Reorder initialization and rendering to prevent color flicker

scwx-qt/source/scwx/qt/map/color_table_layer.cpp

@@ -106,6 +106,12 @@ void ColorTableLayer::Render(const QMapbox::CustomLayerRenderParameters& params)
 {
    gl::OpenGLFunctions& gl = context()->gl_;
 
+   if (!context()->radarProductView_->IsInitialized())
+   {
+      // Defer rendering until view is initialized
+      return;
+   }
+
    glm::mat4 projection = glm::ortho(0.0f,
                                      static_cast<float>(params.width),
                                      0.0f,

scwx-qt/source/scwx/qt/map/map_widget.cpp

@@ -274,8 +274,6 @@ void MapWidget::SelectRadarProduct(common::Level2Product product)
    util::async(
       [=]()
       {
-         radarProductView->Initialize();
-
          std::string colorTableFile =
             manager::SettingsManager::palette_settings()->palette(
                common::GetLevel2Palette(product));
@@ -285,6 +283,8 @@ void MapWidget::SelectRadarProduct(common::Level2Product product)
                common::ColorTable::Load(colorTableFile);
             radarProductView->LoadColorTable(colorTable);
          }
+
+         radarProductView->Initialize();
       });
 
    if (p->map_ != nullptr)

scwx-qt/source/scwx/qt/view/level2_product_view.cpp

@@ -630,9 +630,9 @@ void Level2ProductView::ComputeSweep()
    BOOST_LOG_TRIVIAL(debug)
       << logPrefix_ << "Vertices calculated in " << timer.format(6, "%ws");
 
-   emit SweepComputed();
-
    UpdateColorTable();
+
+   emit SweepComputed();
 }
 
 std::shared_ptr<Level2ProductView> Level2ProductView::Create(

scwx-qt/source/scwx/qt/view/radar_product_view.cpp

@@ -24,9 +24,10 @@ static const uint16_t DEFAULT_COLOR_TABLE_MAX = 255u;
 class RadarProductViewImpl
 {
 public:
-   explicit RadarProductViewImpl() : sweepMutex_ {} {}
+   explicit RadarProductViewImpl() : initialized_ {false}, sweepMutex_ {} {}
    ~RadarProductViewImpl() = default;
 
+   bool       initialized_;
    std::mutex sweepMutex_;
 };
 
@@ -73,10 +74,17 @@ std::mutex& RadarProductView::sweep_mutex()
 void RadarProductView::Initialize()
 {
    ComputeSweep();
+
+   p->initialized_ = true;
 }
 
 void RadarProductView::SelectElevation(float elevation) {}
 
+bool RadarProductView::IsInitialized() const
+{
+   return p->initialized_;
+}
+
 std::vector<float> RadarProductView::GetElevationCuts() const
 {
    return {};

scwx-qt/source/scwx/qt/view/radar_product_view.hpp

@@ -45,6 +45,8 @@ public:
    virtual void SelectTime(std::chrono::system_clock::time_point time) = 0;
    virtual void Update()                                               = 0;
 
+   bool IsInitialized() const;
+
    virtual common::RadarProductGroup GetRadarProductGroup() const = 0;
    virtual std::string               GetRadarProductName() const  = 0;
    virtual std::vector<float>        GetElevationCuts() const;