A downloadable extension

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Quick links: source code
Versions: GameMaker: Studio, GameMaker Studio 2
Platforms: Windows, Windows (YYC) (see this extension for HTML5)

This extension allows the user to drag-and-drop files and directories onto the game window!

Featuring a total of 1 (one) function:

file_dropper_init()➜ Sets up the drag and drop operations for the game window. Should be called before you expect user to attempt dragging and dropping objects onto the window (usually on Game Start). Harmless if called more than once. Returns whether successful (I'm not aware of circumstances that could cause this function to fail).

After calling the said function, the game window will indicate to the system that it's happy to accept objects and the user will be able to drag and drop files from Explorer/etc. Doing so will dispatch one Async - System event per file, where

  • async_load[?"event_type"] is "file_drop"
  • async_load[?"filename"] is an absolute path to the file
    Note that in GMS1.4, you'll need an extension to read files outside of game/save directory (e.g. non-sandboxed filesystem)

Made available for free thanks to Follow The Fun (see more)


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Click download now to get access to the following files:

file_dropper-for-GMS1.gmez 57 kB
Version 1.0.0
file_dropper-for-GMS2.yymp 67 kB
Version 1.0.0
file_dropper-for-GMS2.3+.yymps 129 kB
Version 1.0.0


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I always get this error when trying to build, even on a blank project:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.ArgumentNullException: Value cannot be null. (Parameter 'path1')    at System.IO.Path.Combine(String path1, String path2)    at GMAssetCompiler.WADSaver`1.WriteExtensions(IList`1 _data, Stream _s, IFF _iff)    at GMAssetCompiler.IFFChunkHandler`1.Save(Stream _stream, IFF _iff)    at GMAssetCompiler.IFF.WriteChunks(Stream _stream, TextWriter _out)    at GMAssetCompiler.WADSaver`1.Save(GMAssets _assets, Stream _stream, List`1 _extraFilenames, Dictionary`2 _extraAttributes)    at GMAssetCompiler.IFFSaver.Save(GMAssets _assets, String _name)    at GMAssetCompiler.Program.CompileProject(GMAssets _file)    at GMAssetCompiler.Program.Reentry(String[] _args)    --- End of inner exception stack trace ---    at System.RuntimeMethodHandle.InvokeMethod(Object target, Span`1& arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)    at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)    at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)    at Igor.Program.ExecuteAssetCompiler(String _args)    at Igor.WindowsBuilder.Compile(Boolean _exe)    at Igor.WindowsBuilder.Deploy(Boolean _exe)    at Igor.WindowsBuilder.Run()

That’s a GameMaker bug - it corrupts most of my extensions on load now. I recommend rolling back the IDE to 2023.8 for now

(2 edits)

just as a head-up : The extension started not working for me all of a sudden, the function file_dropper_init() returning 0. I have no idea why, it worked fine until now, but now I can’t seem to get it to work on my computer anymore, except very rarely. I didn’t change any of the code, even old itch builds of my game that used to work do not now, so this is probably a change on my computer rather that on gamemaker, but I can’t figure out what change caused that to happen. Sometimes it will in fact work randomly but that’s like once every 20 tries. This is probably not helpful at all to debug but this is all I have :/

EDIT : I fixed it by disabling the option : Start fullscreen and running windo_set_fullscreen(true) at startup instead.

(5 edits) (+1)

Helper script:

To use this extension, simply call this once at launch: 
Then, put the following code in an async -> System event
Object -> Click "Add event"
"Asynchronous" (bottom right)
"System event" (last on the list).
// Check to see what kind of event happened
var eventType = ds_map_find_value(async_load,"event_type");
// If a file was dropped over the window
if eventType == "file_drop"
    // This is the absolute path
    var filePath = ds_map_find_value(async_load,"filename");
    // Print it 
    // Will return the full path, e.g. "C:\Users\user\Documents\Test.txt"
    // When multiple files are included, this event will be called
    // once per file. 

Nice! Very easy to use.