ui onroad: utilize local variables for repeated capnp reader access (#29325)

old-commit-hash: 22cf5421d6

selfdrive/ui/qt/onroad.cc

@@ -270,6 +270,8 @@ void AnnotatedCameraWidget::updateState(const UIState &s) {
   const bool nav_alive = sm.alive("navInstruction") && sm["navInstruction"].getValid();
 
   const auto cs = sm["controlsState"].getControlsState();
+  const auto car_state = sm["carState"].getCarState();
+  const auto nav_instruction = sm["navInstruction"].getNavInstruction();
 
   // Handle older routes where vCruiseCluster is not set
   float v_cruise =  cs.getVCruiseCluster() == 0.0 ? cs.getVCruise() : cs.getVCruiseCluster();
@@ -281,17 +283,17 @@ void AnnotatedCameraWidget::updateState(const UIState &s) {
 
   // Handle older routes where vEgoCluster is not set
   float v_ego;
-  if (sm["carState"].getCarState().getVEgoCluster() == 0.0 && !v_ego_cluster_seen) {
+  if (car_state.getVEgoCluster() == 0.0 && !v_ego_cluster_seen) {
-    v_ego = sm["carState"].getCarState().getVEgo();
+    v_ego = car_state.getVEgo();
   } else {
-    v_ego = sm["carState"].getCarState().getVEgoCluster();
+    v_ego = car_state.getVEgoCluster();
     v_ego_cluster_seen = true;
   }
   float cur_speed = cs_alive ? std::max<float>(0.0, v_ego) : 0.0;
   cur_speed *= s.scene.is_metric ? MS_TO_KPH : MS_TO_MPH;
 
-  auto speed_limit_sign = sm["navInstruction"].getNavInstruction().getSpeedLimitSign();
+  auto speed_limit_sign = nav_instruction.getSpeedLimitSign();
-  float speed_limit = nav_alive ? sm["navInstruction"].getNavInstruction().getSpeedLimit() : 0.0;
+  float speed_limit = nav_alive ? nav_instruction.getSpeedLimit() : 0.0;
   speed_limit *= (s.scene.is_metric ? MS_TO_KPH : MS_TO_MPH);
 
   setProperty("speedLimit", speed_limit);