Changed the SvgIntegration to parse metadata, and include the image's…

… width/height in the generated assets.gen.dart.

packages/core/lib/generators/integrations/svg_integration.dart

@@ -1,11 +1,17 @@
+import 'dart:io';
+
 import 'package:flutter_gen_core/generators/integrations/integration.dart';
 import 'package:flutter_gen_core/settings/asset_type.dart';
+import 'package:vector_graphics_compiler/vector_graphics_compiler.dart';
 
 class SvgIntegration extends Integration {
-  SvgIntegration(String packageName) : super(packageName);
+  SvgIntegration(String packageName, {this.parseMetadata = false})
+      : super(packageName);
 
   String get packageExpression => isPackage ? ' = package' : '';
 
+  final bool parseMetadata;
+
   @override
   List<String> get requiredImports => [
         'package:flutter/widgets.dart',
@@ -17,11 +23,11 @@ class SvgIntegration extends Integration {
   String get classOutput => _classDefinition;
 
   String get _classDefinition => '''class SvgGenImage {
-  const SvgGenImage(this._assetName);
+  const SvgGenImage(this._assetName, {this.size = null});
 
   final String _assetName;
-
-  ${isPackage ? "static const String package = '$packageName';" : ''}
+  final Size? size;
+${isPackage ? "\n  static const String package = '$packageName';" : ''}
 
   SvgPicture svg({
     Key? key,
@@ -76,12 +82,43 @@ class SvgIntegration extends Integration {
   String get className => 'SvgGenImage';
 
   @override
-  String classInstantiate(AssetType asset) =>
-      'SvgGenImage(\'${asset.posixStylePath}\')';
+  String classInstantiate(AssetType asset) {
+    // Query extra information about the SVG
+    SvgInfo? info = parseMetadata ? _getMetadata(asset) : null;
+
+    return 'SvgGenImage(\'${asset.posixStylePath}\''
+        '${(info != null) ? ', size: Size(${info.width}, ${info.height})' : ''}'
+        ')';
+  }
+
+  SvgInfo? _getMetadata(AssetType asset) {
+    try {
+      // The SVG file is read fully, then parsed with the vector_graphics
+      // library. This is quite a heavy way to extract just the dimenions, but
+      // it's also the same way it will be eventually rendered by Flutter.
+      final svg = File(asset.fullPath).readAsStringSync();
+      final vec = parseWithoutOptimizers(svg);
+      return SvgInfo(vec.width, vec.height);
+    } catch (e) {
+      stderr.writeln(
+          '[WARNING] Failed to parse SVG \'${asset.path}\' metadata: $e');
+    }
+
+    return null;
+  }
 
   @override
   bool isSupport(AssetType asset) => asset.mime == 'image/svg+xml';
 
   @override
   bool get isConstConstructor => true;
 }
+
+/// Useful metadata about the a parsed SVG file.
+/// Currently only contains the width and height.
+class SvgInfo {
+  final double width;
+  final double height;
+
+  SvgInfo(this.width, this.height);
+}

packages/core/pubspec.yaml

@@ -26,6 +26,7 @@ dependencies:
   dart_style: ^2.2.4
   args: ^2.0.0
   pub_semver: ^2.0.0
+  vector_graphics_compiler: ^1.1.9
 
 dev_dependencies:
   lints: any # Ignoring the version to allow editing across SDK versions.

packages/core/test/assets_gen_test.dart

@@ -108,6 +108,14 @@ void main() {
 
       await expectedAssetsGen(pubspec, generated, fact);
     });
+
+    test('Assets with parse metadata enabled', () async {
+      const pubspec = 'test_resources/pubspec_assets_parse_metadata.yaml';
+      const fact = 'test_resources/actual_data/assets_parse_metadata.gen.dart';
+      const generated = 'test_resources/lib/gen/assets_parse_metadata.gen.dart';
+
+      await expectedAssetsGen(pubspec, generated, fact);
+    });
   });
 
   group('Test generatePackageNameForConfig', () {