Implement vectorial text support for `iced_wgpu`

1 files changed, 188 insertions, 37 deletions

diff --git a/wgpu/src/geometry.rs b/wgpu/src/geometry.rs
index 04718441..a1583a07 100644
--- a/wgpu/src/geometry.rs
+++ b/wgpu/src/geometry.rs
@@ -1,6 +1,7 @@
 //! Build and draw geometry.
+use crate::core::alignment;
 use crate::core::text::LineHeight;
-use crate::core::{Pixels, Point, Rectangle, Size, Vector};
+use crate::core::{Color, Pixels, Point, Rectangle, Size, Vector};
 use crate::graphics::color;
 use crate::graphics::geometry::fill::{self, Fill};
 use crate::graphics::geometry::{
@@ -8,6 +9,7 @@ use crate::graphics::geometry::{
 };
 use crate::graphics::gradient::{self, Gradient};
 use crate::graphics::mesh::{self, Mesh};
+use crate::graphics::text::{self, cosmic_text};
 use crate::primitive::{self, Primitive};
 
 use lyon::geom::euclid;
@@ -123,8 +125,13 @@ impl Transform {
         self.0 == lyon::math::Transform::identity()
     }
 
+    fn is_scale_translation(&self) -> bool {
+        self.0.m12.abs() < 2.0 * f32::EPSILON
+            && self.0.m21.abs() < 2.0 * f32::EPSILON
+    }
+
     fn scale(&self) -> (f32, f32) {
-        (self.0.m12, self.0.m22)
+        (self.0.m11, self.0.m22)
     }
 
     fn transform_point(&self, point: Point) -> Point {
@@ -324,49 +331,193 @@ impl Frame {
     pub fn fill_text(&mut self, text: impl Into<Text>) {
         let text = text.into();
 
-        let (position, size, line_height) =
-            if self.transforms.current.is_identity() {
-                (text.position, text.size, text.line_height)
-            } else {
-                let (_, scale_y) = self.transforms.current.scale();
+        let (scale_x, scale_y) = self.transforms.current.scale();
+
+        if self.transforms.current.is_scale_translation()
+            && scale_x == scale_y
+            && scale_x > 0.0
+            && scale_y > 0.0
+        {
+            let (position, size, line_height) =
+                if self.transforms.current.is_identity() {
+                    (text.position, text.size, text.line_height)
+                } else {
+                    let position =
+                        self.transforms.current.transform_point(text.position);
+
+                    let size = Pixels(text.size.0 * scale_y);
+
+                    let line_height = match text.line_height {
+                        LineHeight::Absolute(size) => {
+                            LineHeight::Absolute(Pixels(size.0 * scale_y))
+                        }
+                        LineHeight::Relative(factor) => {
+                            LineHeight::Relative(factor)
+                        }
+                    };
+
+                    (position, size, line_height)
+                };
 
-                let position =
-                    self.transforms.current.transform_point(text.position);
+            let bounds = Rectangle {
+                x: position.x,
+                y: position.y,
+                width: f32::INFINITY,
+                height: f32::INFINITY,
+            };
 
-                let size = Pixels(text.size.0 * scale_y);
+            // TODO: Honor layering!
+            self.primitives.push(Primitive::Text {
+                content: text.content,
+                bounds,
+                color: text.color,
+                size,
+                line_height,
+                font: text.font,
+                horizontal_alignment: text.horizontal_alignment,
+                vertical_alignment: text.vertical_alignment,
+                shaping: text.shaping,
+                clip_bounds: Rectangle::with_size(Size::INFINITY),
+            });
+        } else {
+            let mut font_system =
+                text::font_system().write().expect("Write font system");
 
-                let line_height = match text.line_height {
-                    LineHeight::Absolute(size) => {
-                        LineHeight::Absolute(Pixels(size.0 * scale_y))
-                    }
-                    LineHeight::Relative(factor) => {
-                        LineHeight::Relative(factor)
+            let mut buffer = cosmic_text::BufferLine::new(
+                &text.content,
+                cosmic_text::AttrsList::new(text::to_attributes(text.font)),
+                text::to_shaping(text.shaping),
+            );
+
+            let layout = buffer.layout(
+                font_system.raw(),
+                text.size.0,
+                f32::MAX,
+                cosmic_text::Wrap::None,
+            );
+
+            let translation_x = match text.horizontal_alignment {
+                alignment::Horizontal::Left => text.position.x,
+                alignment::Horizontal::Center
+                | alignment::Horizontal::Right => {
+                    let mut line_width = 0.0f32;
+
+                    for line in layout.iter() {
+                        line_width = line_width.max(line.w);
                     }
-                };
 
-                (position, size, line_height)
+                    if text.horizontal_alignment
+                        == alignment::Horizontal::Center
+                    {
+                        text.position.x - line_width / 2.0
+                    } else {
+                        text.position.x - line_width
+                    }
+                }
             };
 
-        let bounds = Rectangle {
-            x: position.x,
-            y: position.y,
-            width: f32::INFINITY,
-            height: f32::INFINITY,
-        };
+            let translation_y = {
+                let line_height = text.line_height.to_absolute(text.size);
 
-        // TODO: Use vectorial text instead of primitive
-        self.primitives.push(Primitive::Text {
-            content: text.content,
-            bounds,
-            color: text.color,
-            size,
-            line_height,
-            font: text.font,
-            horizontal_alignment: text.horizontal_alignment,
-            vertical_alignment: text.vertical_alignment,
-            shaping: text.shaping,
-            clip_bounds: Rectangle::with_size(Size::INFINITY),
-        });
+                match text.vertical_alignment {
+                    alignment::Vertical::Top => text.position.y,
+                    alignment::Vertical::Center => {
+                        text.position.y - line_height.0 / 2.0
+                    }
+                    alignment::Vertical::Bottom => {
+                        text.position.y - line_height.0
+                    }
+                }
+            };
+
+            let mut swash_cache = cosmic_text::SwashCache::new();
+
+            for run in layout.iter() {
+                for glyph in run.glyphs.iter() {
+                    let physical_glyph = glyph.physical((0.0, 0.0), 1.0);
+
+                    let start_x = translation_x + glyph.x + glyph.x_offset;
+                    let start_y = translation_y + glyph.y_offset + text.size.0;
+                    let offset = Vector::new(start_x, start_y);
+
+                    if let Some(commands) = swash_cache.get_outline_commands(
+                        font_system.raw(),
+                        physical_glyph.cache_key,
+                    ) {
+                        let glyph = Path::new(|path| {
+                            use cosmic_text::Command;
+
+                            for command in commands {
+                                match command {
+                                    Command::MoveTo(p) => {
+                                        path.move_to(
+                                            Point::new(p.x, -p.y) + offset,
+                                        );
+                                    }
+                                    Command::LineTo(p) => {
+                                        path.line_to(
+                                            Point::new(p.x, -p.y) + offset,
+                                        );
+                                    }
+                                    Command::CurveTo(
+                                        control_a,
+                                        control_b,
+                                        to,
+                                    ) => {
+                                        path.bezier_curve_to(
+                                            Point::new(
+                                                control_a.x,
+                                                -control_a.y,
+                                            ) + offset,
+                                            Point::new(
+                                                control_b.x,
+                                                -control_b.y,
+                                            ) + offset,
+                                            Point::new(to.x, -to.y) + offset,
+                                        );
+                                    }
+                                    Command::QuadTo(control, to) => {
+                                        path.quadratic_curve_to(
+                                            Point::new(control.x, -control.y)
+                                                + offset,
+                                            Point::new(to.x, -to.y) + offset,
+                                        );
+                                    }
+                                    Command::Close => {
+                                        path.close();
+                                    }
+                                }
+                            }
+                        });
+
+                        self.fill(&glyph, text.color);
+                    } else {
+                        // TODO: Raster image support for `Canvas`
+                        let [r, g, b, a] = text.color.into_rgba8();
+
+                        swash_cache.with_pixels(
+                            font_system.raw(),
+                            physical_glyph.cache_key,
+                            cosmic_text::Color::rgba(r, g, b, a),
+                            |x, y, color| {
+                                self.fill(
+                                    &Path::rectangle(
+                                        Point::new(x as f32, y as f32) + offset,
+                                        Size::new(1.0, 1.0),
+                                    ),
+                                    Color::from_rgba8(
+                                        color.r(),
+                                        color.g(),
+                                        color.b(),
+                                        color.a() as f32 / 255.0,
+                                    ),
+                                );
+                            },
+                        )
+                    }
+                }
+            }
+        }
     }
 
     /// Stores the current transform of the [`Frame`] and executes the given