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Reviewers

Summary

Support sub-pixel kerning and hinting for future support for improved character placement.
No user visible changes have been made.

Calculate sub-pixel offsets, using integer maths.
Use convenience functions to perform the conversions and hide the underlying values.
Use ft_pix type to distinguish values that use sub-pixel integer values from freetype and values rounded to pixels.

This was originally based on D12999 by @Harley Acheson (harley) with the user visible changes removed so they can be applied separately.

Even though it requires cumbersome conversion I think it's more reliable not to introduce floating point values for positioning text as it means positioning text may be less predictable, potentially run into float precision issues (this patch already has an assertion drawing widgets at certain zoom-levels because of a font-width calculation discrepancy).

Diff Detail

Repository

rB Blender

Branch

TEMP-BLF-64x-OFS (branched from master)

Build Status

Buildable 21573
Build 21573: arc lint + arc unit

Event Timeline

Campbell Barton (campbellbarton) requested review of this revision.Apr 7 2022, 4:08 AM

Campbell Barton (campbellbarton) created this revision.

Harbormaster completed remote builds in B21498: Diff 50191.Apr 7 2022, 4:08 AM

Don't ft_pix_to_int in the loop the assigns pixels

Harbormaster completed remote builds in B21499: Diff 50192.Apr 7 2022, 4:15 AM

Cleanup inline utilities, cast before bit-shifting

Harbormaster completed remote builds in B21500: Diff 50193.Apr 7 2022, 4:17 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 7 2022, 4:26 AM

Campbell Barton (campbellbarton) added a reviewer: Harley Acheson (harley).

Campbell Barton (campbellbarton) added a project: User Interface.

Campbell Barton (campbellbarton) added a subscriber: Harley Acheson (harley).

Remove _i suffix from advanced as it's no longer meaningful.

Harbormaster completed remote builds in B21501: Diff 50194.Apr 7 2022, 4:28 AM

Campbell Barton (campbellbarton) mentioned this in D12999: BLF: Float Positioning & Fix Hinting.Apr 7 2022, 4:37 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 7 2022, 4:43 AM

Re-order assignment.

Harbormaster completed remote builds in B21502: Diff 50195.Apr 7 2022, 4:46 AM

Remove duplicate define

Harbormaster completed remote builds in B21503: Diff 50196.Apr 7 2022, 4:54 AM

Nice! This is definitely more understandable than any of my attempts at directly using FreeType integer types like FT_F26Dot6 or FT_Pos.

Slight hinting is working correctly here. The best way to see that it is working right is to crank up Resolution Scale to 2, then when you change between None and Slight hinting you will see no horizontal change at all. This is correct in that Slight only aligns to the pixel grid vertically. Doing that with master you see lots of horizontal change. There is some movement at lower scales though that might be odd, but I'll look into that tomorrow.

Add comment describing the purpose of ft_pix
Use int32_t instead of int64_t - for our purpose int32_t is easily big enough.

Harbormaster completed remote builds in B21508: Diff 50202.Apr 7 2022, 8:19 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 8 2022, 12:08 AM

Use a doxygen section for the ft_pix API
Reference the file the macros originate.

Harbormaster completed remote builds in B21573: Diff 50317.Apr 11 2022, 4:14 AM

Campbell Barton (campbellbarton) mentioned this in D14633: BLF: Corrected Hinting.Apr 13 2022, 2:17 AM

Use rounding that matches 3.1 behavior (functional changes can be applied separately).

Harbormaster completed remote builds in B21613: Diff 50387.Apr 13 2022, 2:44 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 13 2022, 2:50 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 13 2022, 2:56 AM

Improve commens, rename advance to advance_x

Harbormaster completed remote builds in B21614: Diff 50389.Apr 13 2022, 3:44 AM

Campbell Barton (campbellbarton) retitled this revision from BLF: Sub-pixel positioning & fix hinting to BLF: sub-pixel positioning support.Apr 13 2022, 3:46 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)

Minor cleanup to comments & calculaiton for advance in blf_font_boundbox_foreach_glyph_ex.

Harbormaster completed remote builds in B21615: Diff 50390.Apr 13 2022, 3:55 AM

From discussing this with @Harley Acheson (harley), he's fine to apply this patch and make further hinting changes ontop of it.

Harley Acheson (harley) mentioned this in T94030: Font Changes (Parent Task).Apr 13 2022, 4:18 AM

Committed rBae43872ad572eb3e6ad1ebfd02921fc2403059bc, closing.

Campbell Barton (campbellbarton) mentioned this in rBae43872ad572: BLF: sub-pixel positioning support.Apr 13 2022, 5:10 AM

Campbell Barton (campbellbarton) abandoned this revision.Apr 14 2022, 9:27 AM