feat: Support for building ImHex for the web (#1328)

Co-authored-by: WerWolv <werwolv98@gmail.com>
Co-authored-by: AnnsAnn <git@annsann.eu>

main/gui/source/main.cpp

@@ -19,6 +19,11 @@
 #include <wolv/io/fs.hpp>
 #include <wolv/utils/guards.hpp>
 
+#if defined(OS_WEB)
+    #include <emscripten.h>
+    #include <emscripten/html5.h>
+#endif
+
 using namespace hex;
 
 namespace {
@@ -66,6 +71,7 @@ namespace {
     /**
      * @brief Displays ImHex's splash screen and runs all initialization tasks. The splash screen will be displayed until all tasks have finished.
      */
+    [[maybe_unused]]
     void initializeImHex() {
         init::WindowSplash splashWindow;
 
@@ -105,6 +111,103 @@ namespace {
         }
     }
 
+
+    #if defined(OS_WEB)
+        using namespace hex::init;
+
+        void saveFsData() {
+            EM_ASM({
+                FS.syncfs(function (err) {
+                    if (!err)
+                        return;
+                    alert("Failed to save permanent file system: "+err);
+                });
+            });
+        }
+
+        int runImHex() {
+            auto splashWindow = new WindowSplash();
+
+            log::info("Using '{}' GPU", ImHexApi::System::getGPUVendor());
+
+            // Add initialization tasks to run
+            TaskManager::init();
+            for (const auto &[name, task, async] : init::getInitTasks())
+                splashWindow->addStartupTask(name, task, async);
+
+            splashWindow->startStartupTasks();
+
+            // Draw the splash window while tasks are running
+            emscripten_set_main_loop_arg([](void *arg) {
+                auto splashWindow = reinterpret_cast<WindowSplash*>(arg);
+
+                FrameResult res = splashWindow->fullFrame();
+                if (res == FrameResult::success) {
+                    handleFileOpenRequest();
+
+                    // Clean up everything after the main window is closed
+                    emscripten_set_beforeunload_callback(nullptr, [](int eventType, const void *reserved, void *userData) {
+                        hex::unused(eventType, reserved, userData);
+
+                        try {
+                            saveFsData();
+                            deinitializeImHex();
+                            return "";
+                        } catch (const std::exception &ex) {
+                            std::string *msg = new std::string("Failed to deinitialize ImHex. This is just a message warning you of this, the application has already closed, you probably can't do anything about it. Message: ");
+                            msg->append(std::string(ex.what()));
+                            log::fatal("{}", *msg);
+                            return msg->c_str();
+                        }
+                    });
+
+                    // Delete splash window (do it before creating the main window so glfw destroys the window)
+                    delete splashWindow;
+
+                    emscripten_cancel_main_loop();
+
+                    // Main window
+                    static Window window;
+                    emscripten_set_main_loop([]() {
+                        window.fullFrame();
+                    }, 60, 0);
+                }
+            }, splashWindow, 60, 0);
+
+            return -1;
+        }
+
+    #else
+
+        int runImHex() {
+
+            bool shouldRestart = false;
+            do {
+                // Register an event handler that will make ImHex restart when requested
+                shouldRestart = false;
+                EventManager::subscribe<RequestRestartImHex>([&] {
+                    shouldRestart = true;
+                });
+
+                initializeImHex();
+                handleFileOpenRequest();
+
+                // Clean up everything after the main window is closed
+                ON_SCOPE_EXIT {
+                    deinitializeImHex();
+                };
+
+                // Main window
+                Window window;
+                window.loop();
+
+            } while (shouldRestart);
+
+            return EXIT_SUCCESS;
+        }
+
+    #endif
+
 }
 
 /**
@@ -127,27 +230,5 @@ int main(int argc, char **argv) {
 
     ImHexApi::System::impl::setPortableVersion(isPortableVersion());
 
-    bool shouldRestart = false;
-    do {
-        // Register an event handler that will make ImHex restart when requested
-        shouldRestart = false;
-        EventManager::subscribe<RequestRestartImHex>([&] {
-            shouldRestart = true;
-        });
-
-        initializeImHex();
-        handleFileOpenRequest();
-
-        // Clean up everything after the main window is closed
-        ON_SCOPE_EXIT {
-            deinitializeImHex();
-        };
-
-        // Main window
-        Window window;
-        window.loop();
-
-    } while (shouldRestart);
-
-    return EXIT_SUCCESS;
-}
+    return runImHex();
+};