GMTextEdit

Note: this repo is AI generated so use with caution!

GMTextEdit is a small GameMaker + Odin project that wraps Odin's core:text/edit text editing primitives in a native extension for GameMaker.

The goal is to let GameMaker code create lightweight text editor states, send text input or editing commands to Odin, then read back the edited string, caret, selection, status, and clipboard state.

Windows uses a native DLL. Linux uses a native shared object. HTML5/GX uses a generated JavaScript extension that embeds the same Odin code compiled to WebAssembly, so the GML API stays the same across targets.

Project Layout

GMTextEdit/
  GM/                         GameMaker project
    extensions/ext_gmtextedit GameMaker extension resource and packaged DLL/SO
                              plus generated GX/HTML5 JavaScript bridge
    objects/                  Example object that demonstrates editing text
    rooms/Room1               Example room with the sample object
    scripts/                  Command/status enums for GameMaker
  Odin/
    textedit.odin             Odin source for the DLL and test runner
    textedit_wasm.odin        JS/Wasm scratch-buffer bridge helpers
    textedit_native_test.odin Native-only smoke tests and executable entry point
    build.bat                 Windows build script
    build_linux.sh            Linux build script
    build_gx.bat              GX/HTML5 Wasm + JavaScript bridge build script
    build_gx_bridge.ps1       Embeds the Wasm module into gmtextedit.js
    build/                    Build outputs

Requirements

GameMaker 2024 project format
Odin compiler
Windows/MSVC toolchain for the native DLL build in build.bat
Linux x86_64 host/toolchain for the native SO build in build_linux.sh
PowerShell for generating the GX/HTML5 JavaScript bridge

The GameMaker extension includes the Windows DLL:

GM/extensions/ext_gmtextedit/gmtextedit.dll

the Linux shared object:

GM/extensions/ext_gmtextedit/gmtextedit.so

and a generated JavaScript bridge for HTML5/GX:

GM/extensions/ext_gmtextedit/gmtextedit.js

macOS builds would need a matching shared library (.dylib) and GameMaker extension metadata for that target.

Building

Build and test the native Windows DLL, then regenerate the GX/HTML5 bridge:

Odin\build.bat

If you only need the GX/HTML5 JavaScript bridge, run:

Odin\build_gx.bat

build_gx.bat compiles Odin/build/gmtextedit.wasm with Odin's js_wasm32 target, then embeds that Wasm payload into GM/extensions/ext_gmtextedit/gmtextedit.js.

On Linux, build and test the native extension with:

Odin/build_linux.sh

Pass build to skip running the native smoke tests:

Odin/build_linux.sh build

GameMaker Example

Open the GameMaker project at:

GM/GMTextEdit.yyp

Room1 contains obj_gmtextedit_example, which:

creates an editor state with gmte_create
accepts typed input with gmte_input_text
handles common edit/navigation commands with gmte_command
draws the edited string
displays caret, anchor, selection, clipboard, and error status values
mirrors copied/cut text to the system clipboard and reads system clipboard text before paste

The example includes multiline text so Up/Down caret movement can be tested immediately.

GameMaker API

The extension functions are documented in:

GM/extensions/ext_gmtextedit/ext_gmtextedit.yy

Main functions:

Function	Purpose
`gmte_create(id, initial_text)`	Creates or resets an editor state.
`gmte_destroy(id)`	Destroys one editor state.
`gmte_destroy_all()`	Destroys every editor state.
`gmte_exists(id)`	Returns whether an editor exists.
`gmte_set_text(id, text)`	Replaces the editor text.
`gmte_get_text(id)`	Returns the current editor text.
`gmte_input_text(id, text)`	Inserts text at the caret or selection.
`gmte_command(id, command)`	Runs an edit/navigation command.
`gmte_set_selection(id, head, tail)`	Sets caret/selection byte indices.
`gmte_get_caret(id)`	Returns the caret byte index.
`gmte_get_anchor(id)`	Returns the selection anchor byte index.
`gmte_get_selection_start(id)`	Returns the lower selection byte index.
`gmte_get_selection_end(id)`	Returns the upper selection byte index.
`gmte_get_text_length(id)`	Returns text length in bytes.
`gmte_get_selected_text(id)`	Returns selected text.
`gmte_set_translate_by_grapheme(id, enabled)`	Toggles grapheme-aware left/right movement.
`gmte_clipboard_set(text)`	Sets the extension clipboard buffer.
`gmte_clipboard_get()`	Gets the extension clipboard buffer.
`gmte_last_status()`	Returns the last status code.
`gmte_last_error()`	Returns the last error message.

Commands

GameMaker command constants live in:

GM/scripts/scr_gmtextedit_constants/scr_gmtextedit_constants.gml

They mirror Odin's core:text/edit.Command values:

gmte_command(editor_id, GMTE_Command.Left);
gmte_command(editor_id, GMTE_Command.Right);
gmte_command(editor_id, GMTE_Command.Up);
gmte_command(editor_id, GMTE_Command.Down);
gmte_command(editor_id, GMTE_Command.SelectAll);
gmte_command(editor_id, GMTE_Command.Paste);

The numeric enum values are explicit because they are ABI constants shared with the Odin DLL.

Notes

Selection and caret positions are byte indices, not GameMaker character indices.
The extension stores text editor states by string id.
The extension clipboard functions use an internal buffer. The included GameMaker example mirrors Copy/Cut to the system clipboard when possible, but keeps a local fallback clipboard for GX/browser builds where clipboard_get_text() can return an empty string.
Up/Down and line-start/end movement are handled inside the Odin wrapper before dispatching to Odin's built-in text edit commands.