Update sizeThatFits to check each axis' constraint separately

BlueprintUI/Sources/Blueprint View/BlueprintView.swift

@@ -75,16 +75,43 @@ public final class BlueprintView: UIView {
         fatalError("init(coder:) has not been implemented")
     }
 
-    /// Forwarded to the `measure(in:)` implementation of the root element.
+    ///
+    /// Measures the size needed to display the view within then given constraining size,
+    /// by measuring the current `element` of the `BlueprintView`.
+    ///
+    /// If you would like to not constrain the measurement in a given axis,
+    /// pass `0.0` or `.greatestFiniteMagnitude` for that axis, eg:
+    ///
+    /// ```
+    /// // Measures with a width of 100, and no height constraint.
+    /// blueprintView.sizeThatFits(CGSize(width: 100.0, height: 0.0))
+    ///
+    /// // Measures with a height of 100, and no width constraint.
+    /// blueprintView.sizeThatFits(CGSize(width: 0.0, height: 100.0))
+    ///
+    /// // Measures unconstrained in both axes.
+    /// blueprintView.sizeThatFits(.zero)
+    /// ```
+    ///
     override public func sizeThatFits(_ size: CGSize) -> CGSize {
-        guard let element = element else { return .zero }
-        let constraint: SizeConstraint
-        if size == .zero {
-            constraint = SizeConstraint(width: .unconstrained, height: .unconstrained)
-        } else {
-            constraint = SizeConstraint(size)
+        guard let element = element else {
+            return .zero
         }
-        return element.content.measure(in: constraint)
+
+        func measurementConstraint(with size : CGSize) -> SizeConstraint {
+
+            let unconstrainedValues : [CGFloat] = [0.0, .greatestFiniteMagnitude, .infinity]
+
+            let widthUnconstrained = unconstrainedValues.contains(size.width)
+            let heightUnconstrained = unconstrainedValues.contains(size.height)
+
+            return SizeConstraint(
+                width: widthUnconstrained ? .unconstrained : .atMost(size.width),
+                height: heightUnconstrained ? .unconstrained : .atMost(size.height)
+            )
+        }
+
+        return element.content.measure(in: measurementConstraint(with: size))
     }
 
     /// Returns the size of the element bound to the current width (mimicking

BlueprintUI/Tests/BlueprintViewTests.swift

@@ -2,6 +2,86 @@ import XCTest
 @testable import BlueprintUI
 
 class BlueprintViewTests: XCTestCase {
+
+    func test_sizeThatFits() {
+
+        /// NOTE: References to `.greatestFiniteMagnitude` always refer to the fully qualified type,
+        /// `CGFloat.greatestFiniteMagnitude` to ensure we are not implicitly comparing against doubles,
+        /// which have a different underlying type on 32 bit devices.
+
+        let blueprintView = BlueprintView()
+
+        // Normal sizes.
+
+        do {
+            let element = MeasurableElement { constraint in
+                XCTAssertEqual(constraint.maximum, CGSize(width: 200, height: 100))
+                return CGSize(width: 100, height: 50)
+            }
+
+            blueprintView.element = element
+
+            XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: 200, height: 100)), CGSize(width: 100, height: 50))
+        }
+
+        // Unconstrained in both axes.
+
+        do {
+            let element = MeasurableElement { constraint in
+                XCTAssertEqual(constraint.width, .unconstrained)
+                XCTAssertEqual(constraint.height, .unconstrained)
+                XCTAssertEqual(constraint.maximum, CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude))
+
+                return CGSize(width: 100, height: 50)
+            }
+
+            blueprintView.element = element
+
+            XCTAssertEqual(blueprintView.sizeThatFits(.zero), CGSize(width: 100, height: 50))
+            XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude)), CGSize(width: 100, height: 50))
+            XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: CGFloat.infinity, height: CGFloat.infinity)), CGSize(width: 100, height: 50))
+        }
+
+        // Unconstrained in one axis only.
+
+        do {
+            // X
+
+            do {
+                let element = MeasurableElement { constraint in
+                    XCTAssertEqual(constraint.width, .unconstrained)
+                    XCTAssertEqual(constraint.height.maximum, 100.0)
+                    XCTAssertEqual(constraint.maximum, CGSize(width: CGFloat.greatestFiniteMagnitude, height: 100.0))
+
+                    return CGSize(width: 100, height: 50)
+                }
+
+                blueprintView.element = element
+
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: 0.0, height: 100.0)), CGSize(width: 100, height: 50))
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: CGFloat.greatestFiniteMagnitude, height: 100.0)), CGSize(width: 100, height: 50))
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: CGFloat.infinity, height: 100.0)), CGSize(width: 100, height: 50))
+            }
+
+            // Y
+
+            do {
+                let element = MeasurableElement { constraint in
+                    XCTAssertEqual(constraint.width.maximum, 100.0)
+                    XCTAssertEqual(constraint.height, .unconstrained)
+                    XCTAssertEqual(constraint.maximum, CGSize(width: 100.0, height: CGFloat.greatestFiniteMagnitude))
+
+                    return CGSize(width: 100, height: 50)
+                }
+
+                blueprintView.element = element
+
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: 100.0, height: 0.0)), CGSize(width: 100, height: 50))
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: 100.0, height: CGFloat.greatestFiniteMagnitude)), CGSize(width: 100, height: 50))
+                XCTAssertEqual(blueprintView.sizeThatFits(CGSize(width: 100.0, height: CGFloat.infinity)), CGSize(width: 100, height: 50))
+            }
+        }
+    }
 
     func test_displaysSimpleView() {
 
@@ -63,6 +143,20 @@ class BlueprintViewTests: XCTestCase {
 
 }
 
+fileprivate struct MeasurableElement : Element {
+
+    var validate : (SizeConstraint) -> CGSize
+
+    var content: ElementContent {
+        ElementContent {
+            self.validate($0)
+        }
+    }
+
+    func backingViewDescription(bounds: CGRect, subtreeExtent: CGRect?) -> ViewDescription? {
+        return nil
+    }
+}
 
 fileprivate struct SimpleViewElement: Element {
 

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - [Fixed `ConstrainedSize`](https://github.com/square/Blueprint/pull/87) to ensure that the measurement of its inner element respects the `ConstrainedSize`'s maximum size, which matters for measuring elements which re-flow based on width, such as elements containing text.
 
+- Changed [BlueprintView.sizeThatFits(:)](https://github.com/square/Blueprint/pull/92/files) to treat width and height separately when determining if measurement should be unconstrained in a given axis.
+
 ### Added
 
 - [Added support](https://github.com/square/Blueprint/pull/88) for `SwiftUI`-style element building within `BlueprintUI` and `BlueprintUICommonControls`.

SampleApp/SampleApp.xcodeproj/project.pbxproj

@@ -9,6 +9,9 @@
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+		0AF36345246266AF0027E172 /* README.md in Resources */ = {isa = PBXBuildFile; fileRef = 0AF36342246266AF0027E172 /* README.md */; };
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+		0AF36347246266AF0027E172 /* CHANGELOG.md in Resources */ = {isa = PBXBuildFile; fileRef = 0AF36344246266AF0027E172 /* CHANGELOG.md */; };
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@@ -42,6 +45,9 @@
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 		0AEF0C4D24463B880092248C /* XcodePreviewDemo.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XcodePreviewDemo.swift; sourceTree = "<group>"; };
+		0AF36342246266AF0027E172 /* README.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; name = README.md; path = ../README.md; sourceTree = "<group>"; };
+		0AF36343246266AF0027E172 /* RELEASING.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; name = RELEASING.md; path = ../RELEASING.md; sourceTree = "<group>"; };
+		0AF36344246266AF0027E172 /* CHANGELOG.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; name = CHANGELOG.md; path = ../CHANGELOG.md; sourceTree = "<group>"; };
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@@ -141,6 +147,9 @@
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 				97545512223C12E9003E353F /* Resources */,
 				9754550F223C12E9003E353F /* Sources */,
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@@ -401,6 +410,9 @@
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