Render COLR Glyphs (Emoji) (#615)

This is following the breadcrumbs laid out in [#gpu > Emoji Rendering](https://xi.zulipchat.com/#narrow/stream/197075-gpu/topic/Emoji.20rendering) This supports rendering COLR emoji; we assume that these are reasonably well behaved. ![image](https://github.com/linebender/vello/assets/36049421/42c11e1d-ef64-4f4e-bd61-9ee6c09c223c) For examples, we use a very small subset of [Noto Color Emoji](https://fonts.google.com/noto/specimen/Noto+Color+Emoji), which is approximately 5.5kB. Fixes #536 We will need a follow up issue for `sbix`/`CBDT`. I presume we're ignoring svg-in-opentype. --------- Co-authored-by: Chad Brokaw <[email protected]>
linebender · Jun 21, 2024 · 886604b · 886604b
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diff --git a/examples/assets/noto_color_emoji/LICENSE.txt b/examples/assets/noto_color_emoji/LICENSE.txt
@@ -0,0 +1,93 @@
+Copyright 2021 Google Inc. All Rights Reserved.
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://openfontlicense.org
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
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+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
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+"Original Version" refers to the collection of Font Software components as
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+"Modified Version" refers to any derivative made by adding to, deleting,
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+Original Version, by changing formats or by porting the Font Software to a
+new environment.
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+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
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+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
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+Software, subject to the following conditions:
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+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
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+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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diff --git a/examples/assets/noto_color_emoji/NotoColorEmoji-Subset.ttf b/examples/assets/noto_color_emoji/NotoColorEmoji-Subset.ttf
diff --git a/examples/assets/noto_color_emoji/README.md b/examples/assets/noto_color_emoji/README.md
@@ -0,0 +1,11 @@
+# Noto Color Emoji Subset
+
+This folder contains a small subset of [Noto Color Emoji](https://fonts.google.com/noto/specimen/Noto+Color+Emoji), licensed under the [OFL version 1.1](LICENSE).
+We do not include the full set of Emoji, because including the entire Emoji set would increase the repository size too much.
+Note that Vello *does* support any COLR emoji (but not Emoji in other formats at the moment).
+Included emoji are:
+
+- ✅ Check Mark - \u{2705}/`:white_check_mark:`
+- 👀 Eyes - \u{1f440}/`:eyes:`
+- 🎉 Party Popper - \u{1f389}/`:party_popper:`
+- 🤠 Face with Cowboy Hat - \u{1f920}/`cowboy_hat_face`
diff --git a/examples/scenes/src/simple_text.rs b/examples/scenes/src/simple_text.rs
@@ -5,7 +5,7 @@ use std::sync::Arc;
 
 use vello::glyph::Glyph;
 use vello::kurbo::Affine;
-use vello::peniko::{Blob, Brush, BrushRef, Font, StyleRef};
+use vello::peniko::{Blob, Brush, BrushRef, Color, Font, StyleRef};
 use vello::skrifa::raw::FontRef;
 use vello::skrifa::MetadataProvider;
 use vello::Scene;
@@ -14,10 +14,13 @@ use vello::Scene;
 // On Windows, can set this to "c:\\Windows\\Fonts\\seguiemj.ttf" to get color emoji
 const ROBOTO_FONT: &[u8] = include_bytes!("../../assets/roboto/Roboto-Regular.ttf");
 const INCONSOLATA_FONT: &[u8] = include_bytes!("../../assets/inconsolata/Inconsolata.ttf");
+const NOTO_EMOJI_SUBSET: &[u8] =
+    include_bytes!("../../assets/noto_color_emoji/NotoColorEmoji-Subset.ttf");
 
 pub struct SimpleText {
     roboto: Font,
     inconsolata: Font,
+    noto_emoji_subset: Font,
 }
 
 impl SimpleText {
@@ -26,9 +29,43 @@ impl SimpleText {
         Self {
             roboto: Font::new(Blob::new(Arc::new(ROBOTO_FONT)), 0),
             inconsolata: Font::new(Blob::new(Arc::new(INCONSOLATA_FONT)), 0),
+            noto_emoji_subset: Font::new(Blob::new(Arc::new(NOTO_EMOJI_SUBSET)), 0),
         }
     }
 
+    /// Add a text run which supports some emoji.
+    ///
+    /// The supported Emoji are ✅, 👀, 🎉, and 🤠.
+    /// This subset is chosen to demonstrate the emoji support, whilst
+    /// not significantly increasing repository size.
+    ///
+    /// Note that Vello does support COLR emoji, but does not currently support
+    /// any other forms of emoji.
+    #[allow(clippy::too_many_arguments)]
+    pub fn add_emoji_run<'a>(
+        &mut self,
+        scene: &mut Scene,
+        size: f32,
+        transform: Affine,
+        glyph_transform: Option<Affine>,
+        style: impl Into<StyleRef<'a>>,
+        text: &str,
+    ) {
+        let font = self.noto_emoji_subset.clone();
+        self.add_var_run(
+            scene,
+            Some(&font),
+            size,
+            &[],
+            // This should be unused
+            &Brush::Solid(Color::WHITE),
+            transform,
+            glyph_transform,
+            style,
+            text,
+        );
+    }
+
     #[allow(clippy::too_many_arguments)]
     pub fn add_run<'a>(
         &mut self,

diff --git a/examples/scenes/src/test_scenes.rs b/examples/scenes/src/test_scenes.rs
@@ -46,6 +46,7 @@ pub fn test_scenes() -> SceneSet {
             "stroke_styles (skew)",
             false
         ),
+        scene!(emoji),
         scene!(tricky_strokes),
         scene!(fill_types),
         scene!(cardioid_and_friends),
@@ -70,6 +71,19 @@ pub fn test_scenes() -> SceneSet {
 
 // Scenes
 
+fn emoji(scene: &mut Scene, params: &mut SceneParams) {
+    let text_size = 120. + 20. * (params.time * 2.).sin() as f32;
+    let s = "🎉🤠✅";
+    params.text.add_emoji_run(
+        scene,
+        text_size,
+        Affine::translate(Vec2::new(100., 400.)),
+        None,
+        Fill::NonZero,
+        s,
+    );
+}
+
 fn funky_paths(scene: &mut Scene, _: &mut SceneParams) {
     use PathEl::*;
     let missing_movetos = [