Added LinearBorder, an OutlinedBorder like BoxBorder (#116940)

examples/api/test/painting/linear_border.0_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import 'package:flutter_api_samples/painting/linear_border/linear_border.0.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Smoke Test', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.ExampleApp(),
+    );
+    expect(find.byType(example.Home), findsOneWidget);
+
+    // Scroll the interpolation example into view
+
+    await tester.scrollUntilVisible(
+      find.byIcon(Icons.play_arrow),
+      500.0,
+      scrollable: find.byType(Scrollable),
+    );
+    expect(find.byIcon(Icons.play_arrow), findsOneWidget);
+
+    // Run the interpolation example
+
+    await tester.tap(find.byIcon(Icons.play_arrow));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byIcon(Icons.play_arrow));
+    await tester.pumpAndSettle();
+
+    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.text('Interpolation')));
+    await gesture.moveTo(tester.getCenter(find.text('Hover')));
+    await tester.pumpAndSettle();
+    await gesture.moveTo(tester.getCenter(find.text('Interpolation')));
+    await tester.pumpAndSettle();
+  });
+}

packages/flutter/lib/painting.dart

@@ -47,6 +47,7 @@ export 'src/painting/image_provider.dart';
 export 'src/painting/image_resolution.dart';
 export 'src/painting/image_stream.dart';
 export 'src/painting/inline_span.dart';
+export 'src/painting/linear_border.dart';
 export 'src/painting/matrix_utils.dart';
 export 'src/painting/notched_shapes.dart';
 export 'src/painting/oval_border.dart';

packages/flutter/test/painting/linear_border_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/painting.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../rendering/mock_canvas.dart';
+
+
+const Rect canvasRect = Rect.fromLTWH(0, 0, 100, 100);
+const BorderSide borderSide = BorderSide(width: 4, color: Color(0x0f00ff00));
+
+// Test points for rectangular filled paths based on a BorderSide with width 4 and
+// a 100x100 bounding rectangle (canvasRect).
+List<Offset> rectIncludes(Rect r) {
+  return <Offset>[r.topLeft, r.topRight, r.bottomLeft, r.bottomRight, r.center];
+}
+final List<Offset> leftRectIncludes = rectIncludes(const Rect.fromLTWH(0, 0, 4, 100));
+final List<Offset> rightRectIncludes = rectIncludes(const Rect.fromLTWH(96, 0, 4, 100));
+final List<Offset> topRectIncludes = rectIncludes(const Rect.fromLTWH(0, 0, 100, 4));
+final List<Offset> bottomRectIncludes = rectIncludes(const Rect.fromLTWH(0, 96, 100, 4));
+
+
+void main() {
+  test('LinearBorderEdge defaults', () {
+    expect(const LinearBorderEdge().size, 1);
+    expect(const LinearBorderEdge().alignment, 0);
+  });
+
+  test('LinearBorder defaults', () {
+    void expectEmptyBorder(LinearBorder border) {
+      expect(border.side, BorderSide.none);
+      expect(border.dimensions, EdgeInsets.zero);
+      expect(border.preferPaintInterior, false);
+      expect(border.start, null);
+      expect(border.end, null);
+      expect(border.top, null);
+      expect(border.bottom, null);
+    }
+    expectEmptyBorder(LinearBorder.none);
+
+    expect(LinearBorder.start().side, BorderSide.none);
+    expect(LinearBorder.start().start, const LinearBorderEdge());
+    expect(LinearBorder.start().end, null);
+    expect(LinearBorder.start().top, null);
+    expect(LinearBorder.start().bottom, null);
+
+    expect(LinearBorder.end().side, BorderSide.none);
+    expect(LinearBorder.end().start, null);
+    expect(LinearBorder.end().end, const LinearBorderEdge());
+    expect(LinearBorder.end().top, null);
+    expect(LinearBorder.end().bottom, null);
+
+    expect(LinearBorder.top().side, BorderSide.none);
+    expect(LinearBorder.top().start, null);
+    expect(LinearBorder.top().end, null);
+    expect(LinearBorder.top().top, const LinearBorderEdge());
+    expect(LinearBorder.top().bottom, null);
+
+    expect(LinearBorder.bottom().side, BorderSide.none);
+    expect(LinearBorder.bottom().start, null);
+    expect(LinearBorder.bottom().end, null);
+    expect(LinearBorder.bottom().top, null);
+    expect(LinearBorder.bottom().bottom, const LinearBorderEdge());
+  });
+
+  test('LinearBorder copyWith, ==, hashCode', () {
+    expect(LinearBorder.none, LinearBorder.none.copyWith());
+    expect(LinearBorder.none.hashCode, LinearBorder.none.copyWith().hashCode);
+    const BorderSide side = BorderSide(width: 10.0, color: Color(0xff123456));
+    expect(LinearBorder.none.copyWith(side: side), const LinearBorder(side: side));
+  });
+
+  test('LinearBorderEdge, LinearBorder toString()', () {
+    expect(const LinearBorderEdge(size: 0.5, alignment: -0.5).toString(), 'LinearBorderEdge(size: 0.5, alignment: -0.5)');
+    expect(LinearBorder.none.toString(), 'LinearBorder.none');
+    const BorderSide side = BorderSide(width: 10.0, color: Color(0xff123456));
+    expect(const LinearBorder(side: side).toString(), 'LinearBorder(side: BorderSide(color: Color(0xff123456), width: 10.0))');
+    expect(
+      const LinearBorder(
+        side: side,
+        start: LinearBorderEdge(size: 0, alignment: -0.75),
+        end: LinearBorderEdge(size: 0.25, alignment: -0.5),
+        top: LinearBorderEdge(size: 0.5, alignment: 0.5),
+        bottom: LinearBorderEdge(size: 0.75, alignment: 0.75),
+      ).toString(),
+      'LinearBorder('
+        'side: BorderSide(color: Color(0xff123456), width: 10.0), '
+        'start: LinearBorderEdge(size: 0.0, alignment: -0.75), '
+        'end: LinearBorderEdge(size: 0.25, alignment: -0.5), '
+        'top: LinearBorderEdge(size: 0.5, alignment: 0.5), '
+        'bottom: LinearBorderEdge(size: 0.75, alignment: 0.75))',
+    );
+  },
+    skip: isBrowser, // [intended] see https://github.com/flutter/flutter/issues/118207
+  );
+
+  test('LinearBorder.start()', () {
+    final LinearBorder border = LinearBorder.start(side: borderSide);
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.ltr),
+      paints
+        ..path(
+          includes: leftRectIncludes,
+          excludes: rightRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.rtl),
+      paints
+        ..path(
+          includes: rightRectIncludes,
+          excludes: leftRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+  });
+
+  test('LinearBorder.end()', () {
+    final LinearBorder border = LinearBorder.end(side: borderSide);
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.ltr),
+      paints
+        ..path(
+          includes: rightRectIncludes,
+          excludes: leftRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.rtl),
+      paints
+        ..path(
+          includes: leftRectIncludes,
+          excludes: rightRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+  });
+
+  test('LinearBorder.top()', () {
+    final LinearBorder border = LinearBorder.top(side: borderSide);
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.ltr),
+      paints
+        ..path(
+          includes: topRectIncludes,
+          excludes: bottomRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+  });
+
+  test('LinearBorder.bottom()', () {
+    final LinearBorder border = LinearBorder.bottom(side: borderSide);
+    expect(
+      (Canvas canvas) => border.paint(canvas, canvasRect, textDirection: TextDirection.ltr),
+      paints
+        ..path(
+          includes: bottomRectIncludes,
+          excludes: topRectIncludes,
+          color: borderSide.color,
+        ),
+    );
+  });
+}