M7: area type auto size and shrink text to fit

Area Type Options gain a fit: none, autoHeight (Illustrator's Auto Size:
the frame's height follows the text after every edit, resolved in
refresh_bounds inside the edit so it shares the edit's undo step) and
shrinkText {minPercent} (beyond Illustrator: overflowing text scales its
sizes, leading and baseline shifts down at layout time by the largest
factor, in 0.1 pt steps of the first run, that fits). The Auto Size New
Area Type preference now applies. text.areaOptions and document.inspect
report overflow and the shrink factor; the Area Type Options dialog
offers fit and first baseline as dropdowns.

crates/doc/src/lib.rs

@@ -82,8 +82,9 @@ pub use setup::{Background, DocSetup, ExportText, GridSize, Quotes};
 pub use slices::{CellAlign, CellVAlign, Slice, SliceArea, SliceKind, SliceOptions, SliceSource};
 pub use style_libs::StyleLibrary;
 pub use text::{
-    AreaOptions, Burasagari, CharAlign, CharPosition, CharStyle, Composer, FirstBaseline, Justify, LeadingModel, Mojikumi, ParaDirection, ParaStyle,
-    PathAlign, PathEffect, ScriptMetrics, TabAlign, TabStop, TextKind, TextObject, TextRun, TextStyleDef, TextWrap, VerticalAlign, WrapShape,
+    AreaFit, AreaOptions, Burasagari, CharAlign, CharPosition, CharStyle, Composer, FirstBaseline, Justify, LeadingModel, Mojikumi, ParaDirection,
+    ParaStyle, PathAlign, PathEffect, ScriptMetrics, TabAlign, TabStop, TextKind, TextObject, TextRun, TextStyleDef, TextWrap, VerticalAlign,
+    WrapShape,
 };
 pub use vectorcraft_color as color;
 pub use vectorcraft_geom as geom;

crates/doc/src/text.rs

@@ -664,6 +664,9 @@ pub struct AreaOptions {
     pub first_baseline_min: f64,
     /// Vertical alignment of the lines in each row/column.
     pub vertical_align: VerticalAlign,
+    /// How the frame and its text fit each other (Auto Size, Shrink Text to Fit).
+    #[serde(skip_serializing_if = "crate::skip::is_default")]
+    pub fit: AreaFit,
 }
 
 impl Default for AreaOptions {
@@ -676,6 +679,67 @@ impl Default for AreaOptions {
             first_baseline: FirstBaseline::Ascent,
             first_baseline_min: 0.0,
             vertical_align: VerticalAlign::Top,
+            fit: AreaFit::None,
+        }
+    }
+}
+
+/// How area type and its frame fit each other. Serialized as `"none"`, `"autoHeight"` or
+/// `{"shrinkText": {"minPercent": 50}}`.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum AreaFit {
+    /// The frame keeps its size; text that doesn't fit overflows.
+    #[default]
+    None,
+    /// The frame's height follows the text (Illustrator's Auto Size): resolved by the engine after
+    /// each edit, for rectangular frames of horizontal type in one row.
+    AutoHeight,
+    /// Text that overflows is scaled down (size, leading and baseline shift; not paragraph
+    /// spacing) by the largest factor down to `min_percent` % that makes it fit, at layout time.
+    ShrinkText {
+        #[serde(rename = "minPercent", default = "AreaFit::default_min_percent")]
+        min_percent: f64,
+    },
+}
+
+impl AreaFit {
+    /// The smallest Shrink Text to Fit percentage allowed.
+    pub const MIN_PERCENT: f64 = 10.0;
+    /// The Shrink Text to Fit percentage new settings start with.
+    pub const DEFAULT_MIN_PERCENT: f64 = 50.0;
+    fn default_min_percent() -> f64 {
+        Self::DEFAULT_MIN_PERCENT
+    }
+    /// Its id: `none`, `autoHeight` or `shrinkText`.
+    pub fn id(self) -> &'static str {
+        match self {
+            AreaFit::None => "none",
+            AreaFit::AutoHeight => "autoHeight",
+            AreaFit::ShrinkText { .. } => "shrinkText",
+        }
+    }
+    /// The fit an id names (case, spaces, dashes and underscores ignored), with `min_percent`
+    /// for Shrink Text (clamped to 10..100; a non-finite value gives the default).
+    pub fn parse(id: &str, min_percent: Option<f64>) -> Option<Self> {
+        match id.to_ascii_lowercase().replace([' ', '-', '_'], "").as_str() {
+            "none" | "off" => Some(AreaFit::None),
+            "autoheight" | "autosize" => Some(AreaFit::AutoHeight),
+            "shrinktext" | "shrinktexttofit" | "shrink" => {
+                Some(AreaFit::ShrinkText { min_percent: Self::clamp_percent(min_percent.unwrap_or(Self::DEFAULT_MIN_PERCENT)) })
+            }
+            _ => None,
+        }
+    }
+    /// A Shrink Text minimum percentage within 10..100 (the default when not finite).
+    pub fn clamp_percent(p: f64) -> f64 {
+        if p.is_finite() { p.clamp(Self::MIN_PERCENT, 100.0) } else { Self::DEFAULT_MIN_PERCENT }
+    }
+    /// Shrink Text's minimum scale factor (0.1..1), if this is Shrink Text.
+    pub fn min_scale(self) -> Option<f64> {
+        match self {
+            AreaFit::ShrinkText { min_percent } => Some(Self::clamp_percent(min_percent) / 100.0),
+            _ => None,
         }
     }
 }