Part of #3229: setting type in a font or style that isn't available warns

Squashed from #4866 onto main.

crates/engine/src/cmd/textedit.rs

@@ -39,7 +39,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Character",
             [],
             None,
-            "{id? (default: the one selected type object), start?: byte, end?: byte (default: all text), font?, style?, size?: pt, leading?: pt|\"auto\", tracking?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, fill?: colour|\"none\", stroke?: colour|\"none\", keepModel?: bool (fill and stroke, as paint.setFill), strokeWidth?: pt, strokeOptions?: {weight?, cap?, join?, miterLimit?, align?, dash?, dashOffset?, alignDashes?} (as stroke.set: the character stroke), underline?, strikethrough?, allCaps?: bool, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), features?: [\"dlig\", \"-liga\", …], charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\"|\"icfTop\"|\"icfBottom\", proportionalMetrics?: bool (full-width glyphs on the font's proportional widths: `palt` in horizontal type, `vpal` in vertical type), tateChuYoko?: bool (Character panel menu › Tate-chu-yoko, with Show East Asian Options: in vertical type those characters stand side by side across one em of the column; kept on the characters and ignored in horizontal type), noBreak?: bool (Character panel menu › No Break: these characters stay on one line, including across a space inside the run), charDirection?: \"default\"|\"leftToRight\"|\"rightToLeft\" (Character panel menu › Character Direction: the characters are set left to right or right to left inside their paragraph, as a Unicode bidi embedding; default: as the bidi algorithm sets them), digits?: \"default\"|\"arabic\"|\"hindi\"|\"farsi\" (Character panel menu › Digits: the numeral system every digit is drawn in, whatever was typed), fontAxes?: {\"wght\": 650, …} (Character panel › Variable Font: the setting of each variation axis named, in the axis's units and clamped to its range; null: back to the style's own setting; other axes keep theirs; tags the font has no axis for are left out; a font or style change clears them; text.fontList {family, style} lists the axes)} style a character range (size/leading/baselineShift are document points and hScale includes the object transform; runs are split at the range ends) → {id, runs}",
+            "{id? (default: the one selected type object), start?: byte, end?: byte (default: all text), font?, style?, size?: pt, leading?: pt|\"auto\", tracking?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, fill?: colour|\"none\", stroke?: colour|\"none\", keepModel?: bool (fill and stroke, as paint.setFill), strokeWidth?: pt, strokeOptions?: {weight?, cap?, join?, miterLimit?, align?, dash?, dashOffset?, alignDashes?} (as stroke.set: the character stroke), underline?, strikethrough?, allCaps?: bool, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), features?: [\"dlig\", \"-liga\", …], charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\"|\"icfTop\"|\"icfBottom\", proportionalMetrics?: bool (full-width glyphs on the font's proportional widths: `palt` in horizontal type, `vpal` in vertical type), tateChuYoko?: bool (Character panel menu › Tate-chu-yoko, with Show East Asian Options: in vertical type those characters stand side by side across one em of the column; kept on the characters and ignored in horizontal type), noBreak?: bool (Character panel menu › No Break: these characters stay on one line, including across a space inside the run), charDirection?: \"default\"|\"leftToRight\"|\"rightToLeft\" (Character panel menu › Character Direction: the characters are set left to right or right to left inside their paragraph, as a Unicode bidi embedding; default: as the bidi algorithm sets them), digits?: \"default\"|\"arabic\"|\"hindi\"|\"farsi\" (Character panel menu › Digits: the numeral system every digit is drawn in, whatever was typed), fontAxes?: {\"wght\": 650, …} (Character panel › Variable Font: the setting of each variation axis named, in the axis's units and clamped to its range; null: back to the style's own setting; other axes keep theirs; tags the font has no axis for are left out; a font or style change clears them; text.fontList {family, style} lists the axes)} style a character range (size/leading/baselineShift are document points and hScale includes the object transform; runs are split at the range ends) → {id, runs, warning?: text (the font or style set isn't available: its type is drawn in the fallback font or the family's closest style)}",
             has_doc,
             set_range_style
         ),
@@ -708,6 +708,9 @@ fn set_range_style(s: &mut Session, p: &Value) -> Result<Value> {
     let t = text_ref(s, id)?;
     change.localize(&t, C)?;
     let (a, b) = range_of(p, edit::runs_len(&t.runs), C)?;
+    // The fonts the styled characters are set in, for the warning.
+    let mut set = std::collections::BTreeSet::new();
+    let sets_font = change.font.is_some() || change.style.is_some();
     let n = s.edit("Character", |d, _| {
         let t = text_mut(d, id).ok_or(EngineError::NoNode(id))?;
         if a == b && !t.plain_text().is_empty() {
@@ -719,10 +722,19 @@ fn set_range_style(s: &mut Session, p: &Value) -> Result<Value> {
         if let Some(before) = before {
             protect_missing_glyphs(&before, &mut t.runs);
         }
+        if sets_font {
+            // Empty text has one run, which the empty range styles.
+            let styled = if a == b { t.runs.clone() } else { edit::slice_runs(&t.runs, a, b) };
+            set.extend(styled.iter().map(|r| super::fonts::font_of(&r.style)));
+        }
         refresh_bounds(t);
         Ok(t.runs.len())
     })?;
-    Ok(json!({"id": id.0, "runs": n}))
+    let mut out = json!({"id": id.0, "runs": n});
+    if let Some(w) = super::fonts::set_font_warning(set) {
+        out["warning"] = json!(w);
+    }
+    Ok(out)
 }
 
 /// The em a laid-out glyph's kerning and tracking are measured in, in text space: the size it