Lyon_path usage

NeymanPros · March 19, 2025, 4:57pm

Hi! I kind of figure out how to work with widget::canvas, where I have to create a canvas::Path and cover it so it will be ok for fn draw. Now I noticed there are vector graphic tools inside lyon_path. Tutorials have a good demonstration how to build paths, but it’s not clear what to do next. Building inside draw function doesn’t seems to work, as long as lyon_path::Path != canvas::Path, frame can’t take it, and I don’t think I can use it somewhere else. Are there any finished application examples where lyon_path is used?

airstrike · March 19, 2025, 5:03pm

You don’t need to use lyon_path, you’re supposed to use canvas::Path

Last year I built a toy app for an assignment called pathfinder (pun unintended )

Here’s the relevant bit of code to draw the polygons on the board:

github.com/airstrike/pathfinder

src/polygon.rs

85ba0cb54


      
          /// Draw the [`Polygon`] on a canvas [`Frame`] at a given index
          pub fn draw(&self, index: usize, frame: &mut Frame) {
              let fill_color = COLORS[index % COLORS.len()];
              let stroke_color = darken(fill_color, 0.5);
          
              let path = Path::new(|p| {
                  for (i, vertex) in self.vertices.iter().enumerate() {
                      if i == 0 {
                          p.move_to((vertex.x as f32, -vertex.y as f32).into());
                      } else {
                          p.line_to((vertex.x as f32, -vertex.y as f32).into());
                      }
                  }
                  p.close();
              });
          
              frame.fill(&path, Fill::from(fill_color));
              frame.stroke(&path, Stroke::default().with_color(stroke_color));
          
              let center = self.center();

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NeymanPros · March 19, 2025, 5:19pm

Thanks for the fast reply! I have no trouble with using common canvas::Path. But it is fully raster, and I would like to use vector graphic from lyon_path

hecrj · March 19, 2025, 5:41pm

canvas::Path is vectorial; it gets turned into a lyon path internally before rendering.