Tamil fonts: two characters rendered as one |
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Issue description
Chrome Version : 56.0.2924.87
OS Version:
URLs (if applicable) :
Other browsers tested:
Add OK or FAIL after other browsers where you have tested this issue:
Safari 5: OK
Firefox 4.x: OK
IE 7/8/9: Not tested
** What steps will reproduce the problem?
1) Copy paste "க்க" on any Google property
2) Put the cursor at the end of the text.
3) Move the cursor left - you will observe that the cursor would pass both the characters together (க் & க).
** What is the expected result?
Cursor should only traverse க when moved one character left.
** What happens instead of that?
When a pure consonant, (eg: க் - k), is followed by a vowel+consonant (eg: க - ka) character, the two characters are rendered as one character (or a single compound glyph). These should be rendered as two separate characters (or glyphs).
While this kind of rendering is correct for other Indic languages, Tamil is an exception because it doesn't compound glyphs to form a single glyph when combining a pure consonant with a vowel+consonant combo.
** Please provide any additional information below. Attach a screenshot if
possible.
UserAgentString: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36
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Feb 17 2017
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Feb 17 2017
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Feb 17 2017
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Feb 20 2017
This is a selection bug; we shape "க்க" as 3 glyphs, 2 clusters. Probably the grapheme cluster logic in the selection considers this as a grapheme, but as per UAX#29, this should be 2 grapheme.
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Feb 22 2017
> Probably the grapheme cluster logic in the selection considers this as a grapheme, but as per UAX#29, this should be 2 grapheme. Perhaps because HarfBuzz reports this as one cluster. I think our selection code does not handle that. One can also try with a simple "fi" ligature.
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Feb 22 2017
HarfBuzz is correct as far as I checked in my debugger; unfortunately our editing/selection doesn't use cluster info from HarfBuzz yet; it uses its own logic. This in on the backlog for editing team.
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Mar 8 2017
So, any updates or ETA for this? This is pretty annoying for someone who types in Tamil language.
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Apr 26 2017
Issue 675478 has been merged into this issue.
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May 16 2017
Possible rootcause as mentioned in Issue 675478 : https://bugs.chromium.org/p/chromium/issues/detail?id=675477
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Jul 26 2017
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Oct 4 2017
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Oct 16 2017
This is probably the same root cause as Issue 473476
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Dec 2 2017
i tried, this bug is reproducible in Windows 10 and Mac OS X High Sierra.
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Dec 4 2017
Agree that this is likely the same as issue 473476 . fserb@, can you confirm, and mark as duplicate if appropriate?
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Dec 5 2017
This isn't a ligature; see #5: > we shape "க்க" as 3 glyphs, 2 clusters.
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Dec 22 2017
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Jan 2 2018
Will be fixed in Chrome 65: https://chromium-review.googlesource.com/c/chromium/src/+/843461
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Jan 3 2018
The following revision refers to this bug: https://chromium.googlesource.com/chromium/src.git/+/60a12c281f9c177383b3bcad8c6459dac6e07f25 commit 60a12c281f9c177383b3bcad8c6459dac6e07f25 Author: Ryan Landay <rlanday@chromium.org> Date: Wed Jan 03 03:37:08 2018 Allow splitting grapheme clusters after Tamil virama We currently don't allow grapheme clusters to be split after Indic virama characters (this seems to be a custom deviation from the grapheme cluster rules in UAX #29). According to a Googler familiar with Indic languages, this behavior is correct for other Indic languages, but not for Tamil ("Tamil is an exception because it doesn't compound glyphs to form a single glyph when combining a pure consonant with a vowel+consonant combo.") This is causing at least two problems: 1. It's not possible to put the insertion point between certain pairs of Tamil characters when typing ( crbug.com/693687 ). 2. Inputting Tamil with phonetic keyboard IMEs is super broken ( crbug.com/675477 ). This CL fixes both of these problems by treating the Tamil virama character differently from other Indic viramas. Note: this does *not* address the issue in crbug.com/792713 where the Tamil handwriting IME on Android inserting lone SpacingMark characters triggers odd behavior. Bug: 675477 , 693687 Change-Id: Iae95e70418aeadcbab5296245ad7253cf3c31cde Reviewed-on: https://chromium-review.googlesource.com/843461 Reviewed-by: Emil A Eklund <eae@chromium.org> Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org> Commit-Queue: Ryan Landay <rlanday@chromium.org> Cr-Commit-Position: refs/heads/master@{#526611} [modify] https://crrev.com/60a12c281f9c177383b3bcad8c6459dac6e07f25/third_party/WebKit/Source/core/editing/ime/InputMethodControllerTest.cpp [modify] https://crrev.com/60a12c281f9c177383b3bcad8c6459dac6e07f25/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtil.cpp [modify] https://crrev.com/60a12c281f9c177383b3bcad8c6459dac6e07f25/third_party/WebKit/Source/core/editing/state_machines/StateMachineUtilTest.cpp |
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Comment 1 by siddaarths@google.com
, Feb 17 2017