[Evaluate] Fix RTL text scrolling (1 Viewer)

[bob987]

This patch fixes some of the problems concerning the scrolling of text with right to left characters in it.

Currently RTL text scrolls in a very strange way (see Strange Hebrew text scroll )
With this patch the RTL text will scroll continually to the right in a smooth way without jumping.

This bug fix will improve all the RTL language users UI Experience



There is still some work to be done concerning the RTL scrolling:
A) In mixed text (LTR & RTL) when a new LTR word appears its characters will appear in the wrong order ("hello" will not appear h->e->l->l->o but o->l->l->e->h). This also the case with the current text scrolls.

B) When the RTL scrolling text appears, the right most part of the text is already trimmed from the screen. The text should appear with its right most part aligned to the right side of the text box.

C) RTL scrolling text should have the fade effect in the left side of the text box.
I will try to solve A in the future. B+C are probably over my ability.

Hope this will get into RC2,
Bob

 

[bob987]

Probably most of the dev guys don’t have a system with RTL language installed, so I made two short avi to let you see the bug and the fix.
There are 3 scrolling texts:
a) Only LTR.
b) RTL + LTR
c) Only RTL
Movie recorded using horizontal scroll speed=4

Bob

 

[bob987]

I've updated the patch to RC2 (no changes in the code) for my own use so I send the updated file.

Is there some thing I can do to help this get into the next release?

Bob

 

[muellers]

AW: Fix RTL text scrolling

Hi,

will this patch include in Release 1.2?

greets

 

[elliottmc]

Hi,

I can't test this myself, but from the videos provided, it seems that it would be good to include it.

Perhaps one of the developers could build binaries for testing?

As long as it doesn't cause any problems, it is probably safe to commit.

Mark

 

[thecode]

I've tried to test it with the SVN version r27641 but for some reason live TV stopped working for me (some index out of bounds)
The patch does solve the scrolling bug, Since I've done some changes to my version also and had to merge files might be problem on my side.
I'll try over the weekend to do clean patch on the latest SVN and publish my conclusions.

thecode

 

[thecode]

I tried testing the patch, it does work, but I'm sad to say it doesn't fix all situations.
If the test has mixed RTL text and LTR text it will not scroll correctly at all.
In mixed text it should scroll as it has only RTL text.
I hope to have time to fix that, but if it is not fixed I suggest waiting with the patch (Altought is still fix some situations and doesn't cause problems).

thecode.

 

[bob987]

Hi
I know that this code only fixes RTL only texts.
I tried to fix the mixed text situation but to do this there is a need to rewrite all the text handling code (which is over my capabilities).
I do think that this patch will improve the current code and should be implemented in V1.2

For V2, it will be a big improvement to use the internal window API for text printing. there is a very complex logic with mixed LTR + RTL text, and windows does a great job in this area.

Bob