Interface size in finer percent steps; fixed sizes no longer double the interface

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/settings.rs

@@ -148,7 +148,8 @@ pub struct Settings {
     pub outlines: bool,
     pub wall_detail: u8, // 1 low, 2 medium, 3 high
     pub max_lights: u8,  // 8, 16 or 24
-    pub ui_factor: u8,   // interface size: 0 = automatic, 2 large, 3 medium, 4 small (interface pixels per world pixel)
+    pub ui_factor: u8,   // old interface size (2 large, 3 medium, 4 small; only read to carry old settings over)
+    pub ui_size: u16,    // interface size in percent of the standard (100 = 1080 interface rows), 0 = automatic
     pub render_scale: u8, // old pixel-look divisor (no longer used, kept for old settings files)
     pub pixel_rows: u16,  // pixel look: rows of the world on every screen (270, 360, 480)
     pub touch_ui: u8,     // touch interface: 0 = automatic (after the first touch), 1 = on, 2 = off
@@ -189,6 +190,7 @@ impl Default for Settings {
             wall_detail: 2,
             max_lights: 24,
             ui_factor: 0,
+            ui_size: 0,
             render_scale: 1,
             pixel_rows: 360,
             touch_ui: 0,
@@ -244,10 +246,32 @@ impl Settings {
     }
 
     pub fn from_json(s: &str) -> Option<Settings> {
-        serde_json::from_str(s).ok()
+        let mut st: Settings = serde_json::from_str(s).ok()?;
+        // old interface sizes (pixels per world pixel) become percentages
+        if st.ui_size == 0 {
+            st.ui_size = match st.ui_factor {
+                2 => 150,
+                3 => 100,
+                4 => 75,
+                _ => 0,
+            };
+        }
+        st.ui_factor = 0;
+        if st.ui_size != 0 && !UI_SIZES.contains(&st.ui_size) {
+            st.ui_size = 0;
+        }
+        Some(st)
     }
 }
 
+// the interface sizes of the settings menu in percent (0 = automatic), from small to large
+pub const UI_SIZES: [u16; 9] = [0, 75, 85, 100, 115, 130, 150, 175, 200];
+
+// interface rows of the virtual screen for a size in percent (100% = 1080 rows)
+pub fn ui_size_rows(percent: u16) -> u32 {
+    (1080.0 * 100.0 / percent.max(1) as f32).round() as u32
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -273,4 +297,18 @@ mod tests {
         assert!(!old.debug_trigger_zones);
         assert!(!old.debug_command_markers);
     }
+
+    #[test]
+    fn interface_size_percent() {
+        let old = Settings::from_json(r#"{"ui_factor":2}"#).unwrap();
+        assert_eq!(old.ui_size, 150);
+        assert_eq!(old.ui_factor, 0);
+        let mut s = Settings::default();
+        s.ui_size = 115;
+        assert_eq!(Settings::from_json(&s.to_json()).unwrap().ui_size, 115);
+        assert_eq!(Settings::from_json(r#"{"ui_size":123}"#).unwrap().ui_size, 0);
+        assert_eq!(ui_size_rows(100), 1080);
+        assert_eq!(ui_size_rows(150), 720);
+        assert!(ui_size_rows(200) < ui_size_rows(175));
+    }
 }