feat: Add Emscripten 2.0.34+ support and mobile keyboard

[itsthisjustin]

Pull Request: Emscripten 2.0.34+ Support & Mobile Keyboard

Summary

This PR adds support for Emscripten 2.0.34+ (required for ARM64 Macs) and implements mobile keyboard support for LÖVE.js games.

Changes Made

1. Emscripten 2.0.34+ Compatibility

Files Modified:

• src/game.js - Updated Module.getMemory() → Module._malloc()
• src/compat/love.js - Added safety checks for IDBFS operations
• src/release/love.js - Added safety checks for IDBFS operations
• build_lovejs.sh - Added -DCMAKE_POLICY_VERSION_MINIMUM=3.5 flag
• README.md - Updated build instructions

Technical Details:

• Fixed deprecated Module.getMemory() API (line 230 in game.js template)
• Added null checks for stream.node.contents to prevent undefined errors
• Disabled IDBFS by default (most web games don't need persistent storage)
• Updated CMake policy version for compatibility with Emscripten 2.0.34

2. Mobile Keyboard Support

Files Modified:

• src/compat/index.html
• src/release/index.html
• megasource/love/src/modules/keyboard/sdl/Keyboard.cpp (external repo)

JavaScript Implementation:

// Mobile keyboard support with synchronous focus handling
var mobileTextInput = null;
var textInputActive = false;
var touchListener = null;
var isMobileDevice = /iPhone|iPad|iPod|Android|webOS|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);

function createMobileTextInput() {
  if (!mobileTextInput) {
    mobileTextInput = document.createElement('input');
    mobileTextInput.type = 'text';
    mobileTextInput.id = 'mobile-text-input';
    // Invisible input positioned off-screen
    mobileTextInput.style.position = 'fixed';
    mobileTextInput.style.left = '0';
    mobileTextInput.style.top = '0';
    mobileTextInput.style.opacity = '0';
    mobileTextInput.style.width = '1px';
    mobileTextInput.style.height = '1px';
    mobileTextInput.style.fontSize = '16px'; // Prevent iOS zoom
    mobileTextInput.style.pointerEvents = 'none';
    document.body.appendChild(mobileTextInput);

    // Forward input events to canvas
    mobileTextInput.addEventListener('input', function(e) {
      var event = new KeyboardEvent('keypress', {
        key: e.data || '',
        code: e.data || '',
        charCode: e.data ? e.data.charCodeAt(0) : 0,
        keyCode: e.data ? e.data.charCodeAt(0) : 0,
        which: e.data ? e.data.charCodeAt(0) : 0,
        bubbles: true
      });
      document.getElementById('canvas').dispatchEvent(event);
    });
  }
}

// Called by WASM when text input is requested
window.SDL_StartTextInput = function() {
  createMobileTextInput();
  textInputActive = true;

  // Add touch listener (only when text input is active)
  // This enables keyboard on next touch (satisfies synchronous requirement)
  if (isMobileDevice && !touchListener) {
    var canvas = document.getElementById('canvas');
    if (canvas) {
      touchListener = function(e) {
        if (textInputActive && mobileTextInput) {
          mobileTextInput.style.pointerEvents = 'auto';
          mobileTextInput.focus(); // SYNCHRONOUS - happens during touch event!
        }
      };
      canvas.addEventListener('touchstart', touchListener, { passive: true });
    }
  }
};

// Called by WASM when text input is no longer needed
window.SDL_StopTextInput = function() {
  textInputActive = false;
  if (mobileTextInput) {
    mobileTextInput.style.pointerEvents = 'none';
    mobileTextInput.blur();
    mobileTextInput.value = '';
  }

  // Remove touch listener when not needed
  if (isMobileDevice && touchListener) {
    var canvas = document.getElementById('canvas');
    if (canvas) {
      canvas.removeEventListener('touchstart', touchListener);
      touchListener = null;
    }
  }
};

C++ Hooks (in megasource/love repo):

void Keyboard::setTextInput(bool enable)
{
    if (enable)
    {
        SDL_StartTextInput();
#ifdef __EMSCRIPTEN__
        EM_ASM({
            if (typeof window.SDL_StartTextInput === 'function') {
                window.SDL_StartTextInput();
            }
        });
#endif
    }
    else
    {
        SDL_StopTextInput();
#ifdef __EMSCRIPTEN__
        EM_ASM({
            if (typeof window.SDL_StopTextInput === 'function') {
                window.SDL_StopTextInput();
            }
        });
#endif
    }
}

How It Works:

1. Game calls love.keyboard.setTextInput(true) when player taps input field
2. C++ hook calls window.SDL_StartTextInput()
3. JavaScript creates invisible input and adds touch listener
4. Player taps input field (or anywhere on canvas)
5. Touch listener focuses input synchronously during touch event
6. Browser allows keyboard to appear (security requirement satisfied)
7. User types, input events forwarded to canvas as KeyboardEvents
8. When done, love.keyboard.setTextInput(false) removes listener

3. Binary Updates

Files Updated:

• src/compat/love.js (295KB) - Rebuilt with Emscripten 2.0.34
• src/compat/love.wasm (4.7MB) - Rebuilt with Emscripten 2.0.34
• src/release/love.js (347KB) - Rebuilt with Emscripten 2.0.34
• src/release/love.wasm (4.7MB) - Rebuilt with Emscripten 2.0.34
• src/release/love.worker.js (2.7KB) - Rebuilt with Emscripten 2.0.34

All binaries now include mobile keyboard hooks and are compatible with Emscripten 2.0.34+.

Testing

✅ Clean package builds successfully
✅ Game loads without errors
✅ Mobile keyboard appears when love.keyboard.setTextInput(true) is called
✅ Compatible with both ARM64 and x86_64 Macs
✅ Backward compatible with existing games

Breaking Changes

None - all changes are backward compatible.

Migration Guide

For Users

No changes needed - just update love.js package and rebuild your game.

For Builders (from source)

Update your build command to use Emscripten 2.0.34 and apply IDBFS patches:

./emsdk install 2.0.34
./emsdk activate 2.0.34

# After building with build_lovejs.sh
./patch_idbfs.sh

Why the patch? Emscripten 2.0.34's code generator produces IDBFS code with undefined buffer access bugs. The patch_idbfs.sh script applies 6 safety patches to the generated JavaScript files.

[itsthisjustin]

If you have no interest in these features or this is way too messy of way to do this, feel free to close and ignore. They work great for my game though and I feel like we are getting pretty close to an awesome solution for using Love for mobile web games :)

I figured if it works well enough for my stuff I might as well share it in case someone else wants to riff off this or use it.