Add Non-Uniform Border to Border. (flutter#121921)

bernaferrari · web-flow · commit 5054b6e514a7 · 2023-03-24T01:40:56.000Z
Add Non-Uniform Border to Border.
diff --git a/packages/flutter/lib/src/painting/box_border.dart b/packages/flutter/lib/src/painting/box_border.dart
@@ -212,7 +212,9 @@ abstract class BoxBorder extends ShapeBorder {
   ///
   /// See also:
   ///
-  ///  * [paintBorder], which is used if the border is not uniform.
+  ///  * [paintBorder], which is used if the border has non-uniform colors or styles and no borderRadius.
+  ///  * [Border.paint], similar to this method, includes additional comments
+  ///    and provides more details on each parameter than described here.
   @override
   void paint(
     Canvas canvas,
@@ -240,6 +242,62 @@ abstract class BoxBorder extends ShapeBorder {
     }
   }
 
+  static void _paintNonUniformBorder(
+    Canvas canvas,
+    Rect rect, {
+    required BorderRadius? borderRadius,
+    required BoxShape shape,
+    required TextDirection? textDirection,
+    required BorderSide left,
+    required BorderSide top,
+    required BorderSide right,
+    required BorderSide bottom,
+  }) {
+    final RRect borderRect;
+    switch(shape) {
+      case BoxShape.rectangle:
+        borderRect = (borderRadius ?? BorderRadius.zero)
+            .resolve(textDirection)
+            .toRRect(rect);
+      case BoxShape.circle:
+        assert(borderRadius == null, 'A borderRadius cannot be given when shape is a BoxShape.circle.');
+        borderRect = RRect.fromRectAndRadius(
+          Rect.fromCircle(center: rect.center, radius: rect.shortestSide / 2.0),
+          Radius.circular(rect.width),
+        );
+    }
+    final Paint paint = Paint()..color = top.color;
+    final RRect inner = _deflateRRect(borderRect, EdgeInsets.fromLTRB(left.strokeInset, top.strokeInset, right.strokeInset, bottom.strokeInset));
+    final RRect outer = _inflateRRect(borderRect, EdgeInsets.fromLTRB(left.strokeOutset, top.strokeOutset, right.strokeOutset, bottom.strokeOutset));
+    canvas.drawDRRect(outer, inner, paint);
+  }
+
+  static RRect _inflateRRect(RRect rect, EdgeInsets insets) {
+    return RRect.fromLTRBAndCorners(
+      rect.left - insets.left,
+      rect.top - insets.top,
+      rect.right + insets.right,
+      rect.bottom + insets.bottom,
+      topLeft: (rect.tlRadius + Radius.elliptical(insets.left, insets.top)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      topRight: (rect.trRadius + Radius.elliptical(insets.right, insets.top)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      bottomRight: (rect.brRadius + Radius.elliptical(insets.right, insets.bottom)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      bottomLeft: (rect.blRadius + Radius.elliptical(insets.left, insets.bottom)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+    );
+  }
+
+  static RRect _deflateRRect(RRect rect, EdgeInsets insets) {
+    return RRect.fromLTRBAndCorners(
+      rect.left + insets.left,
+      rect.top + insets.top,
+      rect.right - insets.right,
+      rect.bottom - insets.bottom,
+      topLeft: (rect.tlRadius - Radius.elliptical(insets.left, insets.top)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      topRight: (rect.trRadius - Radius.elliptical(insets.right, insets.top)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      bottomRight: (rect.brRadius - Radius.elliptical(insets.right, insets.bottom)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+      bottomLeft:(rect.blRadius - Radius.elliptical(insets.left, insets.bottom)).clamp(minimum: Radius.zero), // ignore_clamp_double_lint
+    );
+  }
+
   static void _paintUniformBorderWithCircle(Canvas canvas, Rect rect, BorderSide side) {
     assert(side.style != BorderStyle.none);
     final double radius = (rect.shortestSide + side.strokeOffset) / 2;
@@ -313,6 +371,10 @@ abstract class BoxBorder extends ShapeBorder {
 ///  * [BorderSide], which is used to describe each side of the box.
 ///  * [Theme], from the material layer, which can be queried to obtain appropriate colors
 ///    to use for borders in a [MaterialApp], as shown in the "divider" sample above.
+///  * [paint], which explains the behavior of [BoxDecoration] parameters.
+///  * <https://pub.dev/packages/non_uniform_border>, a package that implements
+///    a Non-Uniform Border on ShapeBorder, which is used by Material Design
+///    buttons and other widgets, under the "shape" field.
 class Border extends BoxBorder {
   /// Creates a border.
   ///
@@ -407,24 +469,24 @@ class Border extends BoxBorder {
 
   bool get _colorIsUniform {
     final Color topColor = top.color;
-    return right.color == topColor && bottom.color == topColor && left.color == topColor;
+    return left.color == topColor && bottom.color == topColor && right.color == topColor;
   }
 
   bool get _widthIsUniform {
     final double topWidth = top.width;
-    return right.width == topWidth && bottom.width == topWidth && left.width == topWidth;
+    return left.width == topWidth && bottom.width == topWidth && right.width == topWidth;
   }
 
   bool get _styleIsUniform {
     final BorderStyle topStyle = top.style;
-    return right.style == topStyle && bottom.style == topStyle && left.style == topStyle;
+    return left.style == topStyle && bottom.style == topStyle && right.style == topStyle;
   }
 
   bool get _strokeAlignIsUniform {
     final double topStrokeAlign = top.strokeAlign;
-    return right.strokeAlign == topStrokeAlign
+    return left.strokeAlign == topStrokeAlign
         && bottom.strokeAlign == topStrokeAlign
-        && left.strokeAlign == topStrokeAlign;
+        && right.strokeAlign == topStrokeAlign;
   }
 
   @override
@@ -491,14 +553,16 @@ class Border extends BoxBorder {
 
   /// Paints the border within the given [Rect] on the given [Canvas].
   ///
-  /// Uniform borders are more efficient to paint than more complex borders.
+  /// Uniform borders and non-uniform borders with similar colors and styles
+  /// are more efficient to paint than more complex borders.
   ///
   /// You can provide a [BoxShape] to draw the border on. If the `shape` in
-  /// [BoxShape.circle], there is the requirement that the border [isUniform].
+  /// [BoxShape.circle], there is the requirement that the border has uniform
+  /// color and style.
   ///
   /// If you specify a rectangular box shape ([BoxShape.rectangle]), then you
   /// may specify a [BorderRadius]. If a `borderRadius` is specified, there is
-  /// the requirement that the border [isUniform].
+  /// the requirement that the border has uniform color and style.
   ///
   /// The [getInnerPath] and [getOuterPath] methods do not know about the
   /// `shape` and `borderRadius` arguments.
@@ -507,7 +571,10 @@ class Border extends BoxBorder {
   ///
   /// See also:
   ///
-  ///  * [paintBorder], which is used if the border is not uniform.
+  ///  * [paintBorder], which is used if the border has non-uniform colors or styles and no borderRadius.
+  ///  * <https://pub.dev/packages/non_uniform_border>, a package that implements
+  ///    a Non-Uniform Border on ShapeBorder, which is used by Material Design
+  ///    buttons and other widgets, under the "shape" field.
   @override
   void paint(
     Canvas canvas,
@@ -523,7 +590,7 @@ class Border extends BoxBorder {
         case BorderStyle.solid:
           switch (shape) {
             case BoxShape.circle:
-              assert(borderRadius == null, 'A borderRadius can only be given for rectangular boxes.');
+              assert(borderRadius == null, 'A borderRadius cannot be given when shape is a BoxShape.circle.');
               BoxBorder._paintUniformBorderWithCircle(canvas, rect, top);
             case BoxShape.rectangle:
               if (borderRadius != null && borderRadius != BorderRadius.zero) {
@@ -536,36 +603,50 @@ class Border extends BoxBorder {
       }
     }
 
+    // Allow painting non-uniform borders if the color and style are uniform.
+    if (_colorIsUniform && _styleIsUniform) {
+      switch(top.style) {
+        case BorderStyle.none:
+          return;
+        case BorderStyle.solid:
+          BoxBorder._paintNonUniformBorder(canvas, rect,
+              shape: shape,
+              borderRadius: borderRadius,
+              textDirection: textDirection,
+              left: left,
+              top: top,
+              right: right,
+              bottom: bottom);
+          return;
+      }
+    }
+
     assert(() {
       if (borderRadius != null) {
         throw FlutterError.fromParts(<DiagnosticsNode>[
-          ErrorSummary('A borderRadius can only be given for a uniform Border.'),
+          ErrorSummary('A borderRadius can only be given on borders with uniform colors and styles.'),
           ErrorDescription('The following is not uniform:'),
           if (!_colorIsUniform) ErrorDescription('BorderSide.color'),
-          if (!_widthIsUniform) ErrorDescription('BorderSide.width'),
           if (!_styleIsUniform) ErrorDescription('BorderSide.style'),
-          if (!_strokeAlignIsUniform) ErrorDescription('BorderSide.strokeAlign'),
         ]);
       }
       return true;
     }());
     assert(() {
       if (shape != BoxShape.rectangle) {
         throw FlutterError.fromParts(<DiagnosticsNode>[
-          ErrorSummary('A Border can only be drawn as a circle if it is uniform.'),
+          ErrorSummary('A Border can only be drawn as a circle on borders with uniform colors and styles.'),
           ErrorDescription('The following is not uniform:'),
           if (!_colorIsUniform) ErrorDescription('BorderSide.color'),
-          if (!_widthIsUniform) ErrorDescription('BorderSide.width'),
           if (!_styleIsUniform) ErrorDescription('BorderSide.style'),
-          if (!_strokeAlignIsUniform) ErrorDescription('BorderSide.strokeAlign'),
         ]);
       }
       return true;
     }());
     assert(() {
       if (!_strokeAlignIsUniform || top.strokeAlign != BorderSide.strokeAlignInside) {
         throw FlutterError.fromParts(<DiagnosticsNode>[
-          ErrorSummary('A Border can only draw strokeAlign different than BorderSide.strokeAlignInside on uniform borders.'),
+          ErrorSummary('A Border can only draw strokeAlign different than BorderSide.strokeAlignInside on borders with uniform colors and styles.'),
         ]);
       }
       return true;
@@ -626,6 +707,9 @@ class Border extends BoxBorder {
 ///  * [BorderSide], which is used to describe each side of the box.
 ///  * [Theme], from the material layer, which can be queried to obtain appropriate colors
 ///    to use for borders in a [MaterialApp], as shown in the "divider" sample above.
+///  * <https://pub.dev/packages/non_uniform_border>, a package that implements
+///    a Non-Uniform Border on ShapeBorder, which is used by Material Design
+///    buttons and other widgets, under the "shape" field.
 class BorderDirectional extends BoxBorder {
   /// Creates a border.
   ///
@@ -698,33 +782,21 @@ class BorderDirectional extends BoxBorder {
   }
 
   @override
-  bool get isUniform {
+  bool get isUniform => _colorIsUniform && _widthIsUniform && _styleIsUniform && _strokeAlignIsUniform;
+
+  bool get _colorIsUniform {
     final Color topColor = top.color;
-    if (start.color != topColor ||
-        end.color != topColor ||
-        bottom.color != topColor) {
-      return false;
-    }
+    return start.color == topColor && bottom.color == topColor && end.color == topColor;
+  }
 
+  bool get _widthIsUniform {
     final double topWidth = top.width;
-    if (start.width != topWidth ||
-        end.width != topWidth ||
-        bottom.width != topWidth) {
-      return false;
-    }
+    return start.width == topWidth && bottom.width == topWidth && end.width == topWidth;
+  }
 
+  bool get _styleIsUniform {
     final BorderStyle topStyle = top.style;
-    if (start.style != topStyle ||
-        end.style != topStyle ||
-        bottom.style != topStyle) {
-      return false;
-    }
-
-    if (_strokeAlignIsUniform == false) {
-      return false;
-    }
-
-    return true;
+    return start.style == topStyle && bottom.style == topStyle && end.style == topStyle;
   }
 
   bool get _strokeAlignIsUniform {
@@ -850,7 +922,7 @@ class BorderDirectional extends BoxBorder {
   ///
   /// See also:
   ///
-  ///  * [paintBorder], which is used if the border is not uniform.
+  ///  * [paintBorder], which is used if the border has non-uniform colors or styles and no borderRadius.
   @override
   void paint(
     Canvas canvas,
@@ -866,7 +938,7 @@ class BorderDirectional extends BoxBorder {
         case BorderStyle.solid:
           switch (shape) {
             case BoxShape.circle:
-              assert(borderRadius == null, 'A borderRadius can only be given for rectangular boxes.');
+              assert(borderRadius == null, 'A borderRadius cannot be given when shape is a BoxShape.circle.');
               BoxBorder._paintUniformBorderWithCircle(canvas, rect, top);
             case BoxShape.rectangle:
               if (borderRadius != null && borderRadius != BorderRadius.zero) {
@@ -879,10 +951,6 @@ class BorderDirectional extends BoxBorder {
       }
     }
 
-    assert(borderRadius == null, 'A borderRadius can only be given for uniform borders.');
-    assert(shape == BoxShape.rectangle, 'A border can only be drawn as a circle if it is uniform.');
-    assert(_strokeAlignIsUniform && top.strokeAlign == BorderSide.strokeAlignInside, 'A Border can only draw strokeAlign different than strokeAlignInside on uniform borders.');
-
     final BorderSide left, right;
     assert(textDirection != null, 'Non-uniform BorderDirectional objects require a TextDirection when painting.');
     switch (textDirection!) {
@@ -893,6 +961,29 @@ class BorderDirectional extends BoxBorder {
         left = start;
         right = end;
     }
+
+    // Allow painting non-uniform borders if the color and style are uniform.
+    if (_colorIsUniform && _styleIsUniform) {
+      switch(top.style) {
+        case BorderStyle.none:
+          return;
+        case BorderStyle.solid:
+          BoxBorder._paintNonUniformBorder(canvas, rect,
+              shape: shape,
+              borderRadius: borderRadius,
+              textDirection: textDirection,
+              left: left,
+              top: top,
+              right: right,
+              bottom: bottom);
+          return;
+      }
+    }
+
+    assert(borderRadius == null, 'A borderRadius can only be given for borders with uniform colors and styles.');
+    assert(shape == BoxShape.rectangle, 'A Border can only be drawn as a circle on borders with uniform colors and styles.');
+    assert(_strokeAlignIsUniform && top.strokeAlign == BorderSide.strokeAlignInside, 'A Border can only draw strokeAlign different than strokeAlignInside on borders with uniform colors and styles.');
+
     paintBorder(canvas, rect, top: top, left: left, bottom: bottom, right: right);
   }
 
diff --git a/packages/flutter/test/material/data_table_test.dart b/packages/flutter/test/material/data_table_test.dart
@@ -1749,11 +1749,7 @@ void main() {
     );
     expect(
       find.ancestor(of: find.byType(Table), matching: find.byType(Container)),
-      paints
-        ..path(color: borderColor)
-        ..path(color: borderColor)
-        ..path(color: borderColor)
-        ..path(color: borderColor),
+      paints..drrect(color: borderColor),
     );
     expect(
       tester.getTopLeft(find.byType(Table)),
diff --git a/packages/flutter/test/painting/border_test.dart b/packages/flutter/test/painting/border_test.dart
