The FreeType Project - Bugs: bug #50470, No means to create unhinted size.
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bug #50470: No means to create unhinted size.
Submitter: | bungeman <bungeman> | ||
Submitted: | Mon 06 Mar 2017 07:01:55 PM UTC | ||
Severity: | 3 - Normal | Item Group: | Incorrect behaviour |
Status: | Fixed | Privacy: | Public |
Assigned to: | wl | Open/Closed: | Closed |
Planned Release: | 2.8 |
Jump to the original submission
Fri 28 Apr 2017 06:41:20 AM UTC, comment #26: |
Werner LEMBERG <wl> |
Fri 14 Apr 2017 01:52:05 PM UTC, comment #25: Looking at your fine test page in Firefox, have you noticed the differences between the page and its print preview? The right waterfall edge is nice and smooth in the print preview and somewhat jagged in the actual page. So this is not exactly WYSIWYG, but not too bad.
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Alexei Podtelezhnikov <podtelez> |
Thu 13 Apr 2017 02:47:17 PM UTC, comment #24: I just looked at before/after of PDF output of Chromium with both Sans and Mono fonts. The only change with the patch is the fix for the buggy kerning. No other metrics seem to change. |
Adam Goode <agoode> |
Thu 13 Apr 2017 03:43:12 AM UTC, comment #23:
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Alexei Podtelezhnikov <podtelez> |
Wed 12 Apr 2017 03:13:24 PM UTC, comment #22: There is at least 1 report of the height being increased after the change:
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Adam Goode <agoode> |
Wed 12 Apr 2017 02:35:26 PM UTC, comment #21: The y_scale used to be adjusted twice to achieve the integer ppem first and then to fit the blue zone to the grid. The combined rounding error sometimes led to pleasantly inflated x-height. Now we omit the first step and the error is smaller actually. What is there to fix?
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Alexei Podtelezhnikov <podtelez> |
Tue 11 Apr 2017 10:16:55 PM UTC, comment #20: Alexei: thanks for tracking that down. Do you think there might be a small autohinter tweak that could be made to keep the old behavior? I think trying to preserve the existing metrics is worth it, just to avoid unnecessary churn with people's font settings. |
Adam Goode <agoode> |
Mon 10 Apr 2017 02:26:39 AM UTC, comment #19: So the pango example corresponds to
with light/autohint rendering. So, hinting vertically only, the autohinter switched from rounding up to rounding down. It actually looks like the switch is arbitrary (right or wrong) because the unhinted glyphs are close to the middle. The native hinter, by the way, did not change the rounding direction, which stays down. There is actually less difference between native and auto- hinters now.
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Alexei Podtelezhnikov <podtelez> |
Thu 06 Apr 2017 11:59:01 PM UTC, comment #18: Thanks, pango-view reproduces the problem nicely.
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Adam Goode <agoode> |
Thu 06 Apr 2017 02:40:35 PM UTC, comment #17: Hi, I'm able to reproduce the issue by running " pango-view --dpi 96 --font "monospace 11" --text "HelloWorld!" ".
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Marek Kašík <mkasik> |
Wed 05 Apr 2017 10:08:46 PM UTC, comment #16: This is with DejaVuSansMono.ttf, probably at size 13. I only could reproduce it in Gnome, not with ftview. |
Adam Goode <agoode> |
Wed 05 Apr 2017 09:10:17 PM UTC, comment #15: We are back to square one. The rationale for the original fix in 2011 was to fix ascend, descend, and line spacing values and it worked for any font. |
Alexei Podtelezhnikov <podtelez> |
Wed 05 Apr 2017 07:55:12 PM UTC, comment #14: I don't use Gnome, sorry.
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Werner LEMBERG <wl> |
Wed 05 Apr 2017 06:23:01 PM UTC, comment #13: Fedora cherrypicked the patch, and some users are reporting font rendering changes (some glyphs are now vertically squashed).
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Adam Goode <agoode> |
Thu 30 Mar 2017 11:20:41 AM UTC, comment #12: My concerns were unfounded, I think. It seems that over the years other changes fixed the metrics issues. Just reverting the old patch appears to work just fine, so I've done it right now.
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Werner LEMBERG <wl> |
Tue 21 Mar 2017 07:22:42 PM UTC, comment #11: No, there's a real bug, which is non-trivial to fix: Due to the copying of the rounded values in `TT_Size' to the `FT_Size' structure it is no longer possible to get real linearly scaled metrics – they are using the rounded x_scale and y_scale values...
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Werner LEMBERG <wl> |
Tue 21 Mar 2017 06:52:56 PM UTC, comment #10: This sounds like a WYSIWYG problem: you need to somehow synchronize the layout for two devices with different resolutions, with hinting on one of them, so that both look good.
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Alexei Podtelezhnikov <podtelez> |
Thu 16 Mar 2017 07:59:20 PM UTC, comment #9: For context, here is the original Chromium bug report:
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Adam Goode <agoode> |
Thu 16 Mar 2017 07:30:10 PM UTC, comment #8: |
Alexei Podtelezhnikov <podtelez> |
Thu 16 Mar 2017 03:27:36 PM UTC, comment #7: Thanks for the detailed report. I agree that there is a bug.
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Werner LEMBERG <wl> |
Thu 16 Mar 2017 02:49:37 PM UTC, comment #6: The issue here is that the rounding happens in the FT_Size, so there appears to be no way to control it. It throws away information too early. If I just want unhinted outlines or metrics out of a font that has this bit set and ask FreeType for them at a size of 9.3, FreeType won't do that because it lost the 9.3 and converted it to 9.0 before I could ask for the outlines. Since this affects the FT_Size it affects everything, not just the bitmaps.
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bungeman <bungeman> |
Tue 14 Mar 2017 06:33:12 PM UTC, comment #5: Sorry about too much noise.
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Alexei Podtelezhnikov <podtelez> |
Tue 14 Mar 2017 01:52:18 AM UTC, comment #4: Please describe what you want to achieve.
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Alexei Podtelezhnikov <podtelez> |
Mon 13 Mar 2017 09:16:05 PM UTC, comment #3: Just to be clear, the fact that linearHoriAdvance doesn't work as expected is not the entire issue here (though it is part of it). The 'only at integer sizes' bit should only be respected when running bytecode hints and should be completely ignored otherwise. Even when running bytecode hints it should be ignored for anything with 'linear' in the name. |
bungeman <bungeman> |
Mon 13 Mar 2017 09:11:31 PM UTC, comment #2:
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bungeman <bungeman> |
Mon 13 Mar 2017 06:16:24 PM UTC, comment #1: Fedora never patched it out.
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Alexei Podtelezhnikov <podtelez> |
Mon 06 Mar 2017 07:01:55 PM UTC, original submission:
The change http://git.savannah.gnu.org/cgit/freetype/freetype2.git/commit/?id=b0962ac34e66052ccfee7996e5468f30d4bd5a72 "Fix copying metrics
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bungeman <bungeman> |
Depends on the following items: None found
Items that depend on this one: None found
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Follow 9 latest changes.
Date | Changed by | Updated Field | Previous Value | => | Replaced by |
---|---|---|---|---|---|
2017-04-13 | agoode | Attached File | - | Added crbug696356.html, #40392 | |
2017-03-30 | wl | Status | Confirmed | Fixed | |
Open/Closed | Open | Closed | |||
Planned Release | None | 2.8 | |||
2017-03-16 | podtelez | Carbon-Copy | - | Added behdad | |
2017-03-16 | wl | Item Group | Wishlist | Incorrect behaviour | |
Status | None | Confirmed | |||
Assigned to | None | wl | |||
2017-03-07 | agoode | Carbon-Copy | - | Added agoode |
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Corresponding source code
Here you can find an extensive explanation of the problem.
http://lists.nongnu.org/archive/html/freetype-devel/2017-04/msg00042.html