perf counter for render

time/src/perf.rs

@@ -34,6 +34,17 @@ impl PerfModel {
             None
         }
     }
+    pub fn get_t1 (&self, t0: Option<u64>) -> Option<std::time::Duration> {
+        if let Some(t0) = t0 {
+            if self.enabled {
+                Some(self.clock.delta(t0, self.clock.raw()))
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
     pub fn update (&self, t0: Option<u64>, scope: &ProcessScope) {
         if let Some(t0) = t0 {
             let t1 = self.clock.raw();