Export: the art's bounds take in the effects of groups, type and images

The bounds of the visible art (`vectorcraft_render::encode::art_bounds`)
are the crop of Export with Use Artboards off, EPS without artboards,
Export for Screens' Full Document and Save for Web (Legacy) with Clip to
Artboard off, and the size Fit to Artwork Bounds gives an artboard. They
measured a group or layer by its members and left out its own effects,
and measured type and images without their effects. A group's drop
shadow, or the shadow of a line of type, was cut off at the image's edge
and left outside the fitted artboard. They also counted a Shaper group's
transparent source art.

Each visible object is now measured by `vectorcraft_render::effect_bounds`,
the measure of Export Selection's crop. A group or layer without effects
of its own is still measured by its visible members, skipping a Shaper
group's source art. A group or layer with a drop shadow, a glow or another
raster effect is measured without its hidden members, guides and template
layers, unless it is a Shaper group or also has a geometry, Pathfinder,
Crop Marks or 3D effect or a visible effect on its own fill or stroke.
The SVG of a chosen artboard also keeps an object whose effects alone
reach the artboard.

Docs: docs/mcp.md, docs/target-app-parity.md.

crates/render/src/encode/tests.rs

@@ -244,6 +244,87 @@ fn art_bounds_take_in_the_effects_in_a_symbols_art() {
     assert!(b.x0 <= 20.0 && b.x1 >= 38.0, "the art from x 20 and its shadow to x 38: {b:?}");
 }
 
+/// A drop shadow 8 pt to the right, without blur.
+fn shadow_right() -> vectorcraft_doc::Effect {
+    vectorcraft_doc::Effect { id: "stylize.dropShadow".into(), params: serde_json::json!({"x": 8, "y": 0, "blur": 0}), visible: true }
+}
+
+#[test]
+fn art_bounds_take_in_the_effects_of_groups_type_and_images() {
+    let black = Appearance::basic(Paint::solid(Color::BLACK), Paint::None, 0.0);
+    let mut d = Document::new(100.0, 100.0);
+    let square = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(10.0, 10.0, 20.0, 20.0)), black);
+    let group = Node::group(d.alloc_id(), vec![std::sync::Arc::new(square)]);
+    let t = TextObject::point(Point::new(10.0, 40.0), "Hill", CharStyle { size: 12.0, ..CharStyle::default() });
+    let text = Node::new(d.alloc_id(), NodeKind::Text(Box::new(t)));
+    let im = vectorcraft_doc::ImageObject {
+        key: "image".into(),
+        width: 30,
+        height: 30,
+        xf: vectorcraft_geom::Affine::translate((20.0, 50.0)),
+        link: None,
+        placement: Default::default(),
+    };
+    let image = Node::new(d.alloc_id(), NodeKind::Image(Box::new(im)));
+    let cut_off: Vec<_> = [("group", group), ("type", text), ("image", image)]
+        .into_iter()
+        .filter_map(|(what, mut n)| {
+            let mut d = d.clone();
+            let plain = n.visual_bounds().unwrap();
+            n.appearance.effects.push(shadow_right());
+            let l = d.layers[0].id;
+            d.insert(Some(l), 0, n).unwrap();
+            let b = art_bounds(&d).unwrap();
+            (b.x0 > plain.x0 || b.x1 < plain.x1 + 8.0).then(|| format!("{what}: {b:?}, the shadow 8 pt right of {plain:?}"))
+        })
+        .collect();
+    assert!(cut_off.is_empty(), "{cut_off:?}");
+}
+
+#[test]
+fn art_bounds_leave_out_the_hidden_members_of_a_group_with_effects() {
+    let black = Appearance::basic(Paint::solid(Color::BLACK), Paint::None, 0.0);
+    let mut d = Document::new(100.0, 100.0);
+    let square = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(10.0, 10.0, 20.0, 20.0)), black.clone());
+    let mut hidden = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(200.0, 10.0, 220.0, 20.0)), black.clone());
+    hidden.visible = false;
+    let mut guide = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(-300.0, 10.0, -200.0, 20.0)), black);
+    if let NodeKind::Path { guide: g, .. } = &mut guide.kind {
+        *g = true;
+    }
+    let mut group = Node::group(d.alloc_id(), [square, hidden, guide].map(std::sync::Arc::new).to_vec());
+    // A geometry effect on the group's own fill that is turned off.
+    group.appearance = Appearance::basic(Paint::None, Paint::None, 0.0).into();
+    group.appearance.effects.push(shadow_right());
+    let off = vectorcraft_doc::Effect { id: "distort.transform".into(), params: serde_json::json!({"scaleH": 50}), visible: false };
+    group.appearance.fill_mut().unwrap().effects.push(off);
+    let l = d.layers[0].id;
+    d.insert(Some(l), 0, group).unwrap();
+    let b = art_bounds(&d).unwrap();
+    assert!(b.x0 >= 0.0 && (28.0..50.0).contains(&b.x1), "the square and its shadow, not the hidden square or the guide: {b:?}");
+}
+
+#[test]
+fn art_bounds_hold_a_groups_geometry_effect_measured_with_its_hidden_members() {
+    // The Transform effect halves the group's width about the center of all its members, the
+    // hidden one too: the visible rectangle is drawn from x 30 to x 80.
+    let black = Appearance::basic(Paint::solid(Color::BLACK), Paint::None, 0.0);
+    let mut d = Document::new(200.0, 100.0);
+    let shown = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(0.0, 10.0, 100.0, 20.0)), black.clone());
+    let mut hidden = Node::path(d.alloc_id(), shapes::rectangle(Rect::new(110.0, 10.0, 120.0, 20.0)), black);
+    hidden.visible = false;
+    let mut group = Node::group(d.alloc_id(), [shown, hidden].map(std::sync::Arc::new).to_vec());
+    let half = serde_json::json!({"scaleH": 50, "scaleV": 100});
+    group.appearance.effects.push(vectorcraft_doc::Effect { id: "distort.transform".into(), params: half, visible: true });
+    let l = d.layers[0].id;
+    d.insert(Some(l), 0, group).unwrap();
+    let b = art_bounds(&d).unwrap();
+    assert!(b.x0 <= 30.0 && b.x1 >= 80.0, "{b:?}");
+    let img = Renderer::new().render_region(&d, Rect::new(0.0, 0.0, 200.0, 100.0), 1.0, false);
+    let drawn = |x: u32| (0..100).any(|y| img.pixels[((y * 200 + x) * 4 + 3) as usize] > 0);
+    assert!(drawn(31) && drawn(78) && !drawn(28) && !drawn(82), "the rectangle is drawn from x 30 to x 80");
+}
+
 /// A black path round `r` in the first layer of `d`, made a guide when `guide`.
 fn add_rect(d: &mut Document, r: Rect, guide: bool) {
     let id = d.alloc_id();