From 53c751b5140460b75fc3faa256707f44522ff3b8 Mon Sep 17 00:00:00 2001
From: Honghao Zhang <m@honghao.dev>
Date: Sun, 15 Sep 2024 12:07:13 -0700
Subject: [PATCH] [graphics] add CGPath transform

---
 .../Universal/Graphics/CGPath+Transform.swift | 31 +++++++++++++------
 .../Graphics/CGPath+TransformTests.swift      | 25 +++++++++++++--
 2 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/Sources/ChouTiUI/Universal/Graphics/CGPath+Transform.swift b/Sources/ChouTiUI/Universal/Graphics/CGPath+Transform.swift
index f457358..4fe3855 100644
--- a/Sources/ChouTiUI/Universal/Graphics/CGPath+Transform.swift
+++ b/Sources/ChouTiUI/Universal/Graphics/CGPath+Transform.swift
@@ -156,32 +156,43 @@ public extension CGPath {
     return resizedPath
   }
 
+  // MARK: - Transform
+
+  /// Creates an new immutable copy of the path transformed by a transformation matrix.
+  ///
+  /// - Parameters:
+  ///   - transform: The transform to apply to the path.
+  /// - Returns: A new, immutable transformed path.
+  func transform(_ transform: CGAffineTransform) -> CGPath {
+    var transform = transform
+    guard let transformedPath = copy(using: &transform) else {
+      ChouTi.assertFailure("Failed to transform the path", metadata: ["path": "\(self)", "transform": "\(transform)"])
+      return self
+    }
+    return transformedPath
+  }
+
   // MARK: - Translate
 
-  /// Translate the path.
+  /// Creates an new immutable copy of the path translated by a certain offset.
   ///
   /// - Parameters:
   ///   - point: The point represents the offset to translate the path by.
-  /// - Returns: A translated path.
+  /// - Returns: A new, immutable translated path.
   @inlinable
   @inline(__always)
   func translate(_ point: CGPoint) -> CGPath {
     translate(dx: point.x, dy: point.y)
   }
 
-  /// Translate the path by a certain offset.
+  /// Creates an new immutable copy of the path translated by a certain offset.
   ///
   /// - Parameters:
   ///   - dx: The x-coordinate offset.
   ///   - dy: The y-coordinate offset.
-  /// - Returns: A translated path.
+  /// - Returns: A new, immutable translated path.
   func translate(dx: CGFloat = 0, dy: CGFloat = 0) -> CGPath {
-    var transform = CGAffineTransform.translation(x: dx, y: dy)
-    guard let translatedPath = copy(using: &transform) else {
-      ChouTi.assertFailure("Fail to translate the path", metadata: ["path": "\(self)", "dx": "\(dx)", "dy": "\(dy)"])
-      return self
-    }
-    return translatedPath
+    transform(CGAffineTransform.translation(x: dx, y: dy))
   }
 }
 
diff --git a/Tests/ChouTiUITests/Universal/Graphics/CGPath+TransformTests.swift b/Tests/ChouTiUITests/Universal/Graphics/CGPath+TransformTests.swift
index ab40694..829c94c 100644
--- a/Tests/ChouTiUITests/Universal/Graphics/CGPath+TransformTests.swift
+++ b/Tests/ChouTiUITests/Universal/Graphics/CGPath+TransformTests.swift
@@ -268,6 +268,27 @@ class CGPath_TransformTests: XCTestCase {
     Assert.resetTestAssertionFailureHandler()
   }
 
+  // MARK: - Transform
+
+  func test_transform_identity() {
+    let rect = CGRect(x: 10, y: 20, width: 100, height: 50)
+    let path = CGPath(rect: rect, transform: nil)
+
+    let transformedPath = path.transform(CGAffineTransform.identity)
+    expect(transformedPath) == path
+  }
+
+  func test_transform_scale() {
+    let rect = CGRect(x: 10, y: 20, width: 100, height: 50)
+    let path = CGPath(ellipseIn: rect, transform: nil)
+
+    var scale = CGAffineTransform.scale(2, 2)
+    let transformedPath = path.transform(scale)
+    expect(transformedPath) == CGPath(ellipseIn: rect, transform: &scale)
+    print(transformedPath.boundingBoxOfPath)
+    expect(transformedPath) == CGPath(ellipseIn: CGRect(x: 20, y: 40, width: 200, height: 100), transform: nil)
+  }
+
   // MARK: - Translate
 
   func test_translate_point() {
@@ -318,8 +339,8 @@ class CGPath_TransformTests: XCTestCase {
     let dy: CGFloat = .nan
 
     Assert.setTestAssertionFailureHandler { message, metadata, file, line, column in
-      expect(message) == "Fail to translate the path"
-      expect(metadata) == ["path": "\(path)", "dx": "\(dx)", "dy": "\(dy)"]
+      expect(message) == "Failed to transform the path"
+      expect(metadata) == ["path": "\(path)", "transform": "\(CGAffineTransform.translation(dx, dy))"]
     }
 
     let translatedPath = path.translate(dx: dx, dy: dy)