Add formatters for percentages

plugins/diopser/src/lib.rs

@@ -211,7 +211,8 @@ impl DiopserParams {
                 FloatRange::Linear { min: 0.0, max: 1.0 },
             )
             .with_unit("%")
-            .with_value_to_string(Arc::new(|value| format!("{:.0}", value * 100.0))),
+            .with_value_to_string(formatters::f32_percentage(0))
+            .with_string_to_value(formatters::from_f32_percentage()),
         }
     }
 }

src/formatters.rs

@@ -7,6 +7,24 @@ pub fn f32_rounded(digits: usize) -> Arc<dyn Fn(f32) -> String + Send + Sync> {
     Arc::new(move |x| format!("{:.digits$}", x))
 }
 
+/// Format a `[0, 1]` number as a percentage. Does not include the percent sign, you should specify
+/// this as the parameter's unit.
+pub fn f32_percentage(digits: usize) -> Arc<dyn Fn(f32) -> String + Send + Sync> {
+    Arc::new(move |value| format!("{:.digits$}", value * 100.0))
+}
+
+/// Parse a `[0, 100]` percentage to a `[0, 1]` number. Handles the percentage unit for you. Used in
+/// conjunction with [`f32_percentage`].
+pub fn from_f32_percentage() -> Arc<dyn Fn(&str) -> Option<f32> + Send + Sync> {
+    Arc::new(|string| {
+        string
+            .trim_end_matches(&[' ', '%'])
+            .parse()
+            .ok()
+            .map(|x: f32| x / 100.0)
+    })
+}
+
 /// Format an order/power of two. Useful in conjunction with [`from_power_of_two()`] to limit
 /// integer parameter ranges to be only powers of two.
 pub fn i32_power_of_two() -> Arc<dyn Fn(i32) -> String + Send + Sync> {