Missing simpler examples/documentation

[LoganDark]

I'm trying to understand this library to see if it would be suitable for drawing into a softbuffer buffer. The problem is, I can only find full-featured SVG-drawing examples, when all I want to do is draw simple primitives for UI elements. Additionally, I can't find any helpful info in the documentation.

[aslpavel]

Here is a simple example that renders a squirrel with a frame around it

use rasterize::*;
use std::{fs::File, io::BufWriter, sync::Arc};

type Error = Box<dyn std::error::Error>;

fn main() -> Result<(), Error> {
    // Create path using builder
    let squirrel_path: Arc<Path> = Path::builder()
        .move_to((12.0, 1.0))
        .cubic_to((9.79, 1.0), (8.0, 2.31), (8.0, 3.92))
        .cubic_to((8.0, 5.86), (8.5, 6.95), (8.0, 10.0))
        .cubic_to((8.0, 5.5), (5.23, 3.66), (4.0, 3.66))
        .cubic_to((4.05, 3.16), (3.52, 3.0), (3.52, 3.0))
        .cubic_to((3.52, 3.0), (3.3, 3.11), (3.22, 3.34))
        .cubic_to((2.95, 3.03), (2.66, 3.07), (2.66, 3.07))
        .line_to((2.53, 3.65))
        .cubic_to((2.53, 3.65), (0.7, 4.29), (0.68, 6.87))
        .cubic_to((0.88, 7.2), (2.21, 7.47), (3.15, 7.3))
        .cubic_to((4.04, 7.35), (3.82, 8.09), (3.62, 8.29))
        .cubic_to((2.78, 9.13), (2.0, 8.0), (1.0, 8.0))
        .cubic_to((0.0, 8.0), (0.0, 9.0), (1.0, 9.0))
        .cubic_to((2.0, 9.0), (2.0, 10.0), (4.0, 10.0))
        .cubic_to((0.91, 11.2), (4.0, 14.0), (4.0, 14.0))
        .line_to((3.0, 14.0))
        .cubic_to((2.0, 14.0), (2.0, 15.0), (2.0, 15.0))
        .line_to((8.0, 15.0))
        .cubic_to((11.0, 15.0), (13.0, 14.0), (13.0, 11.53))
        .cubic_to((13.0, 10.68), (12.57, 9.74), (12.0, 9.0))
        .cubic_to((10.89, 7.54), (12.23, 6.32), (13.0, 7.0))
        .cubic_to((13.77, 7.68), (16.0, 8.0), (16.0, 5.0))
        .cubic_to((16.0, 2.79), (14.21, 1.0), (12.0, 1.0))
        .close()
        .move_to((2.5, 6.0))
        .cubic_to((2.22, 6.0), (2.0, 5.78), (2.0, 5.5))
        .cubic_to((2.0, 5.22), (2.22, 5.0), (2.5, 5.0))
        .cubic_to((2.78, 5.0), (3.0, 5.22), (3.0, 5.5))
        .cubic_to((3.0, 5.78), (2.78, 6.0), (2.5, 6.0))
        .close()
        .build()
        .into();
    // Squirrels bounding box
    let squirrel_bbox = squirrel_path
        .bbox(Transform::identity())
        .ok_or("Empty path")?;

    // Construct squirrel scene stroke and fill
    let squirrel_scene = Scene::group(vec![
        Scene::fill(
            squirrel_path.clone(),
            Arc::new("#d65d0e".parse::<LinColor>()?),
            FillRule::default(),
        ),
        Scene::stroke(
            squirrel_path,
            Arc::new("#af3a03".parse::<LinColor>()?),
            StrokeStyle {
                width: 0.3,
                line_join: LineJoin::default(),
                line_cap: LineCap::Round,
            },
        ),
    ])
    // fit it into 200x200 box with 10 pixel margin
    .transform(Transform::fit_bbox(
        squirrel_bbox,
        BBox::new((10.0, 10.0), (190.0, 190.0)),
        Align::Mid,
    ));

    // Construct frame around squirrel
    let frame_scene = Scene::stroke(
        Path::builder()
            .move_to((5.0, 5.0))
            .rbox((190.0, 190.0), (15.0, 15.0))
            .build()
            .into(),
        Arc::new("#98971a".parse::<LinColor>()?),
        StrokeStyle {
            width: 2.0,
            line_join: LineJoin::default(),
            line_cap: LineCap::Round,
        },
    );

    // Construct full scene
    let scene =
        Scene::group(vec![frame_scene, squirrel_scene]).transform(Transform::new_scale(2.0, 2.0));

    // Render image
    let image = scene.render(
        &ActiveEdgeRasterizer::default(),
        Transform::identity(),
        Some(BBox::new((0.0, 0.0), (400.0, 400.0))),
        Some("#fbf1c7".parse()?),
    );

    // Write file
    //
    // Image pixels can also be iterated with
    // `for pixel in image.iter().map(Color::to_rgb) { ... }`
    let mut output = BufWriter::new(File::create("squirrel.bmp")?);
    image.write_bmp(&mut output)?;

    Ok(())
}

And here is the result:

I will add this to examples. Please let me know if you have any more questions.

[LoganDark]

What is a "scene"? Is it a filled shape / area?

[aslpavel]

Path is what can be filled (squirrel path is filled with orange color) or stroked (and also stroked with dark orange color) and represents shape. The easiest way to construct it is to use Path::builder() ... .build() or parse from an existing SVG Path with "...".parse::<Path>(). You can think of a scene as something that represents an image but it has not been rendered yet. You can group different scenes with Scene::group it can also be transformed (scaled, translated, rotated etc) with Scene::transform, it also supports clipping with Scene::clip (restrict a scene as if it can only be drawn inside a particular path). You can also fill/stroke shape with a radial/linear gradient. In general the model of this crate is similar to the SVG model.

[LoganDark]

You can think of a scene as something that represents an image but it has not been rendered yet.

So a scene is like a command buffer?

[aslpavel]

Sort of but I would describe it as a tree of shapes with additional details required for rendering, that can be converted to something like command buffer, it is traversed in the depth first order when rendered.

[aslpavel]

One thing to note Path can represent more than one shape that all rendered at once. For example data/material-big.path represents thousands of shapes that are represented as single path.

[LoganDark]

OK, thank you! :)