feat: make image loading async

tests/jobs_tests.cpp

@@ -5,7 +5,9 @@
 #include <stdexcept>
 #include <thread>
 #include <vector>
+#include <cstring>
 
+#include <destrum/Graphics/imageLoader.h>
 #include <destrum/Serialization/SceneSerializer.h>
 #include <destrum/Threading/JobSystem.h>
 
@@ -161,6 +163,47 @@ namespace {
         Jobs().Shutdown();
     }
 
+    void testAsyncHighPriority()
+    {
+        Jobs().Init(2);
+        auto future = Jobs().Async([] { return std::this_thread::get_id(); }, JobPriority::High);
+        check(future.get() != std::this_thread::get_id(), "high priority Async should run on a worker");
+        Jobs().Shutdown();
+    }
+
+    void testImageDecodeOnWorkersMatchesSerial()
+    {
+        const std::filesystem::path root = DESTRUM_ENGINE_ASSETS_SRC_DIR;
+        const std::vector<std::filesystem::path> paths{
+            root / "238882.png",
+            root / "char.jpg",
+            root / "flight-helmet" / "FlightHelmet_Materials_GlassPlasticMat_Normal.png",
+            root / "does_not_exist.png",
+        };
+
+        Jobs().Init(4);
+        std::vector<std::future<ImageData>> decoded;
+        for (const auto& path : paths) {
+            decoded.push_back(Jobs().Async([path] { return util::loadImage(path, TextureIntent::ColorSrgb); },
+                                           JobPriority::High));
+        }
+
+        for (std::size_t i = 0; i < paths.size(); ++i) {
+            const ImageData parallel = decoded[i].get();
+            const ImageData serial = util::loadImage(paths[i], TextureIntent::ColorSrgb);
+            check(parallel.vkFormat == serial.vkFormat && parallel.width == serial.width &&
+                  parallel.height == serial.height && parallel.byteSize == serial.byteSize,
+                  "decoding on a worker should give the same image layout");
+            if (serial.pixels != nullptr) {
+                check(parallel.pixels != nullptr &&
+                      std::memcmp(parallel.pixels, serial.pixels, serial.byteSize) == 0,
+                      "decoding on a worker should give the same pixels");
+            }
+        }
+        check(decoded.size() == 4, "every image should be decoded");
+        Jobs().Shutdown();
+    }
+
     void testRunsInlineWhenStopped()
     {
         check(!Jobs().IsRunning(), "job system should start stopped");
@@ -183,4 +226,6 @@ void RunJobsTests()
     testMainThreadQueue();
     testShutdownDrainsPendingJobs();
     testLoadSceneFileAsync();
+    testAsyncHighPriority();
+    testImageDecodeOnWorkersMatchesSerial();
 }