Merge pull request #1697 from iced-rs/text-glyphon

Text shaping, font fallback, and `iced_wgpu` overhaul

1 files changed, 362 insertions, 209 deletions

diff --git a/wgpu/src/text.rs b/wgpu/src/text.rs
index e17b84c1..dea6ab18 100644
--- a/wgpu/src/text.rs
+++ b/wgpu/src/text.rs
@@ -1,128 +1,267 @@
-use crate::Transformation;
-
-use iced_graphics::font;
+pub use iced_native::text::Hit;
 
-use std::{cell::RefCell, collections::HashMap};
-use wgpu_glyph::ab_glyph;
+use iced_graphics::layer::Text;
+use iced_native::alignment;
+use iced_native::{Color, Font, Rectangle, Size};
 
-pub use iced_native::text::Hit;
+use rustc_hash::{FxHashMap, FxHashSet};
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::collections::hash_map;
+use std::hash::{BuildHasher, Hash, Hasher};
+use std::sync::Arc;
 
-#[derive(Debug)]
+#[allow(missing_debug_implementations)]
 pub struct Pipeline {
-    draw_brush: RefCell<wgpu_glyph::GlyphBrush<()>>,
-    draw_font_map: RefCell<HashMap<String, wgpu_glyph::FontId>>,
-    measure_brush: RefCell<glyph_brush::GlyphBrush<()>>,
+    system: Option<System>,
+    renderers: Vec<glyphon::TextRenderer>,
+    atlas: glyphon::TextAtlas,
+    prepare_layer: usize,
+}
+
+#[ouroboros::self_referencing]
+struct System {
+    fonts: glyphon::FontSystem,
+
+    #[borrows(fonts)]
+    #[not_covariant]
+    measurement_cache: RefCell<Cache<'this>>,
+
+    #[borrows(fonts)]
+    #[not_covariant]
+    render_cache: Cache<'this>,
 }
 
 impl Pipeline {
     pub fn new(
         device: &wgpu::Device,
+        queue: &wgpu::Queue,
         format: wgpu::TextureFormat,
-        default_font: Option<&[u8]>,
-        multithreading: bool,
     ) -> Self {
-        let default_font = default_font.map(|slice| slice.to_vec());
-
-        // TODO: Font customization
-        #[cfg(not(target_os = "ios"))]
-        #[cfg(feature = "default_system_font")]
-        let default_font = {
-            default_font.or_else(|| {
-                font::Source::new()
-                    .load(&[font::Family::SansSerif, font::Family::Serif])
-                    .ok()
-            })
-        };
+        Pipeline {
+            system: Some(
+                SystemBuilder {
+                    fonts: glyphon::FontSystem::new_with_fonts(
+                        [glyphon::fontdb::Source::Binary(Arc::new(
+                            include_bytes!("../fonts/Iced-Icons.ttf")
+                                .as_slice(),
+                        ))]
+                        .into_iter(),
+                    ),
+                    measurement_cache_builder: |_| RefCell::new(Cache::new()),
+                    render_cache_builder: |_| Cache::new(),
+                }
+                .build(),
+            ),
+            renderers: Vec::new(),
+            atlas: glyphon::TextAtlas::new(device, queue, format),
+            prepare_layer: 0,
+        }
+    }
 
-        let default_font =
-            default_font.unwrap_or_else(|| font::FALLBACK.to_vec());
+    pub fn load_font(&mut self, bytes: Cow<'static, [u8]>) {
+        let heads = self.system.take().unwrap().into_heads();
 
-        let font = ab_glyph::FontArc::try_from_vec(default_font)
-            .unwrap_or_else(|_| {
-                log::warn!(
-                    "System font failed to load. Falling back to \
-                    embedded font..."
-                );
+        let (locale, mut db) = heads.fonts.into_locale_and_db();
 
-                ab_glyph::FontArc::try_from_slice(font::FALLBACK)
-                    .expect("Load fallback font")
-            });
+        db.load_font_source(glyphon::fontdb::Source::Binary(Arc::new(
+            bytes.into_owned(),
+        )));
+
+        self.system = Some(
+            SystemBuilder {
+                fonts: glyphon::FontSystem::new_with_locale_and_db(locale, db),
+                measurement_cache_builder: |_| RefCell::new(Cache::new()),
+                render_cache_builder: |_| Cache::new(),
+            }
+            .build(),
+        );
+    }
 
-        let draw_brush_builder =
-            wgpu_glyph::GlyphBrushBuilder::using_font(font.clone())
-                .initial_cache_size((2048, 2048))
-                .draw_cache_multithread(multithreading);
+    pub fn prepare(
+        &mut self,
+        device: &wgpu::Device,
+        queue: &wgpu::Queue,
+        sections: &[Text<'_>],
+        bounds: Rectangle,
+        scale_factor: f32,
+        target_size: Size<u32>,
+    ) -> bool {
+        self.system.as_mut().unwrap().with_mut(|fields| {
+            if self.renderers.len() <= self.prepare_layer {
+                self.renderers
+                    .push(glyphon::TextRenderer::new(device, queue));
+            }
 
-        #[cfg(target_arch = "wasm32")]
-        let draw_brush_builder = draw_brush_builder.draw_cache_align_4x4(true);
+            let renderer = &mut self.renderers[self.prepare_layer];
+
+            let keys: Vec<_> = sections
+                .iter()
+                .map(|section| {
+                    let (key, _) = fields.render_cache.allocate(
+                        fields.fonts,
+                        Key {
+                            content: section.content,
+                            size: section.size * scale_factor,
+                            font: section.font,
+                            bounds: Size {
+                                width: (section.bounds.width * scale_factor)
+                                    .ceil(),
+                                height: (section.bounds.height * scale_factor)
+                                    .ceil(),
+                            },
+                            color: section.color,
+                        },
+                    );
+
+                    key
+                })
+                .collect();
+
+            let bounds = glyphon::TextBounds {
+                left: (bounds.x * scale_factor) as i32,
+                top: (bounds.y * scale_factor) as i32,
+                right: ((bounds.x + bounds.width) * scale_factor) as i32,
+                bottom: ((bounds.y + bounds.height) * scale_factor) as i32,
+            };
+
+            let text_areas =
+                sections.iter().zip(keys.iter()).map(|(section, key)| {
+                    let buffer = fields
+                        .render_cache
+                        .get(key)
+                        .expect("Get cached buffer");
+
+                    let x = section.bounds.x * scale_factor;
+                    let y = section.bounds.y * scale_factor;
+
+                    let (total_lines, max_width) = buffer
+                        .layout_runs()
+                        .enumerate()
+                        .fold((0, 0.0), |(_, max), (i, buffer)| {
+                            (i + 1, buffer.line_w.max(max))
+                        });
+
+                    let total_height =
+                        total_lines as f32 * section.size * 1.2 * scale_factor;
+
+                    let left = match section.horizontal_alignment {
+                        alignment::Horizontal::Left => x,
+                        alignment::Horizontal::Center => x - max_width / 2.0,
+                        alignment::Horizontal::Right => x - max_width,
+                    };
+
+                    let top = match section.vertical_alignment {
+                        alignment::Vertical::Top => y,
+                        alignment::Vertical::Center => y - total_height / 2.0,
+                        alignment::Vertical::Bottom => y - total_height,
+                    };
+
+                    glyphon::TextArea {
+                        buffer,
+                        left: left as i32,
+                        top: top as i32,
+                        bounds,
+                    }
+                });
+
+            let result = renderer.prepare(
+                device,
+                queue,
+                &mut self.atlas,
+                glyphon::Resolution {
+                    width: target_size.width,
+                    height: target_size.height,
+                },
+                text_areas,
+                glyphon::Color::rgb(0, 0, 0),
+                &mut glyphon::SwashCache::new(fields.fonts),
+            );
+
+            match result {
+                Ok(()) => {
+                    self.prepare_layer += 1;
+
+                    true
+                }
+                Err(glyphon::PrepareError::AtlasFull(content_type)) => {
+                    self.prepare_layer = 0;
+
+                    #[allow(clippy::needless_bool)]
+                    if self.atlas.grow(device, content_type) {
+                        false
+                    } else {
+                        // If the atlas cannot grow, then all bets are off.
+                        // Instead of panicking, we will just pray that the result
+                        // will be somewhat readable...
+                        true
+                    }
+                }
+            }
+        })
+    }
 
-        let draw_brush = draw_brush_builder.build(device, format);
+    pub fn render<'a>(
+        &'a self,
+        layer: usize,
+        bounds: Rectangle<u32>,
+        render_pass: &mut wgpu::RenderPass<'a>,
+    ) {
+        let renderer = &self.renderers[layer];
 
-        let measure_brush =
-            glyph_brush::GlyphBrushBuilder::using_font(font).build();
+        render_pass.set_scissor_rect(
+            bounds.x,
+            bounds.y,
+            bounds.width,
+            bounds.height,
+        );
 
-        Pipeline {
-            draw_brush: RefCell::new(draw_brush),
-            draw_font_map: RefCell::new(HashMap::new()),
-            measure_brush: RefCell::new(measure_brush),
-        }
+        renderer
+            .render(&self.atlas, render_pass)
+            .expect("Render text");
     }
 
-    pub fn queue(&mut self, section: wgpu_glyph::Section<'_>) {
-        self.draw_brush.borrow_mut().queue(section);
-    }
+    pub fn end_frame(&mut self) {
+        self.atlas.trim();
 
-    pub fn draw_queued(
-        &mut self,
-        device: &wgpu::Device,
-        staging_belt: &mut wgpu::util::StagingBelt,
-        encoder: &mut wgpu::CommandEncoder,
-        target: &wgpu::TextureView,
-        transformation: Transformation,
-        region: wgpu_glyph::Region,
-    ) {
-        self.draw_brush
-            .borrow_mut()
-            .draw_queued_with_transform_and_scissoring(
-                device,
-                staging_belt,
-                encoder,
-                target,
-                transformation.into(),
-                region,
-            )
-            .expect("Draw text");
+        self.system
+            .as_mut()
+            .unwrap()
+            .with_render_cache_mut(|cache| cache.trim());
+
+        self.prepare_layer = 0;
     }
 
     pub fn measure(
         &self,
         content: &str,
         size: f32,
-        font: iced_native::Font,
-        bounds: iced_native::Size,
+        font: Font,
+        bounds: Size,
     ) -> (f32, f32) {
-        use wgpu_glyph::GlyphCruncher;
-
-        let wgpu_glyph::FontId(font_id) = self.find_font(font);
-
-        let section = wgpu_glyph::Section {
-            bounds: (bounds.width, bounds.height),
-            text: vec![wgpu_glyph::Text {
-                text: content,
-                scale: size.into(),
-                font_id: wgpu_glyph::FontId(font_id),
-                extra: wgpu_glyph::Extra::default(),
-            }],
-            ..Default::default()
-        };
-
-        if let Some(bounds) =
-            self.measure_brush.borrow_mut().glyph_bounds(section)
-        {
-            (bounds.width().ceil(), bounds.height().ceil())
-        } else {
-            (0.0, 0.0)
-        }
+        self.system.as_ref().unwrap().with(|fields| {
+            let mut measurement_cache = fields.measurement_cache.borrow_mut();
+
+            let (_, paragraph) = measurement_cache.allocate(
+                fields.fonts,
+                Key {
+                    content,
+                    size,
+                    font,
+                    bounds,
+                    color: Color::BLACK,
+                },
+            );
+
+            let (total_lines, max_width) = paragraph
+                .layout_runs()
+                .enumerate()
+                .fold((0, 0.0), |(_, max), (i, buffer)| {
+                    (i + 1, buffer.line_w.max(max))
+                });
+
+            (max_width, size * 1.2 * total_lines as f32)
+        })
     }
 
     pub fn hit_test(
@@ -132,134 +271,148 @@ impl Pipeline {
         font: iced_native::Font,
         bounds: iced_native::Size,
         point: iced_native::Point,
-        nearest_only: bool,
+        _nearest_only: bool,
     ) -> Option<Hit> {
-        use wgpu_glyph::GlyphCruncher;
-
-        let wgpu_glyph::FontId(font_id) = self.find_font(font);
-
-        let section = wgpu_glyph::Section {
-            bounds: (bounds.width, bounds.height),
-            text: vec![wgpu_glyph::Text {
-                text: content,
-                scale: size.into(),
-                font_id: wgpu_glyph::FontId(font_id),
-                extra: wgpu_glyph::Extra::default(),
-            }],
-            ..Default::default()
-        };
+        self.system.as_ref().unwrap().with(|fields| {
+            let mut measurement_cache = fields.measurement_cache.borrow_mut();
+
+            let (_, paragraph) = measurement_cache.allocate(
+                fields.fonts,
+                Key {
+                    content,
+                    size,
+                    font,
+                    bounds,
+                    color: Color::BLACK,
+                },
+            );
+
+            let cursor = paragraph.hit(point.x, point.y)?;
+
+            Some(Hit::CharOffset(cursor.index))
+        })
+    }
 
-        let mut mb = self.measure_brush.borrow_mut();
-
-        // The underlying type is FontArc, so clones are cheap.
-        use wgpu_glyph::ab_glyph::{Font, ScaleFont};
-        let font = mb.fonts()[font_id].clone().into_scaled(size);
-
-        // Implements an iterator over the glyph bounding boxes.
-        let bounds = mb.glyphs(section).map(
-            |wgpu_glyph::SectionGlyph {
-                 byte_index, glyph, ..
-             }| {
-                (
-                    *byte_index,
-                    iced_native::Rectangle::new(
-                        iced_native::Point::new(
-                            glyph.position.x - font.h_side_bearing(glyph.id),
-                            glyph.position.y - font.ascent(),
-                        ),
-                        iced_native::Size::new(
-                            font.h_advance(glyph.id),
-                            font.ascent() - font.descent(),
-                        ),
-                    ),
-                )
-            },
-        );
+    pub fn trim_measurement_cache(&mut self) {
+        self.system
+            .as_mut()
+            .unwrap()
+            .with_measurement_cache_mut(|cache| cache.borrow_mut().trim());
+    }
+}
 
-        // Implements computation of the character index based on the byte index
-        // within the input string.
-        let char_index = |byte_index| {
-            let mut b_count = 0;
-            for (i, utf8_len) in
-                content.chars().map(|c| c.len_utf8()).enumerate()
-            {
-                if byte_index < (b_count + utf8_len) {
-                    return i;
-                }
-                b_count += utf8_len;
-            }
+fn to_family(font: Font) -> glyphon::Family<'static> {
+    match font {
+        Font::Name(name) => glyphon::Family::Name(name),
+        Font::SansSerif => glyphon::Family::SansSerif,
+        Font::Serif => glyphon::Family::Serif,
+        Font::Cursive => glyphon::Family::Cursive,
+        Font::Fantasy => glyphon::Family::Fantasy,
+        Font::Monospace => glyphon::Family::Monospace,
+    }
+}
 
-            byte_index
-        };
+struct Cache<'a> {
+    entries: FxHashMap<KeyHash, glyphon::Buffer<'a>>,
+    recently_used: FxHashSet<KeyHash>,
+    hasher: HashBuilder,
+    trim_count: usize,
+}
 
-        if !nearest_only {
-            for (idx, bounds) in bounds.clone() {
-                if bounds.contains(point) {
-                    return Some(Hit::CharOffset(char_index(idx)));
-                }
-            }
-        }
+#[cfg(not(target_arch = "wasm32"))]
+type HashBuilder = twox_hash::RandomXxHashBuilder64;
 
-        let nearest = bounds
-            .map(|(index, bounds)| (index, bounds.center()))
-            .min_by(|(_, center_a), (_, center_b)| {
-                center_a
-                    .distance(point)
-                    .partial_cmp(&center_b.distance(point))
-                    .unwrap_or(std::cmp::Ordering::Greater)
-            });
-
-        nearest.map(|(idx, center)| {
-            Hit::NearestCharOffset(char_index(idx), point - center)
-        })
-    }
+#[cfg(target_arch = "wasm32")]
+type HashBuilder = std::hash::BuildHasherDefault<twox_hash::XxHash64>;
 
-    pub fn trim_measurement_cache(&mut self) {
-        // TODO: We should probably use a `GlyphCalculator` for this. However,
-        // it uses a lifetimed `GlyphCalculatorGuard` with side-effects on drop.
-        // This makes stuff quite inconvenient. A manual method for trimming the
-        // cache would make our lives easier.
-        loop {
-            let action = self
-                .measure_brush
-                .borrow_mut()
-                .process_queued(|_, _| {}, |_| {});
-
-            match action {
-                Ok(_) => break,
-                Err(glyph_brush::BrushError::TextureTooSmall { suggested }) => {
-                    let (width, height) = suggested;
-
-                    self.measure_brush
-                        .borrow_mut()
-                        .resize_texture(width, height);
-                }
-            }
+impl<'a> Cache<'a> {
+    const TRIM_INTERVAL: usize = 300;
+
+    fn new() -> Self {
+        Self {
+            entries: FxHashMap::default(),
+            recently_used: FxHashSet::default(),
+            hasher: HashBuilder::default(),
+            trim_count: 0,
         }
     }
 
-    pub fn find_font(&self, font: iced_native::Font) -> wgpu_glyph::FontId {
-        match font {
-            iced_native::Font::Default => wgpu_glyph::FontId(0),
-            iced_native::Font::External { name, bytes } => {
-                if let Some(font_id) = self.draw_font_map.borrow().get(name) {
-                    return *font_id;
-                }
+    fn get(&self, key: &KeyHash) -> Option<&glyphon::Buffer<'a>> {
+        self.entries.get(key)
+    }
 
-                let font = ab_glyph::FontArc::try_from_slice(bytes)
-                    .expect("Load font");
+    fn allocate(
+        &mut self,
+        fonts: &'a glyphon::FontSystem,
+        key: Key<'_>,
+    ) -> (KeyHash, &mut glyphon::Buffer<'a>) {
+        let hash = {
+            let mut hasher = self.hasher.build_hasher();
+
+            key.content.hash(&mut hasher);
+            key.size.to_bits().hash(&mut hasher);
+            key.font.hash(&mut hasher);
+            key.bounds.width.to_bits().hash(&mut hasher);
+            key.bounds.height.to_bits().hash(&mut hasher);
+            key.color.into_rgba8().hash(&mut hasher);
+
+            hasher.finish()
+        };
 
-                let _ = self.measure_brush.borrow_mut().add_font(font.clone());
+        if let hash_map::Entry::Vacant(entry) = self.entries.entry(hash) {
+            let metrics = glyphon::Metrics::new(key.size, key.size * 1.2);
+            let mut buffer = glyphon::Buffer::new(fonts, metrics);
+
+            buffer.set_size(
+                key.bounds.width,
+                key.bounds.height.max(key.size * 1.2),
+            );
+            buffer.set_text(
+                key.content,
+                glyphon::Attrs::new()
+                    .family(to_family(key.font))
+                    .color({
+                        let [r, g, b, a] = key.color.into_linear();
+
+                        glyphon::Color::rgba(
+                            (r * 255.0) as u8,
+                            (g * 255.0) as u8,
+                            (b * 255.0) as u8,
+                            (a * 255.0) as u8,
+                        )
+                    })
+                    .monospaced(matches!(key.font, Font::Monospace)),
+            );
+
+            let _ = entry.insert(buffer);
+        }
 
-                let font_id = self.draw_brush.borrow_mut().add_font(font);
+        let _ = self.recently_used.insert(hash);
 
-                let _ = self
-                    .draw_font_map
-                    .borrow_mut()
-                    .insert(String::from(name), font_id);
+        (hash, self.entries.get_mut(&hash).unwrap())
+    }
 
-                font_id
-            }
+    fn trim(&mut self) {
+        if self.trim_count >= Self::TRIM_INTERVAL {
+            self.entries
+                .retain(|key, _| self.recently_used.contains(key));
+
+            self.recently_used.clear();
+
+            self.trim_count = 0;
+        } else {
+            self.trim_count += 1;
         }
     }
 }
+
+#[derive(Debug, Clone, Copy)]
+struct Key<'a> {
+    content: &'a str,
+    size: f32,
+    font: Font,
+    bounds: Size,
+    color: Color,
+}
+
+type KeyHash = u64;