Unable to draw accurate bounding boxes

[Tameflame]

I've got an SVG (see attached image below), which has a lot of nested SVGs to emulate layers (I do this because I want to specify width/height and I can't do that with g tags), but the the following draw bboxes function fails to draw the boundary boxes correctly (see attached output below).

Here is my function:

pub fn render_svg_with_bboxes_to_png(input_path: &str, output_path: &str) {
    let zoom = 1.0;
    let mut opt = usvg::Options::default();
    // Get file's absolute directory.
    opt.resources_dir = std::fs::canonicalize(input_path)
        .ok()
        .and_then(|p| p.parent().map(|p| p.to_path_buf()));

    let mut fontdb = fontdb::Database::new();
    fontdb.load_system_fonts();

    let svg_data = std::fs::read(&input_path).unwrap();
    let tree = usvg::Tree::from_data(&svg_data, &opt, &fontdb).unwrap();

    let mut bboxes = Vec::new();
    let mut stroke_bboxes = Vec::new();
    collect_bboxes(tree.root(), &mut bboxes, &mut stroke_bboxes);

    let pixmap_size = tree.size().to_int_size().scale_by(zoom).unwrap();
    let mut pixmap =
        tiny_skia::Pixmap::new(pixmap_size.width(), pixmap_size.height())
            .unwrap();
    let render_ts = tiny_skia::Transform::from_scale(zoom, zoom);
    resvg::render(&tree, render_ts, &mut pixmap.as_mut());

    let mut stroke = tiny_skia::Stroke::default();
    stroke.width = 1.0 / zoom; // prevent stroke scaling as well

    let mut paint1 = tiny_skia::Paint::default();
    paint1.set_color_rgba8(255, 0, 0, 127);

    let mut paint2 = tiny_skia::Paint::default();
    paint2.set_color_rgba8(0, 200, 0, 127);

    let root_ts = tree.view_box().to_transform(tree.size());
    let bbox_ts = render_ts.pre_concat(root_ts);

    for bbox in bboxes {
        let path = tiny_skia::PathBuilder::from_rect(bbox);
        pixmap.stroke_path(&path, &paint1, &stroke, bbox_ts, None);
    }

    for bbox in stroke_bboxes {
        let path = tiny_skia::PathBuilder::from_rect(bbox);
        pixmap.stroke_path(&path, &paint2, &stroke, bbox_ts, None);
    }

    pixmap.save_png(&output_path).unwrap();
}

fn collect_bboxes(
    parent: &usvg::Group,
    bboxes: &mut Vec<usvg::Rect>,
    stroke_bboxes: &mut Vec<usvg::Rect>,
) {
    for node in parent.children() {
        if let usvg::Node::Group(ref group) = node {
            collect_bboxes(group, bboxes, stroke_bboxes);
        }

        let bbox = node.abs_bounding_box();
        bboxes.push(bbox);

        let stroke_bbox = node.abs_stroke_bounding_box();
        if bbox != stroke_bbox {
            stroke_bboxes.push(stroke_bbox);
        }
    }
}

Source svg file:

Output png file:

If the solution is to change my use of nested SVG tags, please advise, I really need them to emulate layers because I want to be able to programmatically modify the SVG. If the issue can be solved by adding attributes to specific tags or something like that please let me know. Thanks

[RazrFalcon]

Well, the image is rendered correctly, therefore SVG was parsed correctly. That's something. I guess something is wrong with usvg API. Will take a look.

[RazrFalcon]

Should be fixed in the next release.

[Tameflame]

Awesome thanks very much!

[Tameflame]

Btw @RazrFalcon, if I wanted to draw the bounding box for a specific node in the tree, is there a way to do that? I basically want to use the bounding boxes as a quick way of getting the intrinsic size of a node on the tree. Can I use nodeID or something?

[RazrFalcon]

You can use usvg::Tree::node_by_id.

[Tameflame]

@RazrFalcon thanks but for some reason I can't get it to fetch even a simple node:

#[test]
pub fn find_text_node_by_id() {
    let svg = r#"
    <svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
        <svg id="unique">
            <text x="10" y="10">Hello World</text>
        </svg>
    </svg>
    "#;

    let tree = usvg::Tree::from_str(
        svg,
        &usvg::Options::default(),
        &Default::default(),
    )
    .unwrap();

    println!("{:#?}", tree.node_by_id("unique"));
}

Output:

running 1 test
None
test tests::find_text_node_by_id ... ok

[RazrFalcon]

It's not a simple node. Nested svg elements are very complicated and in this case usvg looses the id. Will fix.

[Tameflame]

Awesome, thanks so much!

[RazrFalcon]

See #734