Draft first working version of `iced_glow` :tada:

1 files changed, 180 insertions, 0 deletions

diff --git a/glow/src/text.rs b/glow/src/text.rs
new file mode 100644
index 00000000..bda619fc
--- /dev/null
+++ b/glow/src/text.rs
@@ -0,0 +1,180 @@
+mod font;
+
+use crate::Transformation;
+
+use std::{cell::RefCell, collections::HashMap};
+
+pub const BUILTIN_ICONS: iced_native::Font = iced_native::Font::External {
+    name: "iced_glow icons",
+    bytes: include_bytes!("text/icons.ttf"),
+};
+
+pub const CHECKMARK_ICON: char = '\u{F00C}';
+
+const FALLBACK_FONT: &[u8] =
+    include_bytes!("../../wgpu/fonts/Lato-Regular.ttf");
+
+#[derive(Debug)]
+pub struct Pipeline {
+    draw_brush: RefCell<glow_glyph::GlyphBrush<'static>>,
+    draw_font_map: RefCell<HashMap<String, glow_glyph::FontId>>,
+
+    measure_brush: RefCell<glyph_brush::GlyphBrush<'static, ()>>,
+}
+
+impl Pipeline {
+    pub fn new(gl: &glow::Context, default_font: Option<&[u8]>) -> Self {
+        // TODO: Font customization
+        let font_source = font::Source::new();
+
+        let default_font =
+            default_font.map(|slice| slice.to_vec()).unwrap_or_else(|| {
+                font_source
+                    .load(&[font::Family::SansSerif, font::Family::Serif])
+                    .unwrap_or_else(|_| FALLBACK_FONT.to_vec())
+            });
+
+        let load_glyph_brush = |font: Vec<u8>| {
+            let builder =
+                glow_glyph::GlyphBrushBuilder::using_fonts_bytes(vec![
+                    font.clone()
+                ])?;
+
+            Ok((
+                builder,
+                glyph_brush::GlyphBrushBuilder::using_font_bytes(font).build(),
+            ))
+        };
+
+        let (brush_builder, measure_brush) = load_glyph_brush(default_font)
+            .unwrap_or_else(|_: glow_glyph::rusttype::Error| {
+                log::warn!("System font failed to load. Falling back to embedded font...");
+
+                load_glyph_brush(FALLBACK_FONT.to_vec()).expect("Load fallback font")
+            });
+
+        let draw_brush =
+            brush_builder.initial_cache_size((2048, 2048)).build(gl);
+
+        Pipeline {
+            draw_brush: RefCell::new(draw_brush),
+            draw_font_map: RefCell::new(HashMap::new()),
+
+            measure_brush: RefCell::new(measure_brush),
+        }
+    }
+
+    pub fn overlay_font(&self) -> glow_glyph::FontId {
+        glow_glyph::FontId(0)
+    }
+
+    pub fn queue(&mut self, section: glow_glyph::Section<'_>) {
+        self.draw_brush.borrow_mut().queue(section);
+    }
+
+    pub fn draw_queued(
+        &mut self,
+        gl: &glow::Context,
+        transformation: Transformation,
+        region: glow_glyph::Region,
+    ) {
+        self.draw_brush
+            .borrow_mut()
+            .draw_queued_with_transform_and_scissoring(
+                gl,
+                transformation.into(),
+                region,
+            )
+            .expect("Draw text");
+    }
+
+    pub fn measure(
+        &self,
+        content: &str,
+        size: f32,
+        font: iced_native::Font,
+        bounds: iced_native::Size,
+    ) -> (f32, f32) {
+        use glow_glyph::GlyphCruncher;
+
+        let glow_glyph::FontId(font_id) = self.find_font(font);
+
+        let section = glow_glyph::Section {
+            text: content,
+            scale: glow_glyph::Scale { x: size, y: size },
+            bounds: (bounds.width, bounds.height),
+            font_id: glow_glyph::FontId(font_id),
+            ..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)
+        }
+    }
+
+    pub fn space_width(&self, size: f32) -> f32 {
+        use glow_glyph::GlyphCruncher;
+
+        let glyph_brush = self.measure_brush.borrow();
+
+        // TODO: Select appropriate font
+        let font = &glyph_brush.fonts()[0];
+
+        font.glyph(' ')
+            .scaled(glow_glyph::Scale { x: size, y: size })
+            .h_metrics()
+            .advance_width
+    }
+
+    pub fn clear_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);
+                }
+            }
+        }
+    }
+
+    pub fn find_font(&self, font: iced_native::Font) -> glow_glyph::FontId {
+        match font {
+            iced_native::Font::Default => glow_glyph::FontId(0),
+            iced_native::Font::External { name, bytes } => {
+                if let Some(font_id) = self.draw_font_map.borrow().get(name) {
+                    return *font_id;
+                }
+
+                // TODO: Find a way to share font data
+                let _ = self.measure_brush.borrow_mut().add_font_bytes(bytes);
+
+                let font_id =
+                    self.draw_brush.borrow_mut().add_font_bytes(bytes);
+
+                let _ = self
+                    .draw_font_map
+                    .borrow_mut()
+                    .insert(String::from(name), font_id);
+
+                font_id
+            }
+        }
+    }
+}