vectorcraft/crates/effects/src/reshape.rs

//! Object-level effects on objects that aren't paths: type, placed images, symbol instances and
//! live objects (blends, envelopes, meshes, repeats).
//!
//! Geometry effects reach them through outlines: [`outline_art`] turns the object into plain paths
//! (glyph outlines, the evaluated live object, the symbol's art) and [`reshape`] runs each effect
//! over all of them as one piece, with the whole art's bounds as the effect's reference box, so a
//! warp bends a line of type as a whole. An image is clipped by its reshaped frame. Raster effects
//! (shadows, glows, blur, feather) stay on the result for the renderer and exporters.

use std::sync::Arc;

use vectorcraft_doc::{Appearance, AppearanceItem, Effect, Node, NodeKind};
use vectorcraft_geom::{Affine, FillRule, PathData, Rect, shapes};

use crate::{GeomContext, apply_one, is_geometry, merged_params};

/// Can object-level effects apply to `n` only through [`outline_art`] / an offscreen layer (it is
/// neither a path nor a container)?
pub fn needs_outline(n: &Node) -> bool {
    matches!(
        n.kind,
        NodeKind::Text(_)
            | NodeKind::Image(_)
            | NodeKind::SymbolInstance { .. }
            | NodeKind::Blend { .. }
            | NodeKind::Envelope { .. }
            | NodeKind::Mesh(_)
            | NodeKind::Repeat(_)
            | NodeKind::PlacedDocument(_)
    )
}

/// The glyph outlines of type `t` in text space with its underline and strikethrough bars: one
/// path per run, and all of them as one.
pub(crate) fn glyph_outlines(t: &vectorcraft_doc::TextObject) -> (Vec<kurbo::BezPath>, kurbo::BezPath) {
    let (runs, all, _) = laid_out(t);
    (runs, all)
}

/// [`glyph_outlines`] and the bounds of `t`'s layout in text space.
fn laid_out(t: &vectorcraft_doc::TextObject) -> (Vec<kurbo::BezPath>, kurbo::BezPath, Rect) {
    let db = vectorcraft_text::FontDb::global();
    let layout = vectorcraft_text::layout(db, t);
    let mut runs = vec![kurbo::BezPath::new(); t.runs.len()];
    let mut all = kurbo::BezPath::new();
    for g in &layout.glyphs {
        if let Some(r) = runs.get_mut(g.run) {
            r.extend(g.outline.iter());
        }
        all.extend(g.outline.iter());
    }
    // Underline and strikethrough bars, painted as their run's type is (#847).
    for (run, bar) in vectorcraft_text::decorations(&layout, db, t) {
        if let Some(r) = runs.get_mut(run) {
            r.extend(bar.iter());
        }
        all.extend(bar.iter());
    }
    (runs, all, layout.bounds)
}

/// Type as glyph outlines in document space: one path per run with the run's fill and stroke,
/// and (when the object has its own fills/strokes) the whole outline with the object's items below
/// the characters under them and the others over them, as the renderer paints them. Each run's
/// path is placed by the type's transform, which also scales its stroke weights and dashes and
/// transforms its pattern tiles; its unplaced gradients are first fixed to the layout's bounds in
/// text space. The object's own unplaced gradients are fixed to the bounding box of those bounds
/// in the document. The group is marked as type's outlines
/// ([`vectorcraft_doc::NodeExtras::type_outlines`]).
pub fn outline_text(n: &Node) -> Option<Node> {
    let NodeKind::Text(t) = &n.kind else { return None };
    let (runs, all, bounds) = laid_out(t);
    let path = |bp: &kurbo::BezPath| PathData::from_bezpath(bp).transformed(t.xf);
    let scaling = vectorcraft_doc::Scaling { strokes: true, patterns: true, ..Default::default() };
    let mut children: Vec<Arc<Node>> = runs
        .iter()
        .zip(&t.runs)
        .filter(|(bp, _)| !bp.elements().is_empty())
        .map(|(bp, run)| {
            let mut ap = run.style.appearance();
            ap.pin_gradients(bounds);
            let mut piece = Node::path(n.id, PathData::from_bezpath(bp), ap);
            piece.transform(t.xf, scaling);
            Arc::new(piece)
        })
        .collect();
    if !n.appearance.items.is_empty() && !all.elements().is_empty() {
        let (below, above) = n.appearance.split_contents();
        let tb = t.xf.transform_rect_bbox(bounds);
        let glyphs = |items: &[AppearanceItem]| {
            let mut ap = Appearance { items: items.to_vec(), ..Default::default() };
            ap.pin_gradients(tb);
            Arc::new(Node::path(n.id, path(&all), ap))
        };
        if !below.is_empty() {
            children.insert(0, glyphs(below));
        }
        if !above.is_empty() {
            children.push(glyphs(above));
        }
    }
    let mut g = Node::group(n.id, children);
    g.extras_mut().type_outlines = true;
    Some(g)
}

/// `n` as plain art that geometry effects can reshape, without its transparency and object
/// effects: type outlined ([`outline_text`]), live objects evaluated (type inside them outlined),
/// a symbol instance as `symbol_art` (the symbol's art, stained as the caller draws it) placed by
/// the instance's transform. `None` for other kinds (images, paths, containers).
pub fn outline_art(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
    let hook: &dyn Fn(&Node) -> Option<Node> = &outline_text;
    let mut art = match &n.kind {
        NodeKind::Text(_) => outline_text(n)?,
        NodeKind::SymbolInstance { xf, .. } => {
            let mut a = symbol_art?.clone();
            a.transform(*xf, false);
            Node::group(n.id, vec![Arc::new(a)])
        }
        _ if vectorcraft_doc::live::is_live(n) => vectorcraft_doc::live::expand_deep(n, Some(hook)),
        _ => return None,
    };
    outline_nested_text(&mut art, false);
    art.opacity = 1.0;
    art.blend = Default::default();
    art.isolate = false;
    // One element: its pieces never knock each other out.
    art.knockout = vectorcraft_doc::Knockout::Off;
    art.extras_mut().mask = None;
    art.appearance.effects.clear();
    Some(art)
}

/// Replace type anywhere inside `n` by its outlines, as art that keeps the type's look
/// ([`as_art`]). Type in a clip group's clipping path (all of `n` when `clipping` is set) becomes
/// its plain outlines ([`outline_text`]) with its visibility, which is what
/// [`crate::clip_outline`] clips by.
fn outline_nested_text(n: &mut Node, clipping: bool) {
    let clips = n.clips();
    let Some(ch) = n.children_mut() else { return };
    for (i, c) in ch.iter_mut().enumerate() {
        let clipping = clipping || (clips && i == 0);
        let art = match &c.kind {
            NodeKind::Text(_) if clipping => outline_text(c).map(|o| Node { visible: c.visible, ..o }),
            NodeKind::Text(_) => as_art(c, None),
            _ => None,
        };
        if let Some(o) = art {
            *c = Arc::new(o);
        } else if c.children().is_some() {
            outline_nested_text(Arc::make_mut(c), clipping);
        }
    }
}

/// `n` (see [`needs_outline`]) with its object-level geometry effects and its perspective applied:
/// its [`outline_art`] reshaped as one piece, or for an image the image clipped by its reshaped
/// frame. The result is a group with `n`'s id, name, visibility, transparency, opacity mask and
/// remaining (raster) effects; `None` when `n` has neither a visible geometry effect nor a
/// perspective, or has no art (a symbol instance without `symbol_art`).
pub fn reshape(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
    if (geometry_effects(n).is_empty() && n.projection().is_none()) || !needs_outline(n) {
        return None;
    }
    as_art(n, symbol_art)
}

/// `n` (see [`needs_outline`]) as plain art for Expand Appearance: [`reshape`]d when it has
/// geometry effects, else type with fills or strokes of its own outlined, in the same form. `None`
/// when it has neither.
pub fn expand_outlined(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
    let own_paint = matches!(n.kind, NodeKind::Text(_)) && !n.appearance.items.is_empty();
    if !needs_outline(n) || (geometry_effects(n).is_empty() && !own_paint) {
        return None;
    }
    as_art(n, symbol_art)
}

/// [`reshape`] without its checks (no geometry effects: just the art).
pub(crate) fn as_art(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
    let fx = geometry_effects(n);
    let mut art = match &n.kind {
        NodeKind::Image(im) => {
            let frame = shapes::rectangle(Rect::new(0.0, 0.0, im.width as f64, im.height as f64)).transformed(im.xf);
            let mut clip = Node::path(n.id, frame, Appearance::default());
            if let NodeKind::Path { clipping, .. } = &mut clip.kind {
                *clipping = true;
            }
            let image = Node::new(n.id, n.kind.clone());
            Node::new(n.id, NodeKind::Group { children: vec![Arc::new(clip), Arc::new(image)], clip: true })
        }
        _ => outline_art(n, symbol_art)?,
    };
    reshape_leaves(&mut art, &fx);
    // Type and symbols in perspective: the art projected onto their plane.
    if let Some(h) = n.projection() {
        project_leaves(&mut art, &h);
    }
    // The art is a group with `n`'s id (a clip group for an image).
    let mut out = art;
    out.name = n.name.clone();
    out.visible = n.visible;
    out.opacity = n.opacity;
    out.blend = n.blend;
    out.isolate = n.isolate;
    // One element: its pieces never knock each other out.
    out.knockout = vectorcraft_doc::Knockout::Off;
    out.knockout_shape = n.knockout_shape;
    out.extras_mut().mask = n.extras().mask.clone();
    out.appearance.effects = n.appearance.effects.iter().filter(|e| !is_geometry(&e.id)).cloned().collect();
    Some(out)
}

/// Map every path under `art` (and its gradients) through the projective map `h`, curves split
/// finely enough to follow it.
fn project_leaves(art: &mut Node, h: &vectorcraft_geom::Homography) {
    let f = |p: vectorcraft_geom::Point| h.apply(p).unwrap_or(p);
    let piece = art.geometric_bounds().map_or(1.0, |b| (b.width().max(b.height()) / 64.0).max(0.25));
    let project = |path: &mut PathData| *path = vectorcraft_doc::live::map_nonlinear(path, piece, f);
    for_each_leaf(art, &mut |leaf| {
        leaf.pin_gradients();
        leaf.appearance.warp_gradients(&|p| h.affine_at(p).unwrap_or(vectorcraft_geom::Affine::IDENTITY));
        match &mut leaf.kind {
            NodeKind::Path { path, live, .. } => {
                project(path);
                *live = None;
            }
            NodeKind::Compound { children, .. } => {
                for c in children.iter_mut() {
                    if let NodeKind::Path { path, live, .. } = &mut Arc::make_mut(c).kind {
                        project(path);
                        *live = None;
                    }
                }
            }
            _ => {}
        }
    });
}

/// The visible geometry effects of `n`'s own effect list, in order.
pub(crate) fn geometry_effects(n: &Node) -> Vec<&Effect> {
    n.appearance.effects.iter().filter(|e| e.visible && is_geometry(&e.id)).collect()
}

/// Apply `fx` to every path under `art` as one piece: each effect takes the whole art's bounds as
/// its reference box and the art's seed (a random Transform moves the pieces together). Images
/// follow a Transform effect the same way ([`transform_images`]); other geometry effects leave
/// them as they are (a raster follows a non-affine map only as a mesh warp).
pub(crate) fn reshape_leaves(art: &mut Node, fx: &[&Effect]) {
    let seed = art.id.0;
    // The placed gradients of type's outlines in `art` (`outline_text`) move and scale with the
    // pieces, from the outlines' bounds before the effects to their bounds after them.
    let mut outlines = vec![];
    type_outline_bounds(art, &mut outlines);
    for e in fx {
        let Some(bounds) = art.geometric_bounds() else { break };
        let params = merged_params(&e.id, &e.params);
        for_each_leaf(art, &mut |leaf| {
            let Some((path, rule)) = leaf_geometry(leaf) else { return };
            let out = apply_one(&e.id, &params, &path, bounds, &GeomContext { seed, ..GeomContext::of(leaf) });
            set_geometry(leaf, out, rule);
        });
        if e.id == "distort.transform" {
            let (m, copies) = crate::distort::transform_map(bounds, &params, seed);
            transform_images(art, m, copies);
        }
    }
    if !fx.is_empty() && outlines.iter().any(Option::is_some) {
        rebase_type_outlines(art, &mut outlines.into_iter());
    }
}

/// The bounds of each group of type's outlines under `n` ([`outline_text`]), `n` included, in
/// order. A group inside one of them is part of it.
fn type_outline_bounds(n: &Node, out: &mut Vec<Option<Rect>>) {
    if n.extras().type_outlines {
        out.push(n.geometric_bounds());
    } else if let NodeKind::Group { children, .. } | NodeKind::Layer { children, .. } = &n.kind {
        for c in children {
            type_outline_bounds(c, out);
        }
    }
}

/// Move and scale the placed gradients of each group of type's outlines under `n` from its bounds
/// in `before` ([`type_outline_bounds`] before its paths changed) to its bounds now.
fn rebase_type_outlines(n: &mut Node, before: &mut std::vec::IntoIter<Option<Rect>>) {
    if !n.extras().type_outlines {
        if let NodeKind::Group { children, .. } | NodeKind::Layer { children, .. } = &mut n.kind {
            for c in children.iter_mut() {
                rebase_type_outlines(Arc::make_mut(c), before);
            }
        }
    } else if let Some(Some(from)) = before.next()
        && let Some(to) = n.geometric_bounds()
        && from != to
    {
        for_each_leaf(n, &mut |leaf| {
            if leaf.appearance.has_placed_gradient() {
                follow_boxes(&mut leaf.appearance, from, to);
            }
        });
    }
}

/// Map the placed gradients of `ap` from box `from` to box `to` through the map that takes one box
/// onto the other (strokes: their stroke-inflated boxes). The start and end go where
/// [`Appearance::rebase_gradients`] puts them, and a radial's ellipse and a linear's isolines are
/// mapped with them.
fn follow_boxes(ap: &mut Appearance, from: Rect, to: Rect) {
    for i in &mut ap.items {
        match i {
            AppearanceItem::Fill(f) => {
                if let vectorcraft_doc::color::Paint::Gradient(g) = &mut f.paint {
                    g.transform(box_map(from, to));
                }
            }
            AppearanceItem::Stroke(s) => {
                let m = box_map(s.paint_bounds(from), s.paint_bounds(to));
                if let vectorcraft_doc::color::Paint::Gradient(g) = &mut s.paint {
                    g.transform(m);
                }
            }
        }
    }
}

/// The map that takes box `from` onto box `to` along each axis (along an axis `from` has no extent
/// on, a move from its center to `to`'s).
fn box_map(from: Rect, to: Rect) -> vectorcraft_geom::Affine {
    let axis = |a0: f64, a1: f64, b0: f64, b1: f64| {
        if (a1 - a0).abs() > 1e-12 {
            let s = (b1 - b0) / (a1 - a0);
            (s, b0 - a0 * s)
        } else {
            (1.0, (b0 + b1 - a0 - a1) / 2.0)
        }
    };
    let (sx, tx) = axis(from.x0, from.x1, to.x0, to.x1);
    let (sy, ty) = axis(from.y0, from.y1, to.y0, to.y1);
    vectorcraft_geom::Affine::new([sx, 0.0, 0.0, sy, tx, ty])
}

/// Apply the Transform effect's map `m` to every image under `n`, as [`for_each_leaf`] does to
/// paths: the map goes into the image's placement (pixel space → document), and `copies` more
/// images follow, each mapped once more than the last. Without copies the image itself takes the
/// map, as a path does.
fn transform_images(n: &mut Node, m: Affine, copies: usize) {
    transform_images_within(n, m, copies, crate::distort::MAX_COPY_IMAGES)
}

/// [`transform_images`] whose copies make at most `max` image nodes of the art, the originals
/// included: each copy adds the image once more, and a Transform after this one copies the lot
/// again, so copies stop where the result would pass `max` (#2042).
pub(crate) fn transform_images_within(n: &mut Node, m: Affine, copies: usize, max: usize) {
    let mut room = max.saturating_sub(image_count(n));
    copy_images(n, m, copies, &mut room);
}

/// The walk of [`transform_images`]: the map and its copies go to each image in document order,
/// each copy taking one from `room` (what the art can still grow by), until the budget is full.
fn copy_images(n: &mut Node, m: Affine, copies: usize, room: &mut usize) {
    let Some(children) = n.children_mut() else { return };
    for c in children.iter_mut() {
        if !matches!(c.kind, NodeKind::Image(_)) {
            copy_images(Arc::make_mut(c), m, copies, room);
            continue;
        }
        let src = (**c).clone();
        let placed = |xf: Affine| {
            let mut one = src.clone();
            if let NodeKind::Image(im) = &mut one.kind {
                im.xf = xf * im.xf;
            }
            one
        };
        if copies == 0 {
            *c = Arc::new(placed(m));
            continue;
        }
        let made = copies.min(*room);
        *room -= made;
        // The copies become image nodes of their own, under a group with the image's id, name and
        // place in the art (as the runs an outlined text gets).
        let mut images: Vec<Arc<Node>> = Vec::with_capacity(made + 1);
        images.push(Arc::new(placed(Affine::IDENTITY)));
        let mut xf = Affine::IDENTITY;
        for _ in 0..made {
            xf *= m;
            images.push(Arc::new(placed(xf)));
        }
        let mut g = Node::group(src.id, images);
        g.name = src.name.clone();
        *c = Arc::new(g);
    }
}

/// How many image nodes `n` holds below itself.
fn image_count(n: &Node) -> usize {
    n.children().into_iter().flatten().map(|c| usize::from(matches!(c.kind, NodeKind::Image(_))) + image_count(c)).sum()
}

/// `n` with type anywhere inside it outlined and live objects evaluated, so geometry effects on
/// it reach every member.
pub(crate) fn outlined_members(n: &Node) -> Node {
    let hook: &dyn Fn(&Node) -> Option<Node> = &outline_text;
    let mut art = vectorcraft_doc::live::expand_deep(n, Some(hook));
    outline_nested_text(&mut art, false);
    art
}

/// Run `f` on every path and compound path under `n` (guides skipped).
fn for_each_leaf(n: &mut Node, f: &mut dyn FnMut(&mut Node)) {
    match &mut n.kind {
        NodeKind::Path { guide: false, .. } | NodeKind::Compound { .. } => f(n),
        NodeKind::Group { children, .. } | NodeKind::Layer { children, .. } => {
            for c in children.iter_mut() {
                for_each_leaf(Arc::make_mut(c), f);
            }
        }
        _ => {}
    }
}

pub(crate) fn leaf_geometry(n: &Node) -> Option<(PathData, FillRule)> {
    match &n.kind {
        NodeKind::Path { path, rule, .. } => Some((path.clone(), *rule)),
        NodeKind::Compound { children, rule } => {
            Some((PathData::new(children.iter().filter_map(|c| c.path_data()).flat_map(|p| p.subpaths.iter().cloned()).collect()), *rule))
        }
        _ => None,
    }
}

/// Replace the geometry of path or compound `n` (a compound when `path` has several subpaths).
fn set_geometry(n: &mut Node, path: PathData, rule: FillRule) {
    let clipping = matches!(n.kind, NodeKind::Path { clipping: true, .. });
    n.kind = if path.subpaths.len() > 1 {
        let id = n.id;
        let children = path.subpaths.into_iter().map(|sp| Arc::new(Node::path(id, PathData::single(sp), Appearance::default()))).collect();
        NodeKind::Compound { children, rule }
    } else {
        NodeKind::Path { path, rule, live: None, clipping, guide: false }
    };
}