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115 lines
3.5 KiB
Markdown
115 lines
3.5 KiB
Markdown
<!--
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* @Description:
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* @Author: ekibun
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* @Date: 2020-08-08 08:16:50
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* @LastEditors: ekibun
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* @LastEditTime: 2020-09-22 00:03:48
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-->
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# flutter_qjs
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A quickjs engine for flutter.
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## Feature
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This plugin is a simple js engine for flutter using the `quickjs` project with `dart:ffi`. Plugin currently supports all the platforms except web!
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Event loop of `FlutterQjs` should be implemented by calling `FlutterQjs.dispatch()`.
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ES6 module with `import` function is supported and can be managed in dart with `setModuleHandler`.
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A global function `convert` is presented to invoke dart function. Data conversion between dart and js are implemented as follow:
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| dart | js |
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| --- | --- |
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| Bool | boolean |
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| Int | number |
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| Double | number |
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| String | string |
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| Uint8List | ArrayBuffer |
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| List | Array |
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| Map | Object |
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| JSFunction | function(....args) |
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| Future | Promise |
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**notice:** `function` can only be sent from js to dart. `Promise` return by `evaluate` will be automatically tracked and return the resolved data.
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## Getting Started
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1. Create a `FlutterQjs` object. Call `dispatch` to dispatch event loop.
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```dart
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final engine = FlutterQjs();
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await engine.dispatch();
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```
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2. Call `setMethodHandler` to implement `dart` interaction. For example, you can use `Dio` to implement http in js:
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```dart
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await engine.setMethodHandler((String method, List arg) {
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switch (method) {
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case "http":
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return Dio().get(arg[0]).then((response) => response.data);
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default:
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throw Exception("No such method");
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}
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});
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```
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and in javascript, call `convert` function to get data, make sure the second memeber is a list:
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```javascript
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convert("http", ["http://example.com/"]);
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```
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3. Call `setModuleHandler` to resolve the js module.
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**important:** I cannot find a way to convert the sync ffi callback into an async function. So the assets files received by async function `rootBundle.loadString` cannot be used in this version. I will appreciate it if you can provide me a solution to make `ModuleHandler` async.
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```dart
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await engine.setModuleHandler((String module) {
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if(module == "hello") return "export default (name) => `hello \${name}!`;";
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throw Exception("Module Not found");
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});
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```
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and in javascript, call `import` function to get module:
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```javascript
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import("hello").then(({default: greet}) => greet("world"));
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```
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4. Use `evaluate` to run js script:
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```dart
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try {
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print(await engine.evaluate(code ?? '', "<eval>"));
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} catch (e) {
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print(e.toString());
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}
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```
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5. Method `recreate` can destroy quickjs runtime that can be recreated again if you call `evaluate`, `recreat` can be used to reset the module cache. Call `close` to stop `dispatch` when you do not need it.
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[This example](example/lib/main.dart) contains a complete demonstration on how to use this plugin.
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## For Mac & IOS developer
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I am new to Xcode and iOS developing, and I cannot find a better way to support both simulators and real devices without combining the binary frameworks. To reduce build size, change the `s.vendored_frameworks` in `ios/flutter_qjs.podspec` to the specific framework.
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For simulator, use:
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```podspec
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s.vendored_frameworks = `build/Debug-iphonesimulator/ffiquickjs.framework`
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```
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For real device, use:
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```podspec
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s.vendored_frameworks = `build/Debug-iphoneos/ffiquickjs.framework`
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```
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Two additional notes:
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1. quickjs built with `release` config has bug in resolving `Promise`. Please let me know if you know the solution.
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2. `ios/make.sh` limit the build architectures to avoid combine conflicts. Change the `make.sh` to support another architectures. |