Populate cached images into the texture atlas

scwx-qt/source/scwx/qt/gl/draw/geo_line.cpp

@@ -27,6 +27,8 @@ static constexpr size_t kPointsPerVertex      = 10;
 static constexpr size_t kBufferLength =
    kNumTriangles * kVerticesPerTriangle * kPointsPerVertex;
 
+static const std::string kTextureName = "lines/default-1x7";
+
 class GeoLine::Impl
 {
 public:
@@ -115,7 +117,7 @@ void GeoLine::Initialize()
    }
 
    p->texture_ =
-      util::TextureAtlas::Instance().GetTextureAttributes("lines/default-1x7");
+      util::TextureAtlas::Instance().GetTextureAttributes(kTextureName);
 
    gl.glGenVertexArrays(1, &p->vao_);
    gl.glGenBuffers(1, &p->vbo_);
@@ -248,6 +250,9 @@ void GeoLine::Impl::Update()
    {
       gl::OpenGLFunctions& gl = context_->gl();
 
+      texture_ =
+         util::TextureAtlas::Instance().GetTextureAttributes(kTextureName);
+
       // Latitude and longitude coordinates in degrees
       const float lx = points_[0].latitude_;
       const float rx = points_[1].latitude_;

scwx-qt/source/scwx/qt/manager/placefile_manager.cpp

@@ -459,14 +459,23 @@ void PlacefileManager::Impl::LoadResources(
    const QUrl baseUrl =
       QUrl::fromUserInput(QString::fromStdString(placefile->name()));
 
-   // TODO: Parallelize
+   std::vector<std::string> urlStrings;
-   for (auto& iconFile : iconFiles)
+   urlStrings.reserve(iconFiles.size());
-   {
-      QUrl fileUrl     = QUrl(QString::fromStdString(iconFile->filename_));
-      QUrl resolvedUrl = baseUrl.resolved(fileUrl);
 
-      ResourceManager::LoadImageResource(resolvedUrl.toString().toStdString());
+   std::transform(iconFiles.cbegin(),
-   }
+                  iconFiles.cend(),
+                  std::back_inserter(urlStrings),
+                  [&baseUrl](auto& iconFile)
+                  {
+                     // Resolve target URL relative to base URL
+                     QUrl fileUrl =
+                        QUrl(QString::fromStdString(iconFile->filename_));
+                     QUrl resolvedUrl = baseUrl.resolved(fileUrl);
+
+                     return resolvedUrl.toString().toStdString();
+                  });
+
+   ResourceManager::LoadImageResources(urlStrings);
 }
 
 } // namespace manager

scwx-qt/source/scwx/qt/manager/resource_manager.cpp

@@ -5,6 +5,9 @@
 #include <scwx/qt/util/texture_atlas.hpp>
 #include <scwx/util/logger.hpp>
 
+#include <execution>
+#include <mutex>
+
 #include <QFontDatabase>
 #include <imgui.h>
 
@@ -61,10 +64,36 @@ std::shared_ptr<util::Font> Font(types::Font font)
    return nullptr;
 }
 
-void LoadImageResource(const std::string& urlString)
+bool LoadImageResource(const std::string& urlString)
 {
    util::TextureAtlas& textureAtlas = util::TextureAtlas::Instance();
-   textureAtlas.CacheTexture(urlString, urlString);
+   return textureAtlas.CacheTexture(urlString, urlString);
+}
+
+void LoadImageResources(const std::vector<std::string>& urlStrings)
+{
+   std::mutex m {};
+   bool       textureCached = false;
+
+   std::for_each(std::execution::par_unseq,
+                 urlStrings.begin(),
+                 urlStrings.end(),
+                 [&](auto& urlString)
+                 {
+                    bool value = LoadImageResource(urlString);
+
+                    if (value)
+                    {
+                       std::unique_lock lock {m};
+                       textureCached = true;
+                    }
+                 });
+
+   if (textureCached)
+   {
+      util::TextureAtlas& textureAtlas = util::TextureAtlas::Instance();
+      textureAtlas.BuildAtlas(1024, 1024);
+   }
 }
 
 static void LoadFonts()
@@ -90,7 +119,7 @@ static void LoadTextures()
                                 ":/res/textures/lines/default-1x7.png");
    textureAtlas.RegisterTexture("lines/test-pattern",
                                 ":/res/textures/lines/test-pattern.png");
-   textureAtlas.BuildAtlas(8, 8);
+   textureAtlas.BuildAtlas(1024, 1024);
 }
 
 } // namespace ResourceManager

scwx-qt/source/scwx/qt/manager/resource_manager.hpp

@@ -18,7 +18,8 @@ void Shutdown();
 int                         FontId(types::Font font);
 std::shared_ptr<util::Font> Font(types::Font font);
 
-void LoadImageResource(const std::string& urlString);
+bool LoadImageResource(const std::string& urlString);
+void LoadImageResources(const std::vector<std::string>& urlStrings);
 
 } // namespace ResourceManager
 } // namespace manager

scwx-qt/source/scwx/qt/util/texture_atlas.cpp

@@ -5,6 +5,7 @@
 
 #include <shared_mutex>
 #include <unordered_map>
+#include <variant>
 
 #if defined(_MSC_VER)
 #   pragma warning(push, 0)
@@ -111,8 +112,11 @@ void TextureAtlas::BuildAtlas(size_t width, size_t height)
       return;
    }
 
-   std::vector<std::pair<std::string, boost::gil::rgba8_image_t>> images;
+   std::vector<std::pair<
-   std::vector<stbrp_rect>                                        stbrpRects;
+      std::string,
+      std::variant<boost::gil::rgba8_image_t, boost::gil::rgba8_image_t*>>>
+                           images;
+   std::vector<stbrp_rect> stbrpRects;
 
    // Load images
    {
@@ -145,9 +149,33 @@ void TextureAtlas::BuildAtlas(size_t width, size_t height)
                     });
    }
 
-   // TODO: Cached images
+   // Cached images
-   {
 
+   // Take a read lock on the texture cache map. The read lock must persist
+   // through atlas population, as a pointer to the image is taken and used.
+   std::shared_lock textureCacheLock(p->textureCacheMutex_);
+
+   {
+      // For each cached texture
+      for (auto& texture : p->textureCache_)
+      {
+         auto& image = texture.second;
+
+         if (image.width() > 0u && image.height() > 0u)
+         {
+            // Store STB rectangle pack data in a vector
+            stbrpRects.push_back(
+               stbrp_rect {0,
+                           static_cast<stbrp_coord>(image.width()),
+                           static_cast<stbrp_coord>(image.height()),
+                           0,
+                           0,
+                           0});
+
+            // Store image data in a vector
+            images.emplace_back(texture.first, &image);
+         }
+      }
    }
 
    // Pack images
@@ -195,8 +223,22 @@ void TextureAtlas::BuildAtlas(size_t width, size_t height)
       if (stbrpRects[i].was_packed != 0)
       {
          // Populate the atlas
-         boost::gil::rgba8c_view_t imageView =
+         boost::gil::rgba8c_view_t imageView;
-            boost::gil::const_view(images[i].second);
+
+         // Retrieve the image
+         if (std::holds_alternative<boost::gil::rgba8_image_t>(
+                images[i].second))
+         {
+            imageView = boost::gil::const_view(
+               std::get<boost::gil::rgba8_image_t>(images[i].second));
+         }
+         else if (std::holds_alternative<boost::gil::rgba8_image_t*>(
+                     images[i].second))
+         {
+            imageView = boost::gil::const_view(
+               *std::get<boost::gil::rgba8_image_t*>(images[i].second));
+         }
+
          boost::gil::rgba8_view_t atlasSubView =
             boost::gil::subimage_view(atlasView,
                                       stbrpRects[i].x,