Flattened Text Group always has the identity abs_transform

[paxbun]

resvg version: 0.41

The group returned by Text::flattened always has the default abs_transform. usvg::text::flatten::flatten does not propagate the containing Text's abs_transform.

This does not affect resvg since resvg::render::render_group re-calculates abs_transform (Line 56).

resvg/crates/resvg/src/render.rs

Lines 50 to 61 in b908baf

	fn render_group(
	group: &usvg::Group,
	ctx: &Context,
	transform: tiny_skia::Transform,
	pixmap: &mut tiny_skia::PixmapMut,
	) -> Option<()> {
	let transform = transform.pre_concat(group.transform());
	if !group.should_isolate() {
	render_nodes(group, ctx, transform, pixmap);
	return Some(());
	}

All tests pass even after modifying usvg::text::flatten::flatten as follows.

        if let Some(path) = span_builder.finish().and_then(|p| {
            Path::new(
                String::new(),
                span.visibility,
                span.fill.clone(),
                span.stroke.clone(),
                span.paint_order,
                rendering_mode,
                Arc::new(p),
+++             text.abs_transform,
---             Transform::default(),
            )
        }) {
            stroke_bbox = stroke_bbox.expand(path.stroke_bounding_box());
            new_paths.push(path);
        }

        if let Some(path) = span.line_through.as_ref() {
            stroke_bbox = stroke_bbox.expand(path.data.bounds());
            let mut path = path.clone();
            path.rendering_mode = rendering_mode;
            new_paths.push(path);
        }
    }

    let mut group = Group {
        id: text.id.clone(),
+++     abs_transform: text.abs_transform,
        ..Group::empty()
    };

Is it intended to re-calculate abs_transform in resvg and keep abs_transform in Text::flattened default?

[RazrFalcon]

This is kinda intended. I will see what we can do about it.