From 6ff02dbc83bea984c8f84cd269030d75c8f8ba25 Mon Sep 17 00:00:00 2001
From: Maximilian Fischer <github@maaeps.de>
Date: Wed, 11 Oct 2023 19:39:56 +0200
Subject: [PATCH] Include size factors when computing the intrinsic size of a
 `RenderPositionedBox` (#135823)

This PR includes the `widthFactor` and `heightFactor` when computing the intrinsic size of a `RenderPositionedBox`.

<details><summary>Code sample</summary>

Red should have a height of 100, blue one of 200.

```dart
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Intrinsic Bug',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: Scaffold(
        body: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Expanded(
              child: IntrinsicHeight(
                child: Align(
                  heightFactor: 0.5,
                  child: Container(
                    height: 200,
                    color: Colors.red,
                  ),
                ),
              ),
            ),
            Expanded(
              child: Container(
                height: 200,
                color: Colors.blue,
              ),
            ),
          ],
        ),
      ),
    );
  }
}
```
</details>

Before:
![grafik](https://github.com/flutter/flutter/assets/45403027/447d8b9b-e7f3-482a-900d-53e436830321)
After:
![grafik](https://github.com/flutter/flutter/assets/45403027/6d1a104b-3327-47e2-8b36-798ed0136793)

Fix #135822
---
 .../lib/src/rendering/shifted_box.dart        | 20 +++++++++++++++++++
 .../test/rendering/positioned_box_test.dart   | 12 +++++++++++
 2 files changed, 32 insertions(+)

diff --git a/packages/flutter/lib/src/rendering/shifted_box.dart b/packages/flutter/lib/src/rendering/shifted_box.dart
index 2afe15c064..85de3a16cd 100644
--- a/packages/flutter/lib/src/rendering/shifted_box.dart
+++ b/packages/flutter/lib/src/rendering/shifted_box.dart
@@ -407,6 +407,26 @@ class RenderPositionedBox extends RenderAligningShiftedBox {
     markNeedsLayout();
   }
 
+  @override
+  double computeMinIntrinsicWidth(double height) {
+    return super.computeMinIntrinsicWidth(height) * (_widthFactor ?? 1);
+  }
+
+  @override
+  double computeMaxIntrinsicWidth(double height) {
+    return super.computeMaxIntrinsicWidth(height) * (_widthFactor ?? 1);
+  }
+
+  @override
+  double computeMinIntrinsicHeight(double width) {
+    return super.computeMinIntrinsicHeight(width)  * (_heightFactor ?? 1);
+  }
+
+  @override
+  double computeMaxIntrinsicHeight(double width) {
+    return super.computeMaxIntrinsicHeight(width)  * (_heightFactor ?? 1);
+  }
+
   @override
   Size computeDryLayout(BoxConstraints constraints) {
     final bool shrinkWrapWidth = _widthFactor != null || constraints.maxWidth == double.infinity;
diff --git a/packages/flutter/test/rendering/positioned_box_test.dart b/packages/flutter/test/rendering/positioned_box_test.dart
index f41613bdc4..e47709c2e8 100644
--- a/packages/flutter/test/rendering/positioned_box_test.dart
+++ b/packages/flutter/test/rendering/positioned_box_test.dart
@@ -55,6 +55,10 @@ void main() {
     final RenderPositionedBox positioner = RenderPositionedBox(child: sizer, widthFactor: 1.0, heightFactor: 0.0);
     layout(positioner, constraints: BoxConstraints.loose(const Size(200.0, 200.0)));
 
+    expect(positioner.computeMinIntrinsicWidth(200), equals(100.0));
+    expect(positioner.computeMaxIntrinsicWidth(200), equals(100.0));
+    expect(positioner.computeMinIntrinsicHeight(200), equals(0));
+    expect(positioner.computeMaxIntrinsicHeight(200), equals(0));
     expect(positioner.size.width, equals(100.0));
     expect(positioner.size.height, equals(0.0));
 
@@ -62,6 +66,10 @@ void main() {
     positioner.heightFactor = 0.5;
     pumpFrame();
 
+    expect(positioner.computeMinIntrinsicWidth(200), equals(50.0));
+    expect(positioner.computeMaxIntrinsicWidth(200), equals(50.0));
+    expect(positioner.computeMinIntrinsicHeight(200), equals(50.0));
+    expect(positioner.computeMaxIntrinsicHeight(200), equals(50.0));
     expect(positioner.size.width, equals(50.0));
     expect(positioner.size.height, equals(50.0));
 
@@ -69,6 +77,10 @@ void main() {
     positioner.heightFactor = null;
     pumpFrame();
 
+    expect(positioner.computeMinIntrinsicWidth(200), equals(100.0));
+    expect(positioner.computeMaxIntrinsicWidth(200), equals(100.0));
+    expect(positioner.computeMinIntrinsicHeight(200), equals(100.0));
+    expect(positioner.computeMaxIntrinsicHeight(200), equals(100.0));
     expect(positioner.size.width, equals(200.0));
     expect(positioner.size.height, equals(200.0));
   });