Add an ability to preload a sound file without decoding

PR #2006 effectively reverted the behavior of preloaded sounds
to state from before #431, bringing back old memory consumption
issues. For games that want to download all their assets during
the loading screen, but don't want to actually decode all sounds
right away because of memory consumption concerns, being able to
dynamically load/unload Howler objects via events is not enough,
as the application may already go out-of-memory during loading,
and not doing that will cause the game to download additional
assets during gameplay. This change adds a new property,
"preloadAsFile", which makes GDJS request the sound asset via XHR.
This puts the file into browser cache, so it can be reasonably
expected to be decoded later without issuing network requests.

Author: dos1

Core/GDCore/Project/ResourcesManager.cpp

@@ -189,6 +189,9 @@ std::map<gd::String, gd::PropertyDescriptor> AudioResource::GetProperties()
   properties[_("Preload as music")]
       .SetValue(preloadAsMusic ? "true" : "false")
       .SetType("Boolean");
+  properties[_("Preload as file")]
+      .SetValue(preloadAsFile ? "true" : "false")
+      .SetType("Boolean");
 
   return properties;
 }
@@ -199,6 +202,8 @@ bool AudioResource::UpdateProperty(const gd::String& name,
     preloadAsSound = value == "1";
   else if (name == _("Preload as music"))
     preloadAsMusic = value == "1";
+  else if (name == _("Preload as file"))
+    preloadAsFile = value == "1";
 
   return true;
 }

Core/GDCore/Project/ResourcesManager.h

@@ -223,7 +223,7 @@ class GD_CORE_API ImageResource : public Resource {
  */
 class GD_CORE_API AudioResource : public Resource {
  public:
-  AudioResource() : Resource(), preloadAsMusic(false), preloadAsSound(false) {
+  AudioResource() : Resource(), preloadAsMusic(false), preloadAsSound(false), preloadAsFile(false) {
     SetKind("audio");
   };
   virtual ~AudioResource(){};
@@ -263,10 +263,21 @@ class GD_CORE_API AudioResource : public Resource {
    */
   void SetPreloadAsSound(bool enable = true) { preloadAsSound = enable; }
 
+  /**
+   * \brief Return true if the audio resource should be preloaded as a file (without decoding).
+   */
+  bool PreloadAsFile() const { return preloadAsFile; }
+
+  /**
+   * \brief Set if the audio resource should be preloaded as a file (without decoding).
+   */
+  void SetPreloadAsFile(bool enable = true) { preloadAsFile = enable; }
+
  private:
   gd::String file;
   bool preloadAsSound;
   bool preloadAsMusic;
+  bool preloadAsFile;
 };
 
 /**

GDJS/Runtime/howler-sound-manager/howler-sound-manager.ts

@@ -802,24 +802,37 @@ namespace gdjs {
         if (!filesToLoad.length) return;
         const file = filesToLoad.shift()!;
         const fileData = files[file][0];
-        if (!fileData.preloadAsSound && !fileData.preloadAsMusic) {
-          onLoad();
-        } else if (fileData.preloadAsSound && fileData.preloadAsMusic) {
-          let loadedOnce = false;
-          const callback = (_, error) => {
-            if (!loadedOnce) {
-              loadedOnce = true;
-              return;
-            }
+
+        let loadCounter = 0;
+        const callback = (_?: any, error?: string) => {
+          loadCounter--;
+          if (!loadCounter) {
             onLoad(_, error);
-          };
+          }
+        };
 
+        if (fileData.preloadAsMusic) {
+          loadCounter++;
           preloadAudioFile(file, callback, /* isMusic= */ true);
+        }
+
+        if (fileData.preloadAsSound) {
+          loadCounter++;
           preloadAudioFile(file, callback, /* isMusic= */ false);
-        } else if (fileData.preloadAsSound) {
-          preloadAudioFile(file, onLoad, /* isMusic= */ false);
-        } else if (fileData.preloadAsMusic)
-          preloadAudioFile(file, onLoad, /* isMusic= */ true);
+        } else if (fileData.preloadAsFile) {
+          // preloading as sound already does a XHR request, hence "else if"
+          loadCounter++;
+          const sound = new XMLHttpRequest();
+          sound.addEventListener('load', callback);
+          sound.addEventListener('error', (_) => callback(_, "XHR error: " + file));
+          sound.addEventListener('abort', (_) => callback(_, "XHR abort: " + file));
+          sound.open('GET', file);
+          sound.send();
+        }
+
+        if (!loadCounter) {
+          onLoad();
+        }
       };
       loadNextFile();
     }

GDJS/Runtime/types/project-data.d.ts

@@ -220,6 +220,7 @@ declare interface ResourceData {
   disablePreload?: boolean;
   preloadAsSound?: boolean;
   preloadAsMusic?: boolean;
+  preloadAsFile?: boolean;
 }
 
 declare type ResourceKind =