Little bit of rect helper

Author: andyfinnell

Sources/BaseKit/Geometry/Rect.swift

@@ -51,6 +51,36 @@ public struct Rect: Hashable, Codable, Sendable {
         origin.isClose(to: other.origin, threshold: threshold)
         && size.isClose(to: other.size, threshold: threshold)
     }
+    
+    public func insetBy(dx: Real, dy: Real) -> Rect {
+        Rect(
+            x: minX + dx,
+            y: minY + dy,
+            width: width - 2.0 * dx,
+            height: height - 2.0 * dy
+        )
+    }
+    
+    public func offsetBy(dx: Real, dy: Real) -> Rect {
+        Rect(
+            x: minX + dx,
+            y: minY + dy,
+            width: width,
+            height: height
+        )
+    }
+    
+    public func center(inside biggerRect: Rect) -> Rect {
+        let dx = (biggerRect.width - width) / 2.0
+        let dy = (biggerRect.height - height) / 2.0
+        return offsetBy(dx: dx, dy: dy)
+    }
+    
+    public func center(on insideRect: Rect) -> Rect {
+        let dx = (width - insideRect.width) / 2.0
+        let dy = (height - insideRect.height) / 2.0
+        return offsetBy(dx: -dx, dy: -dy)
+    }
 }
 
 public extension Optional where Wrapped == Rect {

Tests/BaseKitTests/Geometry/RectTests.swift

@@ -0,0 +1,25 @@
+import BaseKit
+import Testing
+
+
+struct RectTests {
+    @Test
+    func testInset() {
+        let subject = Rect(x: 25, y: 60, width: 100, height: 70)
+        #expect(subject.insetBy(dx: 25, dy: 10) == Rect(x: 50, y: 70, width: 50, height: 50))
+    }
+    
+    @Test
+    func testCenterInside() {
+        let containingRect = Rect(x: 25, y: 50, width: 100, height: 50)
+        let subject = Rect(x: 25, y: 50, width: 50, height: 50)
+        #expect(subject.center(inside: containingRect) == Rect(x: 50, y: 50, width: 50, height: 50))
+    }
+    
+    @Test
+    func testCenterOn() {
+        let containedRect = Rect(x: 25, y: 50, width: 50, height: 50)
+        let subject = Rect(x: 25, y: 50, width: 100, height: 50)
+        #expect(subject.center(on: containedRect) == Rect(x: 0, y: 50, width: 100, height: 50))
+    }
+}