add support for creating variation fonts #20
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src/font_face.rs
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| pub fn has_variations(&self) -> bool { | ||
| unsafe { | ||
| let face5: Option<ComPtr<IDWriteFontFace5>> = (*self.native.get()).query_interface(&IDWriteFontFace5::uuidof()); |
| &self, | ||
| simulations: DWRITE_FONT_SIMULATIONS, | ||
| axis_values: &[DWRITE_FONT_AXIS_VALUE], | ||
| ) -> Option<FontFace> { |
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can we have some sort of an error code here (and return Result)?
src/font_face.rs
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| axis_values: &[DWRITE_FONT_AXIS_VALUE], | ||
| ) -> Option<FontFace> { | ||
| unsafe { | ||
| let face5: Option<ComPtr<IDWriteFontFace5>> = (*self.native.get()).query_interface(&IDWriteFontFace5::uuidof()); |
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is this how extension methods are discovered in dwrote? I wonder if the query_interface would be better to call at the construction site and just cache this ComPtr<IDWriteFontFace5> somewhere.
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I added support for caching the FontFace5 on demand - I don't want to impose the cost of querying it on all fonts, just the ones that need it for variations. As for errors, the errors are mostly dealt with ahead of time in Gecko, and we just need a pass or fail here with Option being what is most consistent with dwrote. This is a niche case where I do not believe having to construct a new error type just for it would add any value, since it would require decoding HRESULTs and other nastiness. And I don't know there's anything we can do with the HRESULT either. |
Is it really going to show up in any profiles though? I imagine we do hundreds of COM calls on a font, so querying the interface at load time shouldn't be a concern. |
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It mirrors the way we deal with it in Gecko. There's no need to incur the
expense when for 99% of fonts it is not needed at all.
…On Fri, Sep 21, 2018 at 4:36 PM Dzmitry Malyshau ***@***.***> wrote:
I don't want to impose the cost of querying it on all fonts, just the ones
that need it for variations.
Is it really going to show up in any profiles though? I imagine we do
hundreds of COM calls on a font, so querying the interface at load time
shouldn't be a concern.
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hmm, doesn't look like there are permanent reviewers |
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📌 Commit 8dbd988 has been approved by |
add support for creating variation fonts This is necessary to fix downstream Gecko bug https://bugzilla.mozilla.org/show_bug.cgi?id=1441323
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☀️ Test successful - status-appveyor |
This is necessary to fix downstream Gecko bug https://bugzilla.mozilla.org/show_bug.cgi?id=1441323