[skrifa] tthint: managing the graphics state #769
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Add implementations for the "managing the graphics state" group of TrueType instructions. See https://learn.microsoft.com/en-us/typography/opentype/spec/tt_instructions#managing-the-graphics-state
| //! | ||
| //! See <https://learn.microsoft.com/en-us/typography/opentype/spec/tt_instructions#managing-the-graphics-state> | ||
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| // 45 instructions |
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maybe this can be part of the mod docs?
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Makes sense. I'll update the other modules as well.
| self.graphics_state.zp0 = n.try_into()?; | ||
| Ok(()) |
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could just,
| self.graphics_state.zp0 = n.try_into()?; | |
| Ok(()) | |
| self.graphics_state.zp0 = n.try_into() |
I imagine?
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This ends up with a return type of () while the function expects Result<(), _> :(
| if !(1..=3).contains(&selector) || (value != 0 && value != selector_flag) { | ||
| return Ok(()); | ||
| } |
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what does it mean if the selector is out of this range? Is that an expected condition?
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Short answer is that we just ignore it.
The long answer is that FreeType has a "pedantic" mode that would fail here but I've never seen it enabled in practice because it breaks real fonts 🤷
This is something I'd like to spend more time investigating in the future... what I'd like to see is a run of the hinter with full error checking and then fall back to an unhinted glyph if it fails. I've also seen real world font bugs where running FT in non-pedantic mode leads to actual visual artifacts.
For now though, we stick with the status quo, for better or worse.
Add implementations for the "managing the graphics state" group of TrueType instructions (https://learn.microsoft.com/en-us/typography/opentype/spec/tt_instructions#managing-the-graphics-state).