Add path drawing to software renderer

internal/core/Cargo.toml

@@ -19,8 +19,8 @@ categories = ["gui", "development-tools", "no-std"]
 path = "lib.rs"
 
 [features]
-ffi = ["dep:static_assertions"]           # Expose C ABI
-libm = ["num-traits/libm", "euclid/libm"]
+ffi = ["dep:static_assertions"]                         # Expose C ABI
+libm = ["num-traits/libm", "euclid/libm", "zeno?/libm"]
 # Allow the viewer to query at runtime information about item types
 rtti = []
 # Use the standard library
@@ -37,6 +37,7 @@ std = [
   "image-decoders",
   "svg",
   "raw-window-handle-06?/std",
+  "zeno?/std",
   "chrono/std",
   "chrono/wasmbind",
   "chrono/clock",
@@ -50,6 +51,7 @@ unsafe-single-threaded = []
 unicode = ["unicode-script", "unicode-linebreak"]
 
 software-renderer-systemfonts = ["shared-fontique", "skrifa", "fontdue", "software-renderer", "shared-parley"]
+software-renderer-path = ["dep:zeno"]
 software-renderer = ["bytemuck"]
 
 image-decoders = ["dep:image", "dep:clru"]
@@ -107,6 +109,7 @@ unicode-linebreak = { version = "0.1.5", optional = true }
 unicode-script = { version = "0.5.7", optional = true }
 integer-sqrt = { version = "0.1.5" }
 bytemuck = { workspace = true, optional = true, features = ["derive"] }
+zeno = { version = "0.3.3", optional = true, default-features = false, features = ["eval"] }
 sys-locale = { version = "0.3.2", optional = true }
 parley = { version = "0.6.0", optional = true }
 pulldown-cmark = { version = "0.13.0", optional = true }

internal/core/software_renderer.rs

@@ -11,6 +11,8 @@ mod draw_functions;
 mod fixed;
 mod fonts;
 mod minimal_software_window;
+#[cfg(feature = "software-renderer-path")]
+mod path;
 mod scene;
 
 use self::fonts::GlyphRenderer;
@@ -1301,6 +1303,23 @@ trait ProcessScene {
     fn process_linear_gradient(&mut self, geometry: PhysicalRect, gradient: LinearGradientCommand);
     fn process_radial_gradient(&mut self, geometry: PhysicalRect, gradient: RadialGradientCommand);
     fn process_conic_gradient(&mut self, geometry: PhysicalRect, gradient: ConicGradientCommand);
+    #[cfg(feature = "software-renderer-path")]
+    fn process_filled_path(
+        &mut self,
+        path_geometry: PhysicalRect,
+        clip_geometry: PhysicalRect,
+        commands: alloc::vec::Vec<path::Command>,
+        color: PremultipliedRgbaColor,
+    );
+    #[cfg(feature = "software-renderer-path")]
+    fn process_stroked_path(
+        &mut self,
+        path_geometry: PhysicalRect,
+        clip_geometry: PhysicalRect,
+        commands: alloc::vec::Vec<path::Command>,
+        color: PremultipliedRgbaColor,
+        stroke_width: f32,
+    );
 }
 
 fn process_rectangle_impl(
@@ -1681,6 +1700,36 @@ impl<B: target_pixel_buffer::TargetPixelBuffer> ProcessScene for RenderToBuffer<
             );
         });
     }
+
+    #[cfg(feature = "software-renderer-path")]
+    fn process_filled_path(
+        &mut self,
+        path_geometry: PhysicalRect,
+        clip_geometry: PhysicalRect,
+        commands: alloc::vec::Vec<path::Command>,
+        color: PremultipliedRgbaColor,
+    ) {
+        path::render_filled_path(&commands, &path_geometry, &clip_geometry, color, self.buffer);
+    }
+
+    #[cfg(feature = "software-renderer-path")]
+    fn process_stroked_path(
+        &mut self,
+        path_geometry: PhysicalRect,
+        clip_geometry: PhysicalRect,
+        commands: alloc::vec::Vec<path::Command>,
+        color: PremultipliedRgbaColor,
+        stroke_width: f32,
+    ) {
+        path::render_stroked_path(
+            &commands,
+            &path_geometry,
+            &clip_geometry,
+            color,
+            stroke_width,
+            self.buffer,
+        );
+    }
 }
 
 #[derive(Default)]
@@ -1814,6 +1863,31 @@ impl ProcessScene for PrepareScene {
             });
         }
     }
+
+    #[cfg(feature = "software-renderer-path")]
+    fn process_filled_path(
+        &mut self,
+        _path_geometry: PhysicalRect,
+        _clip_geometry: PhysicalRect,
+        _commands: alloc::vec::Vec<path::Command>,
+        _color: PremultipliedRgbaColor,
+    ) {
+        // Path rendering is not supported in line-by-line mode (PrepareScene/render_by_line)
+        // Only works with buffer-based rendering (RenderToBuffer)
+    }
+
+    #[cfg(feature = "software-renderer-path")]
+    fn process_stroked_path(
+        &mut self,
+        _path_geometry: PhysicalRect,
+        _clip_geometry: PhysicalRect,
+        _commands: alloc::vec::Vec<path::Command>,
+        _color: PremultipliedRgbaColor,
+        _stroke_width: f32,
+    ) {
+        // Path rendering is not supported in line-by-line mode (PrepareScene/render_by_line)
+        // Only works with buffer-based rendering (RenderToBuffer)
+    }
 }
 
 struct SceneBuilder<'a, T> {
@@ -2678,9 +2752,84 @@ impl<T: ProcessScene> crate::item_rendering::ItemRenderer for SceneBuilder<'_, T
         }
     }
 
-    #[cfg(feature = "std")]
-    fn draw_path(&mut self, _path: Pin<&crate::items::Path>, _: &ItemRc, _size: LogicalSize) {
-        // TODO
+    #[cfg(all(feature = "std", not(feature = "software-renderer-path")))]
+    fn draw_path(
+        &mut self,
+        _path: Pin<&crate::items::Path>,
+        _self_rc: &ItemRc,
+        _size: LogicalSize,
+    ) {
+        // Path rendering is disabled without the software-renderer-path feature
+    }
+
+    #[cfg(all(feature = "std", feature = "software-renderer-path"))]
+    fn draw_path(&mut self, path: Pin<&crate::items::Path>, self_rc: &ItemRc, size: LogicalSize) {
+        let geom = LogicalRect::from(size);
+        if !self.should_draw(&geom) {
+            return;
+        }
+
+        // Get the fitted path events from the Path item
+        let Some((offset, path_iterator)) = path.fitted_path_events(self_rc) else {
+            return;
+        };
+
+        // Convert to zeno commands
+        let zeno_commands = path::convert_path_data_to_zeno(path_iterator);
+
+        // Calculate the physical geometry
+        let physical_geom = (geom.translate(self.current_state.offset.to_vector()).cast()
+            * self.scale_factor)
+            .round()
+            .cast()
+            .transformed(self.rotation);
+
+        let physical_clip =
+            (self.current_state.clip.translate(self.current_state.offset.to_vector()).cast()
+                * self.scale_factor)
+                .round()
+                .cast::<i16>()
+                .transformed(self.rotation);
+
+        // Apply the offset from fitted path
+        let physical_offset = (offset.cast::<f32>() * self.scale_factor).cast::<i16>();
+        let adjusted_geom = physical_geom.translate(physical_offset);
+
+        // Clip the geometry - early return if nothing to draw
+        let Some(clipped_geom) = adjusted_geom.intersection(&physical_clip) else {
+            return;
+        };
+
+        // Draw fill if specified
+        let fill_brush = path.fill();
+        if !fill_brush.is_transparent() {
+            let fill_color = self.alpha_color(fill_brush.color());
+            if fill_color.alpha() > 0 {
+                self.processor.process_filled_path(
+                    adjusted_geom,
+                    clipped_geom,
+                    zeno_commands.clone(),
+                    fill_color.into(),
+                );
+            }
+        }
+
+        // Draw stroke if specified
+        let stroke_brush = path.stroke();
+        let stroke_width = path.stroke_width();
+        if !stroke_brush.is_transparent() && stroke_width.get() > 0.0 {
+            let stroke_color = self.alpha_color(stroke_brush.color());
+            if stroke_color.alpha() > 0 {
+                let physical_stroke_width = (stroke_width.cast() * self.scale_factor).get();
+                self.processor.process_stroked_path(
+                    adjusted_geom,
+                    clipped_geom,
+                    zeno_commands,
+                    stroke_color.into(),
+                    physical_stroke_width,
+                );
+            }
+        }
     }
 
     fn draw_box_shadow(

internal/core/software_renderer/path.rs

@@ -0,0 +1,171 @@
+// Copyright © SixtyFPS GmbH <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
+
+//! Path rendering support for the software renderer using zeno
+
+use super::draw_functions::{PremultipliedRgbaColor, TargetPixel};
+use super::PhysicalRect;
+#[cfg(feature = "std")]
+use crate::graphics::PathDataIterator;
+use alloc::vec::Vec;
+use zeno::{Fill, Mask, Stroke};
+
+pub use zeno::Command;
+
+/// Convert Slint's PathDataIterator to zeno's Command format
+#[cfg(feature = "std")]
+pub fn convert_path_data_to_zeno(path_data: PathDataIterator) -> Vec<Command> {
+    use lyon_path::Event;
+    use zeno::Point;
+    let mut commands = Vec::new();
+
+    for event in path_data.iter() {
+        match event {
+            Event::Begin { at } => {
+                commands.push(Command::MoveTo(Point::new(at.x, at.y)));
+            }
+            Event::Line { to, .. } => {
+                commands.push(Command::LineTo(Point::new(to.x, to.y)));
+            }
+            Event::Quadratic { ctrl, to, .. } => {
+                commands.push(Command::QuadTo(Point::new(ctrl.x, ctrl.y), Point::new(to.x, to.y)));
+            }
+            Event::Cubic { ctrl1, ctrl2, to, .. } => {
+                commands.push(Command::CurveTo(
+                    Point::new(ctrl1.x, ctrl1.y),
+                    Point::new(ctrl2.x, ctrl2.y),
+                    Point::new(to.x, to.y),
+                ));
+            }
+            Event::End { close, .. } => {
+                if close {
+                    commands.push(Command::Close);
+                }
+            }
+        }
+    }
+
+    commands
+}
+
+/// Common rendering logic for both filled and stroked paths
+fn render_path_with_style<T: TargetPixel>(
+    commands: &[Command],
+    path_geometry: &PhysicalRect,
+    clip_geometry: &PhysicalRect,
+    color: PremultipliedRgbaColor,
+    style: zeno::Style,
+    buffer: &mut impl crate::software_renderer::target_pixel_buffer::TargetPixelBuffer<TargetPixel = T>,
+) {
+    // The mask needs to be rendered at the full path size
+    let path_width = path_geometry.size.width as usize;
+    let path_height = path_geometry.size.height as usize;
+
+    if path_width == 0 || path_height == 0 {
+        return;
+    }
+
+    // Create a buffer for the mask output
+    let mut mask_buffer = Vec::with_capacity(path_width * path_height);
+    mask_buffer.resize(path_width * path_height, 0u8);
+
+    // Render the full path into the mask
+    Mask::new(commands)
+        .size(path_width as u32, path_height as u32)
+        .style(style)
+        .render_into(&mut mask_buffer, None);
+
+    // Calculate the intersection region - only apply within clipped area
+    // clip_geometry is relative to screen, path_geometry is also relative to screen
+    let clip_x_start = clip_geometry.origin.x.max(0) as usize;
+    let clip_y_start = clip_geometry.origin.y.max(0) as usize;
+    let clip_x_end = (clip_geometry.max_x().max(0) as usize).min(buffer.line_slice(0).len());
+    let clip_y_end = (clip_geometry.max_y().max(0) as usize).min(buffer.num_lines());
+
+    let path_x_start = path_geometry.origin.x as isize;
+    let path_y_start = path_geometry.origin.y as isize;
+
+    // Apply the mask only within the clipped region
+    for screen_y in clip_y_start..clip_y_end {
+        let line = buffer.line_slice(screen_y);
+
+        // Calculate the y coordinate in the mask buffer
+        let mask_y = screen_y as isize - path_y_start;
+        if mask_y < 0 || mask_y >= path_height as isize {
+            continue;
+        }
+
+        for screen_x in clip_x_start..clip_x_end {
+            // Calculate the x coordinate in the mask buffer
+            let mask_x = screen_x as isize - path_x_start;
+            if mask_x < 0 || mask_x >= path_width as isize {
+                continue;
+            }
+
+            let mask_idx = (mask_y as usize) * path_width + (mask_x as usize);
+            let coverage = mask_buffer[mask_idx];
+
+            if coverage > 0 {
+                // Scale all color components by coverage to maintain premultiplication
+                let coverage_factor = coverage as u16;
+                let alpha_color = PremultipliedRgbaColor {
+                    red: ((color.red as u16 * coverage_factor) / 255) as u8,
+                    green: ((color.green as u16 * coverage_factor) / 255) as u8,
+                    blue: ((color.blue as u16 * coverage_factor) / 255) as u8,
+                    alpha: ((color.alpha as u16 * coverage_factor) / 255) as u8,
+                };
+                T::blend(&mut line[screen_x], alpha_color);
+            }
+        }
+    }
+}
+
+/// Render a filled path
+///
+/// * `commands` - The path commands to render
+/// * `path_geometry` - The full bounding box of the path in screen coordinates
+/// * `clip_geometry` - The clipped region where the path should be rendered (intersection of path and clip)
+/// * `color` - The color to render the path
+/// * `buffer` - The target pixel buffer
+pub fn render_filled_path<T: TargetPixel>(
+    commands: &[Command],
+    path_geometry: &PhysicalRect,
+    clip_geometry: &PhysicalRect,
+    color: PremultipliedRgbaColor,
+    buffer: &mut impl crate::software_renderer::target_pixel_buffer::TargetPixelBuffer<TargetPixel = T>,
+) {
+    render_path_with_style(
+        commands,
+        path_geometry,
+        clip_geometry,
+        color,
+        zeno::Style::Fill(Fill::NonZero),
+        buffer,
+    );
+}
+
+/// Render a stroked path
+///
+/// * `commands` - The path commands to render
+/// * `path_geometry` - The full bounding box of the path in screen coordinates
+/// * `clip_geometry` - The clipped region where the path should be rendered (intersection of path and clip)
+/// * `color` - The color to render the path
+/// * `stroke_width` - The width of the stroke
+/// * `buffer` - The target pixel buffer
+pub fn render_stroked_path<T: TargetPixel>(
+    commands: &[Command],
+    path_geometry: &PhysicalRect,
+    clip_geometry: &PhysicalRect,
+    color: PremultipliedRgbaColor,
+    stroke_width: f32,
+    buffer: &mut impl crate::software_renderer::target_pixel_buffer::TargetPixelBuffer<TargetPixel = T>,
+) {
+    render_path_with_style(
+        commands,
+        path_geometry,
+        clip_geometry,
+        color,
+        zeno::Style::Stroke(Stroke::new(stroke_width)),
+        buffer,
+    );
+}