Clip image of BoxDecoration to circle when shape is BoxShape.circle (#63352)

packages/flutter/lib/src/painting/box_decoration.dart

@@ -219,7 +219,10 @@ class BoxDecoration extends Decoration {
     Path? clipPath;
     switch (shape) {
       case BoxShape.circle:
-        clipPath = Path()..addOval(rect);
+        final Offset center = rect.center;
+        final double radius = rect.shortestSide / 2.0;
+        final Rect square = Rect.fromCircle(center: center, radius: radius);
+        clipPath = Path()..addOval(square);
         break;
       case BoxShape.rectangle:
         if (borderRadius != null)
@@ -452,7 +455,11 @@ class _BoxDecorationPainter extends BoxPainter {
     Path? clipPath;
     switch (_decoration.shape) {
       case BoxShape.circle:
-        clipPath = Path()..addOval(rect);
+        assert(_decoration.borderRadius == null);
+        final Offset center = rect.center;
+        final double radius = rect.shortestSide / 2.0;
+        final Rect square = Rect.fromCircle(center: center, radius: radius);
+        clipPath = Path()..addOval(square);
         break;
       case BoxShape.rectangle:
         if (_decoration.borderRadius != null)

packages/flutter/test/painting/box_decoration_test.dart

@@ -71,7 +71,7 @@ void main() {
     );
   });
 
-  test('BoxDecoration.getClipPath', () {
+  test('BoxDecoration.getClipPath with borderRadius', () {
     const double radius = 10;
     final BoxDecoration decoration = BoxDecoration(
       borderRadius: BorderRadius.circular(radius),
@@ -84,4 +84,17 @@ void main() {
     );
     expect(clipPath, isLookLikeExpectedPath);
   });
+
+  test('BoxDecoration.getClipPath with shape BoxShape.circle', () {
+    const BoxDecoration decoration = BoxDecoration(
+      shape: BoxShape.circle,
+    );
+    const Rect rect = Rect.fromLTWH(0.0, 0.0, 100.0, 20.0);
+    final Path clipPath = decoration.getClipPath(rect, TextDirection.ltr);
+    final Matcher isLookLikeExpectedPath = isPathThat(
+      includes: const <Offset>[ Offset(50.0, 0.0), Offset(40.0, 10.0), ],
+      excludes: const <Offset>[ Offset(40.0, 0.0), Offset(10.0, 10.0), ],
+    );
+    expect(clipPath, isLookLikeExpectedPath);
+  });
 }