DirectWrite font rendering for Windows #549

vvuk · 2016-11-09T21:41:18Z

This PR adds DirectWrite font rendering for Windows, using a thin native-rust dwrite wrapper library. There's a corresponding PR for Servo that adds support for DirectWrite to their font backend as well.

Things work, though right now there is no support for web fonts. This isn't hard to add and should be straightforward; @metajack already has rust code for implementing the required COM interfaces to do so, and this just needs to be done in https://github.com/vvuk/dwrote-rs.

This change is


        Update .gitignore

glennw

Nice! Just a few minor issues.

glennw · 2016-11-09T22:10:57Z

webrender/src/lib.rs

@@ -95,9 +101,12 @@ extern crate core_graphics;
 #[cfg(target_os="macos")]
 extern crate core_text;

-#[cfg(not(target_os="macos"))]
+#[cfg(any(target_os="linux", target_os="android"))]


This should be all(unix, not(target_os = "macos")) I think, since WR builds and runs on *BSD now.

glennw · 2016-11-09T22:10:57Z

webrender/src/platform/windows/font.rs

+use dwrote;
+
+pub struct FontContext {
+    // FIXME do I need to protect this in a mutex?


No - FontContexts are created per-thread and stored in TLS.

glennw · 2016-11-09T22:10:57Z

webrender/src/platform/windows/font.rs

+            return
+        }
+
+        panic!("DWrite can't do raw fonts yet");


Does this break a lot of websites? Should we consider making it non-fatal for now?

glennw · 2016-11-09T22:10:57Z

webrender_traits/src/types.rs

@@ -371,10 +372,13 @@ pub enum MixBlendMode {
 pub type NativeFontHandle = CGFont;

 /// Native fonts are not used on Linux; all fonts are raw.
-#[cfg(not(target_os = "macos"))]
-#[cfg_attr(not(target_os = "macos"), derive(Clone, Serialize, Deserialize))]
+#[cfg(any(target_os = "linux", target_os = "android"))]


Same here as the above comment about *BSD.

glennw · 2016-11-09T22:10:57Z

webrender/src/platform/windows/font.rs

+
+        // don't rasterize blank glyphs
+        if width_u == 0 || height_u == 0 {
+            return (Some(dims), Some(RasterizedGlyph {


WR expects the font platform to return None when the glyph has zero dimensions.


        Add DirectWrite backend to WebRender via dwrote

glennw · 2016-11-10T00:23:12Z

webrender_traits/src/types.rs

@@ -371,10 +372,13 @@ pub enum MixBlendMode {
 pub type NativeFontHandle = CGFont;

 /// Native fonts are not used on Linux; all fonts are raw.
-#[cfg(not(target_os = "macos"))]
-#[cfg_attr(not(target_os = "macos"), derive(Clone, Serialize, Deserialize))]
+#[cfg(all(unix, not(target_os="macos")))]


@vvuk This is resulting in Clone not being derived on Linux, causing a compile error. I'm not sure why - it looks correct to me. I guess we could try make it not(windows or mac) or something like that?

I don't understand what that change is supposed to do, but please do try not(windows or mac).

(@nox - @glennw left out a second added line which was the cfg_attr with the same conditional as the cfg)

Yeah, this is definitely a serde bug. In the generated types.rs, this is expanding out to:

#[cfg(target_os = "macos")] pub type NativeFontHandle = CGFont; #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)] #[cfg(all(unix, not(target_os = "macos")))] const _IMPL_DESERIALIZE_FOR_NativeFontHandle: () = ... #[cfg(target_os = "macos")] pub type NativeFontHandle = CGFont; #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)] #[cfg(all(unix, not(target_os = "macos")))] const _IMPL_DESERIALIZE_FOR_NativeFontHandle: () = { ... }; /// Native fonts are not used on Linux; all fonts are raw. #[cfg(all(unix, not(target_os = "macos")))] pub struct NativeFontHandle;

Note that all mention of derive(Clone) was lost. Even if I add a second cfg_attr with just derive(Clone) it gets eaten as well. Changing the conditional does not change the behaviour. Forcing serde to 0.8.16 doesn't help. Hrm.


        Change cfg/cfg_attr to working version


        Bump version to 0.8.1

vvuk · 2016-11-10T18:18:09Z

I pushed a new commit by itself that should fix this... hopefully someone from serde can look at it and see what's up with the other version.

glennw · 2016-11-10T19:12:35Z

@bors-servo r+

bors-servo · 2016-11-10T19:12:36Z

📌 Commit 2ace4b4 has been approved by glennw

bors-servo · 2016-11-10T19:12:39Z

⚡ Test exempted - status


        Auto merge of #549 - vvuk:dw-fonts, r=glennw

@metajack

DirectWrite font rendering for Windows This PR adds DirectWrite font rendering for Windows, using a thin native-rust dwrite wrapper library. There's a corresponding PR for Servo that adds support for DirectWrite to their font backend as well. Things work, though right now there is no support for web fonts. This isn't hard to add and should be straightforward; @metajack already has rust code for implementing the required COM interfaces to do so, and this just needs to be done in https://github.com/vvuk/dwrote-rs.  --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/webrender/549)

Update .gitignore

5949d2a

vvuk force-pushed the vvuk:dw-fonts branch from c8aadde to 64ea3ca Nov 9, 2016

glennw requested changes Nov 9, 2016

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Add DirectWrite backend to WebRender via dwrote

6a2f354

vvuk force-pushed the vvuk:dw-fonts branch from 64ea3ca to 09c4821 Nov 9, 2016

glennw approved these changes Nov 9, 2016

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glennw reviewed Nov 10, 2016

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vvuk added 2 commits Nov 10, 2016

Change cfg/cfg_attr to working version

efd4e1d

Bump version to 0.8.1

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2ace4b4

vvuk force-pushed the vvuk:dw-fonts branch from 09c4821 to 2ace4b4 Nov 10, 2016

bors-servo merged commit 2ace4b4 into servo:master Nov 10, 2016
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bors-servo mentioned this pull request Nov 10, 2016

Flatten the display list in the API #552

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vvuk mentioned this pull request Nov 11, 2016

serde_codegen seems to be removing derive()s with some cfg attrs serde-rs/serde#616

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vvuk deleted the vvuk:dw-fonts branch Dec 6, 2016

dtolnay mentioned this pull request Jan 7, 2017

Losing non-syntex derive behind cfg_attr serde-deprecated/syntex#110

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servo / webrender

DirectWrite font rendering for Windows #549

DirectWrite font rendering for Windows #549

vvuk commented Nov 9, 2016 •

edited by larsbergstrom

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vvuk commented Nov 10, 2016

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vvuk commented Nov 9, 2016 • edited by larsbergstrom

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vvuk commented Nov 10, 2016

glennw commented Nov 10, 2016

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vvuk commented Nov 9, 2016 •

edited by larsbergstrom