UI: simplify ui_draw_vision_speed (#19594)

* simplify draw_vision_speed

* use std::nearbyint

* use std::to_string
old-commit-hash: ba4fb80e92

selfdrive/ui/paint.cc

@@ -325,23 +325,11 @@ static void ui_draw_vision_maxspeed(UIState *s) {
 }
 
 static void ui_draw_vision_speed(UIState *s) {
-  const Rect &viz_rect = s->scene.viz_rect;
-  float v_ego = s->scene.controls_state.getVEgo();
-  float speed = v_ego * 2.2369363 + 0.5;
-  if (s->is_metric){
-    speed = v_ego * 3.6 + 0.5;
-  }
-  const int viz_speed_w = 280;
-  const int viz_speed_x = viz_rect.centerX() - viz_speed_w/2;
-  char speed_str[32];
-
-  nvgBeginPath(s->vg);
-  nvgRect(s->vg, viz_speed_x, viz_rect.y, viz_speed_w, header_h);
+  const float speed = s->scene.controls_state.getVEgo() * (s->is_metric ? 3.6 : 2.2369363);
+  const std::string speed_str = std::to_string((int)std::nearbyint(speed));
   nvgTextAlign(s->vg, NVG_ALIGN_CENTER | NVG_ALIGN_BASELINE);
-
-  snprintf(speed_str, sizeof(speed_str), "%d", (int)speed);
-  ui_draw_text(s->vg, viz_rect.centerX(), 240, speed_str, 96*2.5, COLOR_WHITE, s->font_sans_bold);
-  ui_draw_text(s->vg, viz_rect.centerX(), 320, s->is_metric?"km/h":"mph", 36*2.5, COLOR_WHITE_ALPHA(200), s->font_sans_regular);
+  ui_draw_text(s->vg, s->scene.viz_rect.centerX(), 240, speed_str.c_str(), 96 * 2.5, COLOR_WHITE, s->font_sans_bold);
+  ui_draw_text(s->vg, s->scene.viz_rect.centerX(), 320, s->is_metric ? "km/h" : "mph", 36 * 2.5, COLOR_WHITE_ALPHA(200), s->font_sans_regular);
 }
 
 static void ui_draw_vision_event(UIState *s) {