Native Modules in Electron

Talk given at Bay Area Electron User Group

1. Na#ve Modules in Electron Paul Be(s (@paulcbe(s)
2. Why?
3. Na#ve modules let you do ! Anything !
4. Such as? • Showing Windows 10 No0fica0ons • Detec0ng the current keyboard layout and language • Doing language / script detec0on of text via cld2 • Spellchecking • Checking whether the OS is in presenta0on mode • Detec0ng whether we're in a Remote Desktop session
5. Crea%ng a Na%ve Node Module • Write some C++ code that integrates with node.js, just like you would for server-side node.js • Go?a think about three different plaCorms • Debugging is Not A Joy, but at least you can try your module in node.js first • Always, always, always use nodejs/nan
6. Crea%ng a Na%ve Node Module h"ps:/ /github.com/atom/node-spellchecker is the canonical Electron na:ve node.js module. It shows: • How to write OS-specific implementa5ons • Split your normal C++ code away from your Nan code and integrate it at the last minute • Write the bare minimum C++ code and use a JS shim to fill in the blanks (lib/spellchecker.js)
7. Not All Nodes Are Created Equal • Electron typically ships a super-ass new version of io.js, and your system node.js probably isn't that, so anything you install via npm install is Borked • Even if they're the same, on Windows, you'll get module iniAalizaAon failures if you try to use an io.js module
8. ❓❓ Wat do ❓❓
9. ! electron-rebuild !
10. electron-rebuild rebuilds na0ve node modules for you
11. electron-rebuild, easy mode `npm install nslog` `./node_modules/.bin/electron-rebuild`
12. electron-rebuild, not so easy mode shouldRebuildNativeModules(pathToElectron) .then((shouldBuild) => { if (!shouldBuild) return true; return installNodeHeaders('v0.30.5') .then(() => rebuildNativeModules('v0.30.5', './node_modules')); }) .catch((e) => { console.error("Building modules didn't work!"); console.error(e); });
13. node-ffi - a "generic" na.ve node module
14. node-ffi OSVERSIONINFO = OSVERSIONINFO || refStruct({ dwOSVersionInfoSize: ref.types.uint32, dwMajorVersion: ref.types.uint32, dwMinorVersion: ref.types.uint32, dwBuildNumber: ref.types.uint32, dwPlatformId: ref.types.uint32, szCSDVersion: refArray(ref.types.byte, 128), }); pLASTINPUTINFO = pLASTINPUTINFO || ref.refType(LASTINPUTINFO); pOSVERSIONINFO = pOSVERSIONINFO || ref.refType(OSVERSIONINFO); kernel32 = kernel32 || ffi.Library('kernel32', { 'GetVersionExA': [ 'int', [ pOSVERSIONINFO ] ], 'GetLastError': [ 'uint32', [] ] });
15. node-ffi getOSVersion: () => { let result = new OSVERSIONINFO(); result.dwOSVersionInfoSize = OSVERSIONINFO.size; let failed = (kernel32.GetVersionExA(result.ref()) === 0); if (failed) { let gle = kernel32.GetLastError(); throw new Error(`Failed to get version information: 0x${gle.toString(16)}`); } return { major: result.dwMajorVersion, minor: result.dwMinorVersion, build: result.dwBuildNumber, }; }
16. edge.js - call C# code from JavaScript import edge from 'edge-atom-shell'
17. edge.js import edge from 'edge-atom-shell' const helloWorld = edge.func(function () {/* async (input) => { return "This is C# code: " + input.ToString(); } */}); helloWorld('JavaScript', (error, result) => { if (error) throw error; console.log(result); });
18. edge.js public async Task<object> Invoke(object isWin10) { try { var notifier = (bool)isWin10 ? (INotifier)new Win10Notifier() : (INotifier)new Win7Notifier(); var ret = new Func<object, Task<object>>(async opts => { if (opts == null) { notifier.Dispose(); return null; } return await notifier.ShowNotification((string)opts); }); return ret; } catch (Exception ex) { return ex.ToString(); } }
19. Thanks! h"ps:/ /github.com/atom/node-spellchecker h"ps:/ /github.com/electronjs/electron-rebuild h"ps:/ /github.com/node-ffi/node-ffi h"ps:/ /github.com/paulcbe"s/edge