limit icon flickering in UI (#21132)

selfdrive/ui/paint.cc

@@ -211,7 +211,7 @@ static void ui_draw_vision_speed(UIState *s) {
 }
 
 static void ui_draw_vision_event(UIState *s) {
-  if ((*s->sm)["controlsState"].getControlsState().getEngageable()) {
+  if (s->scene.engageable) {
     // draw steering wheel
     const int radius = 96;
     const int center_x = s->viz_rect.right() - radius - bdr_s * 2;
@@ -226,8 +226,7 @@ static void ui_draw_vision_face(UIState *s) {
   const int radius = 96;
   const int center_x = s->viz_rect.x + radius + (bdr_s * 2);
   const int center_y = s->viz_rect.bottom() - footer_h / 2;
-  bool is_active = (*s->sm)["driverMonitoringState"].getDriverMonitoringState().getIsActiveMode();
+  ui_draw_circle_image(s, center_x, center_y, radius, "driver_face", s->scene.dm_active);
-  ui_draw_circle_image(s, center_x, center_y, radius, "driver_face", is_active);
 }
 
 static void ui_draw_vision_header(UIState *s) {

selfdrive/ui/ui.cc

@@ -129,6 +129,11 @@ static void update_state(UIState *s) {
   SubMaster &sm = *(s->sm);
   UIScene &scene = s->scene;
 
+  // update engageability and DM icons at 2Hz
+  if (sm.frame % (UI_FREQ / 2) == 0) {
+    scene.engageable = sm["controlsState"].getControlsState().getEngageable();
+    scene.dm_active = sm["driverMonitoringState"].getDriverMonitoringState().getIsActiveMode();
+  }
   if (sm.updated("radarState")) {
     std::optional<cereal::ModelDataV2::XYZTData::Reader> line;
     if (sm.rcv_frame("modelV2") > 0) {

selfdrive/ui/ui.h

@@ -94,6 +94,8 @@ typedef struct UIScene {
   line_vertices_data lane_line_vertices[4];
   line_vertices_data road_edge_vertices[2];
 
+  bool dm_active, engageable;
+
   // lead
   vertex_data lead_vertices[2];