allow specifying target size when parsing svg

packages/vector_graphics/lib/src/listener.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:math';
 import 'dart:typed_data';
 import 'dart:ui';
 
@@ -62,6 +63,7 @@ Future<PictureInfo> decodeVectorGraphics(
   required bool clipViewbox,
   required BytesLoader loader,
   VectorGraphicsErrorListener? onError,
+  Size? targetSize,
 }) {
   try {
     // We might be in a test that's using a fake async zone. Make sure that any
@@ -86,6 +88,7 @@ Future<PictureInfo> decodeVectorGraphics(
         textDirection: textDirection,
         clipViewbox: clipViewbox,
         onError: onError,
+        targetSize: targetSize,
       );
       DecodeResponse response = _codec.decode(data, listener);
       if (response.complete) {
@@ -207,6 +210,7 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
     @visibleForTesting
     PictureFactory pictureFactory = const _DefaultPictureFactory(),
     VectorGraphicsErrorListener? onError,
+    Size? targetSize,
   }) {
     final PictureRecorder recorder = pictureFactory.createPictureRecorder();
     return FlutterVectorGraphicsListener._(
@@ -217,6 +221,7 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
       locale,
       textDirection,
       clipViewbox,
+      targetSize,
       onError: onError,
     );
   }
@@ -228,7 +233,8 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
     this._canvas,
     this._locale,
     this._textDirection,
-    this._clipViewbox, {
+    this._clipViewbox,
+    this._targetSize, {
     this.onError,
   });
 
@@ -239,6 +245,7 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
   final Locale? _locale;
   final TextDirection? _textDirection;
   final bool _clipViewbox;
+  final Size? _targetSize;
 
   final PictureRecorder _recorder;
   final Canvas _canvas;
@@ -474,6 +481,7 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
       _locale,
       _textDirection,
       _clipViewbox,
+      null,
     );
 
     patternListener._size =
@@ -558,6 +566,14 @@ class FlutterVectorGraphicsListener extends VectorGraphicsCodecListener {
 
   @override
   void onSize(double width, double height) {
+    final double targetWidth = _targetSize?.width ?? width;
+    final double targetHeight = _targetSize?.height ?? height;
+
+    final double sx = targetWidth / width;
+    final double sy = targetHeight / height;
+
+    _canvas.scale(min(sx, sy));
+
     if (_clipViewbox) {
       _canvas.clipRect(Offset.zero & Size(width, height));
     }

packages/vector_graphics/lib/src/vector_graphics.dart

@@ -7,12 +7,11 @@ import 'dart:ui' as ui;
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
-
 import 'package:vector_graphics_codec/vector_graphics_codec.dart';
 
 import 'html_render_vector_graphics.dart';
-import 'loader.dart';
 import 'listener.dart';
+import 'loader.dart';
 import 'render_object_selection.dart';
 import 'render_vector_graphic.dart';
 
@@ -680,6 +679,7 @@ class VectorGraphicUtilities {
     BuildContext? context, {
     bool clipViewbox = true,
     VectorGraphicsErrorListener? onError,
+    Size? targetSize,
   }) async {
     TextDirection textDirection = TextDirection.ltr;
     Locale locale = ui.PlatformDispatcher.instance.locale;
@@ -696,6 +696,7 @@ class VectorGraphicUtilities {
           loader: loader,
           clipViewbox: clipViewbox,
           onError: onError,
+          targetSize: targetSize,
         );
       } catch (e) {
         debugPrint('Failed to decode $loader');

packages/vector_graphics/test/scale/scale_test.dart

@@ -0,0 +1,88 @@
+import 'dart:ui' as ui;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:vector_graphics/src/listener.dart';
+import 'package:vector_graphics_compiler/vector_graphics_compiler.dart';
+
+import '../caching_test.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  late final ByteData vectorGraphicBuffer;
+  const String svgString = '''
+          <svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+          <path d="M18 21H7V8L14 1L15.25 2.25C15.3667 2.36667 15.4625 2.525 15.5375 2.725C15.6125 2.925 15.65 3.11667 15.65 3.3V3.65L14.55 8H21C21.5333 8 22 8.2 22.4 8.6C22.8 9 23 9.46667 23 10V12C23 12.1167 22.9833 12.2417 22.95 12.375C22.9167 12.5083 22.8833 12.6333 22.85 12.75L19.85 19.8C19.7 20.1333 19.45 20.4167 19.1 20.65C18.75 20.8833 18.3833 21 18 21ZM9 19H18L21 12V10H12L13.35 4.5L9 8.85V19ZM7 8V10H4V19H7V21H2V8H7Z" fill="#0066FF"/>
+          </svg>
+        ''';
+
+  setUpAll(() async {
+    final Uint8List bytes = encodeSvg(
+      xml: svgString,
+      debugName: 'test',
+      enableClippingOptimizer: false,
+      enableMaskingOptimizer: false,
+      enableOverdrawOptimizer: false,
+    );
+    vectorGraphicBuffer = bytes.buffer.asByteData();
+  });
+
+  setUp(() {
+    imageCache.clear();
+    imageCache.clearLiveImages();
+  });
+
+  Future<ui.Image> _decode({
+    required Size target,
+  }) async {
+    final PictureInfo info = await decodeVectorGraphics(
+      vectorGraphicBuffer,
+      locale: ui.PlatformDispatcher.instance.locale,
+      textDirection: ui.TextDirection.ltr,
+      clipViewbox: true,
+      loader: TestBytesLoader(vectorGraphicBuffer),
+      targetSize: target,
+    );
+    return info.picture.toImageSync(
+      target.width.toInt(),
+      target.height.toInt(),
+    );
+  }
+
+  testWidgets('resizes to the same size', (_) async {
+    final ui.Image image = await _decode(
+      target: const Size(24, 24),
+    );
+
+    await expectLater(
+      image,
+      matchesGoldenFile('thumb_up_24px.png'),
+    );
+  });
+
+  testWidgets('resizes to larger size', (_) async {
+    final ui.Image image = await _decode(
+      target: const Size(64, 64),
+    );
+
+    await expectLater(
+      image,
+      matchesGoldenFile('thumb_up_64px.png'),
+    );
+  });
+
+  testWidgets('resizes to smaller size', (_) async {
+    final ui.Image image = await _decode(
+      target: const Size(16, 16),
+    );
+
+    await expectLater(
+      image,
+      matchesGoldenFile('thumb_up_16px.png'),
+    );
+  });
+}