✨ Support build.yaml to configure

README.md

@@ -169,6 +169,24 @@ flutter:
           style: italic
 ```
 
+### build.yaml
+
+You can also configure generate options in the `build.yaml`, it will be read before the `pubspec.yaml` if it exists.
+
+
+```yaml
+# build.yaml
+# ...
+
+targets:
+  $default:
+    builders:
+      flutter_gen:
+        options: 
+          output: lib/build_gen/ # Optional (default: lib/gen/)
+          line_length: 120 # Optional (default: 80)
+```
+
 ## Available Parsers
 
 ### Assets
@@ -296,6 +314,28 @@ class $AssetsImagesGen {
 }
 ```
 
+#### Support generate at **build.yaml**
+Support generates dart files based on the key **`targets.$default.builders`** and **`flutter_gen.options`** 
+of [`build.yaml`](https://github.com/dart-lang/build/blob/master/build_config/README.md).
+
+```yaml
+# build.yaml
+# ...
+
+targets:
+  $default:
+    builders:
+      flutter_gen:
+        options: 
+          output: lib/build_gen/ # Optional (default: lib/gen/)
+          line_length: 120 # Optional (default: 80)
+```
+##### Prority of configure (High -> Low)
+```
+build.yaml -> pubspec.yaml -> default_config
+```
+
+
 #### Including additional metadata
 
 At build time, additional metadata may be included in the generated class, by using the

packages/command/bin/flutter_gen_command.dart

@@ -14,6 +14,13 @@ void main(List<String> args) {
     defaultsTo: 'pubspec.yaml',
   );
 
+  parser.addOption(
+    'build',
+    abbr: 'b',
+    help: 'Set the path of build.yaml.',
+    defaultsTo: 'build.yaml',
+  );
+
   parser.addFlag(
     'help',
     abbr: 'h',
@@ -45,5 +52,10 @@ void main(List<String> args) {
   }
 
   final pubspecPath = safeCast<String>(results['config']);
-  FlutterGenerator(File(pubspecPath!).absolute).build();
+  final pubspecFile = File(pubspecPath!).absolute;
+
+  final buildPath = safeCast<String>(results['build']);
+  final buildFile = File(buildPath!).absolute;
+
+  FlutterGenerator(pubspecFile, buildFile: buildFile).build();
 }

packages/core/lib/flutter_generator.dart

@@ -11,18 +11,20 @@ import 'package:path/path.dart';
 class FlutterGenerator {
   const FlutterGenerator(
     this.pubspecFile, {
+    this.buildFile,
     this.assetsName = 'assets.gen.dart',
     this.colorsName = 'colors.gen.dart',
     this.fontsName = 'fonts.gen.dart',
   });
 
   final File pubspecFile;
+  final File? buildFile;
   final String assetsName;
   final String colorsName;
   final String fontsName;
 
   Future<void> build({Config? config, FileWriter? writer}) async {
-    config ??= loadPubspecConfigOrNull(pubspecFile);
+    config ??= loadPubspecConfigOrNull(pubspecFile, buildFile: buildFile);
     if (config == null) return;
 
     final flutter = config.pubspec.flutter;

packages/core/lib/settings/config.dart

@@ -15,23 +15,49 @@ class Config {
   final File pubspecFile;
 }
 
-Config loadPubspecConfig(File pubspecFile) {
-  stdout.writeln('$flutterGenVersion Loading ... '
-      '${normalize(join(
-    basename(pubspecFile.parent.path),
-    basename(pubspecFile.path),
-  ))}');
-  final content = pubspecFile.readAsStringSync();
-  final userMap = loadYaml(content) as Map?;
+Config loadPubspecConfig(File pubspecFile, {File? buildFile}) {
+  final pubspecLocaleHint = normalize(
+    join(basename(pubspecFile.parent.path), basename(pubspecFile.path)),
+  );
+  final buildLocaleHint = buildFile != null && buildFile.existsSync()
+      ? join(basename(buildFile.parent.path), basename(buildFile.path))
+      : '';
+
+  stdout.writeln(
+    '$flutterGenVersion Loading ...',
+  );
+
   final defaultMap = loadYaml(configDefaultYamlContent) as Map?;
-  final mergedMap = mergeMap([defaultMap, userMap]);
+
+  final pubspecContent = pubspecFile.readAsStringSync();
+  final pubspecMap = loadYaml(pubspecContent) as Map?;
+
+  var mergedMap = mergeMap([defaultMap, pubspecMap]);
+  stdout.writeln(
+    'Reading FlutterGen options from $pubspecLocaleHint',
+  );
+
+  if (buildFile != null && buildFile.existsSync()) {
+    final buildContent = buildFile.readAsStringSync();
+    final rawMap = loadYaml(buildContent) as Map?;
+    final optionBuildMap = rawMap?['targets']?[r'$default']?['builders']?['flutter_gen']?['options'];
+
+    if (optionBuildMap != null) {
+      final buildMap = {'flutter_gen': optionBuildMap};
+      mergedMap = mergeMap([mergedMap, buildMap]);
+      stdout.writeln(
+        'Reading FlutterGen options from $buildLocaleHint',
+      );
+    }
+  }
+
   final pubspec = Pubspec.fromJson(mergedMap);
   return Config._(pubspec: pubspec, pubspecFile: pubspecFile);
 }
 
-Config? loadPubspecConfigOrNull(File pubspecFile) {
+Config? loadPubspecConfigOrNull(File pubspecFile, {File? buildFile}) {
   try {
-    return loadPubspecConfig(pubspecFile);
+    return loadPubspecConfig(pubspecFile, buildFile: buildFile);
   } on FileSystemException catch (e) {
     stderr.writeln(e.message);
   } on InvalidSettingsException catch (e) {

packages/core/test/flutter_gen_test.dart

@@ -179,5 +179,27 @@ void main() {
       expect(File('test_resources/lib/gen/$fonts').existsSync(), false);
       expect(File('test_resources/lib/gen/$colors').existsSync(), false);
     });
+
+    test('with build_output.yaml', () async {
+      const pubspec = 'test_resources/pubspec_normal.yaml';
+      const build = 'test_resources/build_output.yaml';
+      const assets = 'pubspec_assets.gen.dart';
+      const colors = 'pubspec_colors.gen.dart';
+      const fonts = 'pubspec_fonts.gen.dart';
+
+      await FlutterGenerator(
+        File(pubspec),
+        buildFile: File(build),
+        assetsName: assets,
+        colorsName: colors,
+        fontsName: fonts,
+      ).build();
+      expect(File('test_resources/lib/build_gen/$assets').readAsStringSync(),
+          isNotEmpty);
+      expect(File('test_resources/lib/build_gen/$fonts').readAsStringSync(),
+          isNotEmpty);
+      expect(File('test_resources/lib/build_gen/$colors').readAsStringSync(),
+          isNotEmpty);
+    });
   });
 }

packages/core/test_resources/build_output.yaml

@@ -0,0 +1,19 @@
+name: test
+
+targets:
+  $default:
+    builders:
+      flutter_gen:
+        options:
+          output: lib/build_gen/
+          line_length: 80
+
+          integrations:
+            flutter_svg: true
+            flare_flutter: true
+            rive: true
+            lottie: true
+
+          colors:
+            inputs:
+              - assets/color/colors.xml

packages/runner/lib/flutter_gen_runner.dart

@@ -21,8 +21,15 @@ class FlutterGenBuilder extends Builder {
     );
   }
 
-  final generator = FlutterGenerator(File('pubspec.yaml'));
-  late final _config = loadPubspecConfigOrNull(generator.pubspecFile);
+  final generator = FlutterGenerator(
+    File('pubspec.yaml'),
+    buildFile: File('build.yaml'),
+  );
+
+  late final _config = loadPubspecConfigOrNull(
+    generator.pubspecFile,
+    buildFile: generator.buildFile,
+  );
   _FlutterGenBuilderState? _currentState;
 
   @override