tighten up the log level changing

src/frontend/mod.rs

@@ -221,29 +221,14 @@ impl App {
     }
 }
 
-fn change_log_level(delta: i8) {
-    let level = log::max_level();
-    use LevelFilter::*;
-    let nl = if delta.signum().is_positive() {
-        match level {
-            Off => Error,
-            Error => Warn,
-            Warn => Info,
-            Info => Debug,
-            Debug => Trace,
-            Trace => Trace,
-        }
-    } else {
-        match level {
-            Off => Off,
-            Error => Off,
-            Warn => Error,
-            Info => Warn,
-            Debug => Info,
-            Trace => Debug,
-        }
-    };
-    log::set_max_level(nl);
+fn change_log_level(delta: isize) {
+    let level = log::max_level() as isize;
+    let max = log::LevelFilter::max() as isize;
+    let level = (level + delta).clamp(0, max) as usize;
+    // levelfilter is repr(usize) so this is safe
+    let level = unsafe { std::mem::transmute::<usize, LevelFilter>(level) };
+
+    log::set_max_level(level);
 }
 
 impl Widget for &App {