 = "to right test a is This text left.";

<Alignment center)

<Alignment right)

<Alignment left)

[Aufricer]

I have pushed my changes to my local JME3 repositiory.

Changed files are:

• Letters.Java
• LetterQuad.java
• BitmapText.java

It should work. But I have not yet tested it with a font that has tabs or offset or kernamount.
See the ToDos.

What would be the next steps ?

[Ali-RS]

Thanks, @Aufricer, going to try it soon and provide feedback.

[Ali-RS]

Works fine. But I noticed I need to reverse the text before setting it to BitmapText to properly display it. It seems the reverseText() step in BitmapText is extra. If I remove it, then the text displays properly.

I am going to try it with Lemur TextField as well.

Thank you so much :)

[Aufricer]

@Ali-RS
Thats the question I had for the reverse stuff. As I am not familiar with (written) Arabic or Persian at all I thought that writing the text starts from A to B to C like "CBA". Thats why I reverted the Input and thats the question in the toDo.
But if its not needed, we can keep the BitmapText.java untouched as well!

Looking forward to see a screenshot/result from Lemur.

PS: My wife saying the letters look OK (they are arabic as well) but she dont understand Persian.
So I guess it also looks correct with an Arabic sentence ?
Could you do a compare as I did (with left to right and right to left text) ?

[Ali-RS]

So I guess it also looks correct with an Arabic sentence?

Yes, the line wrapping and letter alignment are Ok, but all the letters are rendered in their single shape (unconnected), the same happens for Persian as well. As mentioned before in Arabic and Persian text a letter can have 4 different shapes based on its position in the word (stick to another letter from left, stick to another letter from right, stick from both sides (is in middle), or single (unconnected)) so an extra step is needed to be done for parsing the text and choosing the correct Glypgh code for that letter. Someone has made a parser for Persian text, a similar parser needed to be made for Arabic I guess. Later we may want to add an interface for the parser in the BitmapText itself.

This is how the Arabic sentence "بتحويل الكتابة العربي" looks currently. Despite from the unconected letters, everything else looks fine.

Could you do a compare as I did (with a left to right and right to left text)?

Not sure if I am understanding this. Do you mean I compare the right, left, and center alignment or something else?