M7: per-paragraph paragraph attributes

Each paragraph has its own alignment, indents, spacing, hyphenation, tab
stops and paragraph style (TextObject.paras; para stays paragraph 0's, so
old files and readers work). Layout, editing (split/merge), threads, the
Paragraph/Tabs/Paragraph Styles panels, ranged text.setStyle/setFormat/
tabs/paraStyle.apply, SVG export/import and the fuzzers follow.

crates/engine/src/cmd/textstyles.rs

@@ -66,7 +66,7 @@ macro_rules! style_cmds {
                 concat!($p, ".apply"),
                 concat!("Apply ", $what, " Style"),
                 &[],
-                "{name, clearOverrides?, ids?|id + start?/end? (a Type tool range)} → {count}",
+                "{name, clearOverrides?, ids?|id + start?/end? (a Type tool range: character styles style it, paragraph styles apply to the paragraphs it touches)} → {count}",
                 |s, p| apply(s, p, $kind),
                 true,
             ),
@@ -179,7 +179,7 @@ fn text_mut(d: &mut Document, id: NodeId) -> Option<&mut vectorcraft_doc::TextOb
     }
 }
 
-/// How many runs (char) or text objects (para) use `name`.
+/// How many runs (char) or paragraphs (para) use `name`.
 fn uses(d: &Document, kind: Kind, name: &str) -> usize {
     let target = (name != kind.normal()).then_some(name);
     let mut n = 0;
@@ -187,7 +187,7 @@ fn uses(d: &Document, kind: Kind, name: &str) -> usize {
         if let NodeKind::Text(t) = &node.kind {
             n += match kind {
                 Kind::Char => t.runs.iter().filter(|r| r.style.style_name.as_deref() == target).count(),
-                Kind::Para => usize::from(t.para.style_name.as_deref() == target),
+                Kind::Para => (0..t.paragraph_count()).filter(|&i| t.para_at(i).style_name.as_deref() == target).count(),
             };
         }
     });
@@ -210,9 +210,11 @@ fn update_users(d: &mut Document, kind: Kind, name: &str, old: &Map<String, Valu
                 }
             }
             Kind::Para => {
-                if t.para.style_name == target {
-                    t.para = restyle(&t.para, old, new);
-                    changed = true;
+                for pa in t.para_styles_mut() {
+                    if pa.style_name == target {
+                        *pa = restyle(pa, old, new);
+                        changed = true;
+                    }
                 }
             }
         }
@@ -231,12 +233,11 @@ fn selection_attrs(s: &Session, p: &Value, kind: Kind) -> Result<Option<Map<Stri
         None => text_targets(s, &json!({}), "").ok().and_then(|v| v.first().copied()),
     };
     let Some(NodeKind::Text(t)) = id.and_then(|i| d.node(i)).map(|n| &n.kind) else { return Ok(None) };
+    let at = p.get("start").and_then(Value::as_u64).map_or(0, |v| usize::try_from(v).unwrap_or(usize::MAX));
     Ok(Some(match kind {
-        Kind::Char => {
-            let at = p.get("start").and_then(Value::as_u64).unwrap_or(0) as usize;
-            to_attrs(&vectorcraft_text::edit::style_at(&t.runs, at))
-        }
-        Kind::Para => to_attrs(&t.para),
+        Kind::Char => to_attrs(&vectorcraft_text::edit::style_at(&t.runs, at)),
+        // The paragraph at `start`.
+        Kind::Para => to_attrs(t.para_at(t.paragraphs_in(at, at).start)),
     }))
 }
 
@@ -329,8 +330,9 @@ fn apply(s: &mut Session, p: &Value, kind: Kind) -> Result<Value> {
     let normal = kind.attrs(d, kind.normal()).unwrap_or_default();
     let clear = bool_or(p, "clearOverrides", false);
     let style_name = (name != kind.normal()).then(|| name.clone());
-    // A Type tool range (character styles only) or whole text objects.
-    let range = id_param(p, "id").filter(|_| kind == Kind::Char && (p.get("start").is_some() || p.get("end").is_some()));
+    // A Type tool range or whole text objects.
+    let text_range = super::typecmd::TextRange::parse(p, &c)?;
+    let range = id_param(p, "id").filter(|_| text_range.is_some());
     let ids = match range.or_else(|| id_param(p, "id")) {
         Some(id) => vec![id],
         None => text_targets(s, p, &c)?,
@@ -376,7 +378,17 @@ fn apply(s: &mut Session, p: &Value, kind: Kind) -> Result<Value> {
                         return Err(e);
                     }
                 }
-                Kind::Para => t.para = para_fn(&t.para)?,
+                Kind::Para => {
+                    let mut v = t.paragraph_styles();
+                    let span = match (range, text_range) {
+                        (Some(_), Some(r)) => r.paras(t),
+                        _ => 0..v.len(),
+                    };
+                    for st in v.iter_mut().take(span.end).skip(span.start) {
+                        *st = para_fn(st)?;
+                    }
+                    t.set_paragraph_styles(v);
+                }
             }
             refresh_bounds(t);
         }
@@ -447,7 +459,7 @@ fn rename(s: &mut Session, p: &Value, kind: Kind) -> Result<Value> {
             };
             match kind {
                 Kind::Char => t.runs.iter_mut().for_each(|r| fix(&mut r.style.style_name)),
-                Kind::Para => fix(&mut t.para.style_name),
+                Kind::Para => t.para_styles_mut().for_each(|pa| fix(&mut pa.style_name)),
             }
         }
         Ok(())
@@ -472,7 +484,7 @@ fn delete(s: &mut Session, p: &Value, kind: Kind) -> Result<Value> {
             };
             match kind {
                 Kind::Char => t.runs.iter_mut().for_each(|r| fix(&mut r.style.style_name)),
-                Kind::Para => fix(&mut t.para.style_name),
+                Kind::Para => t.para_styles_mut().for_each(|pa| fix(&mut pa.style_name)),
             }
         }
         Ok(())