Implement computeDryBaseline for cupertino RenderBoxes (flutter#1…

…45951)

The `_debugVerifyDryBaselines` method verifies that dry baseline implementation is consistent with the wet baseline method at the current constraints.

packages/flutter/lib/src/cupertino/nav_bar.dart

@@ -939,11 +939,45 @@ class _RenderLargeTitle extends RenderShiftedBox {
 
   double _scale = 1.0;
 
+  static double _computeTitleScale(Size childSize, BoxConstraints constraints) {
+    const double maxHeight = _kNavBarLargeTitleHeightExtension - _kNavBarBottomPadding;
+    final double scale = 1.0 + 0.03 * (constraints.maxHeight - maxHeight) / maxHeight;
+    final double maxScale = childSize.width != 0.0
+      ? clampDouble(constraints.maxWidth / childSize.width, 1.0, 1.1)
+      : 1.1;
+    return clampDouble(scale, 1.0, maxScale);
+  }
+
   @override
-  void performLayout() {
+  double? computeDistanceToActualBaseline(TextBaseline baseline) {
+    final double? distance = child?.getDistanceToActualBaseline(baseline);
+    if (distance == null) {
+      return null;
+    }
+    final BoxParentData childParentData = child!.parentData! as BoxParentData;
+    return childParentData.offset.dy + distance * _scale;
+  }
+
+  @override
+  double? computeDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) {
     final RenderBox? child = this.child;
-    Size childSize = Size.zero;
+    if (child == null) {
+      return null;
+    }
+    final BoxConstraints childConstraints = constraints.widthConstraints().loosen();
+    final double? result = child.getDryBaseline(childConstraints, baseline);
+    if (result == null) {
+      return null;
+    }
+    final Size childSize = child.getDryLayout(childConstraints);
+    final double scale = _computeTitleScale(childSize, constraints);
+    final Size scaledChildSize = childSize * scale;
+    return result * scale + alignment.alongOffset(constraints.biggest - scaledChildSize as Offset).dy;
+  }
 
+  @override
+  void performLayout() {
+    final RenderBox? child = this.child;
     size = constraints.biggest;
 
     if (child == null) {
@@ -952,19 +986,9 @@ class _RenderLargeTitle extends RenderShiftedBox {
 
     final BoxConstraints childConstraints = constraints.widthConstraints().loosen();
     child.layout(childConstraints, parentUsesSize: true);
-
-    final double maxScale = child.size.width != 0.0
-      ? clampDouble(constraints.maxWidth / child.size.width, 1.0, 1.1)
-      : 1.1;
-    _scale = clampDouble(
-      1.0 + (constraints.maxHeight - (_kNavBarLargeTitleHeightExtension - _kNavBarBottomPadding)) / (_kNavBarLargeTitleHeightExtension - _kNavBarBottomPadding) * 0.03,
-      1.0,
-      maxScale,
-    );
-
-    childSize = child.size * _scale;
+    _scale = _computeTitleScale(child.size, constraints);
     final BoxParentData childParentData = child.parentData! as BoxParentData;
-    childParentData.offset = alignment.alongOffset(size - childSize as Offset);
+    childParentData.offset = alignment.alongOffset(size - (child.size * _scale) as Offset);
   }
 
   @override

packages/flutter/lib/src/cupertino/segmented_control.dart

@@ -626,6 +626,18 @@ class _RenderSegmentedControl<T> extends RenderBox
     return constraints.constrain(Size(childSize.width * childCount, childSize.height));
   }
 
+  @override
+  double? computeDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) {
+    final Size childSize = _calculateChildSize(constraints);
+    final BoxConstraints childConstraints = BoxConstraints.tight(childSize);
+
+    BaselineOffset baselineOffset = BaselineOffset.noBaseline;
+    for (RenderBox? child = firstChild; child != null; child = childAfter(child)) {
+      baselineOffset = baselineOffset.minOf(BaselineOffset(child.getDryBaseline(childConstraints, baseline)));
+    }
+    return baselineOffset.offset;
+  }
+
   @override
   Size computeDryLayout(BoxConstraints constraints) {
     final Size childSize = _calculateChildSize(constraints);

packages/flutter/lib/src/cupertino/sliding_segmented_control.dart

@@ -947,6 +947,18 @@ class _RenderSegmentedControl<T> extends RenderBox
     return constraints.constrain(Size(childSize.width * childCount + totalSeparatorWidth, childSize.height));
   }
 
+  @override
+  double? computeDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) {
+    final Size childSize = _calculateChildSize(constraints);
+    final BoxConstraints childConstraints = BoxConstraints.tight(childSize);
+
+    BaselineOffset baselineOffset = BaselineOffset.noBaseline;
+    for (RenderBox? child = firstChild; child != null; child = childAfter(child)) {
+      baselineOffset = baselineOffset.minOf(BaselineOffset(child.getDryBaseline(childConstraints, baseline)));
+    }
+    return baselineOffset.offset;
+  }
+
   @override
   Size computeDryLayout(BoxConstraints constraints) {
     final Size childSize = _calculateChildSize(constraints);

packages/flutter/lib/src/cupertino/text_selection_toolbar.dart

@@ -276,7 +276,30 @@ class _RenderCupertinoTextSelectionToolbarShape extends RenderShiftedBox {
     markNeedsPaint();
   }
 
-  bool get isAbove => anchorAbove.dy >= (child?.size.height ?? 0.0) - _kToolbarArrowSize.height * 2;
+  bool _isAbove(double childHeight) => anchorAbove.dy >= childHeight - _kToolbarArrowSize.height * 2;
+
+  BoxConstraints _constraintsForChild(BoxConstraints constraints) {
+    return BoxConstraints(
+      minWidth: _kToolbarArrowSize.width + _kToolbarBorderRadius.x * 2,
+    ).enforce(constraints.loosen());
+  }
+
+  Offset _computeChildOffset(Size childSize) {
+    return Offset(0.0, _isAbove(childSize.height) ? -_kToolbarArrowSize.height : 0.0);
+  }
+
+  @override
+  double? computeDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) {
+    final RenderBox? child = this.child;
+    if (child == null) {
+      return null;
+    }
+    final BoxConstraints enforcedConstraint = _constraintsForChild(constraints);
+    final double? result = child.getDryBaseline(enforcedConstraint, baseline);
+    return result == null
+      ? null
+      : result + _computeChildOffset(child.getDryLayout(enforcedConstraint)).dy;
+  }
 
   @override
   void performLayout() {
@@ -285,22 +308,15 @@ class _RenderCupertinoTextSelectionToolbarShape extends RenderShiftedBox {
       return;
     }
 
-    final BoxConstraints enforcedConstraint = BoxConstraints(
-      minWidth: _kToolbarArrowSize.width + _kToolbarBorderRadius.x * 2,
-    ).enforce(constraints.loosen());
-    child.layout(enforcedConstraint, parentUsesSize: true);
-
+    child.layout(_constraintsForChild(constraints), parentUsesSize: true);
     // The buttons are padded on both top and bottom sufficiently to have
     // the arrow clipped out of it on either side. By
     // using this approach, the buttons don't need any special padding that
     // depends on isAbove.
     // The height of one arrow will be clipped off of the child, so adjust the
     // size and position to remove that piece from the layout.
     final BoxParentData childParentData = child.parentData! as BoxParentData;
-    childParentData.offset = Offset(
-      0.0,
-      isAbove ? -_kToolbarArrowSize.height : 0.0,
-    );
+    childParentData.offset = _computeChildOffset(child.size);
     size = Size(
       child.size.width,
       child.size.height - _kToolbarArrowSize.height,
@@ -362,6 +378,7 @@ class _RenderCupertinoTextSelectionToolbarShape extends RenderShiftedBox {
       return path..addRRect(rrect);
     }
 
+    final bool isAbove = _isAbove(child.size.height);
     final Offset localAnchor = globalToLocal(isAbove ? _anchorAbove : _anchorBelow);
     final double arrowTipX = clampDouble(
       localAnchor.dx,

packages/flutter/test/cupertino/list_tile_test.dart

@@ -450,7 +450,7 @@ void main() {
       final Offset foundTitle = tester.getTopLeft(find.text('CupertinoListTile'));
       final Offset foundInfo = tester.getTopRight(find.text('Not Connected'));
 
-      expect(foundTitle.dx > foundInfo.dx, isTrue);
+      expect(foundTitle.dx, greaterThanOrEqualTo(foundInfo.dx));
     });
 
     testWidgets('trailing is on the left of additionalInfo', (WidgetTester tester) async {
@@ -476,7 +476,7 @@ void main() {
       final Offset foundInfo = tester.getTopLeft(find.text('Not Connected'));
       final Offset foundTrailing = tester.getTopRight(find.byType(CupertinoListTileChevron));
 
-      expect(foundInfo.dx > foundTrailing.dx, isTrue);
+      expect(foundInfo.dx, greaterThanOrEqualTo(foundTrailing.dx));
     });
   });