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leehericks wants to merge 3 commits into from
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Add length approximation from sampled points. #10

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26c57c3
Make inverting Y axis optional (with non-breaking default) (#9)
leehericks Dec 21, 2025
3f8802d
Add length approximation from sampled points.
leehericks Dec 21, 2025
069f7d9
Change extension from Array<SVGPoint> to Collection where Element == …
leehericks Dec 21, 2025
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4 changes: 2 additions & 2 deletions Sources/SVGPath+CoreGraphics.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,8 @@ import Foundation
// MARK: SVGPath to CGPath

public extension CGPath {
static func from(svgPath: String) throws -> CGPath {
try from(svgPath: SVGPath(string: svgPath))
static func from(svgPath: String, with options: SVGPath.ParseOptions = .default) throws -> CGPath {
try from(svgPath: SVGPath(string: svgPath, with: options))
}

static func from(svgPath: SVGPath) -> CGPath {
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74 changes: 55 additions & 19 deletions Sources/SVGPath.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -32,18 +32,29 @@
import Foundation

public struct SVGPath: Hashable, Sendable {
public struct ParseOptions: Sendable {
public static let `default` = Self()

public var invertYAxis: Bool

public init(invertYAxis: Bool = true) {
self.invertYAxis = invertYAxis
}
}

public var commands: [SVGCommand]

public init(commands: [SVGCommand]) {
self.commands = commands
}

public init(string: String) throws {
public init(string: String, with options: ParseOptions = .default) throws {
var token: UnicodeScalar = " "
var commands = [SVGCommand]()
var numbers = ArraySlice<Double>()
var number = ""
var isRelative = false
let yAxisSign = options.invertYAxis ? -1.0 : 1.0

func assertArgs(_ count: Int) throws -> [Double] {
if numbers.count < count {
Expand All @@ -57,19 +68,19 @@ public struct SVGPath: Hashable, Sendable {

func moveTo() throws -> SVGCommand {
let numbers = try assertArgs(2)
return .moveTo(SVGPoint(x: numbers[0], y: -numbers[1]))
return .moveTo(SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]))
}

func lineTo() throws -> SVGCommand {
let numbers = try assertArgs(2)
return .lineTo(SVGPoint(x: numbers[0], y: -numbers[1]))
return .lineTo(SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]))
}

func lineToVertical() throws -> SVGCommand {
let numbers = try assertArgs(1)
return .lineTo(SVGPoint(
x: isRelative ? 0 : commands.lastPoint.x,
y: -numbers[0]
y: yAxisSign * numbers[0]
))
}

Expand All @@ -84,8 +95,8 @@ public struct SVGPath: Hashable, Sendable {
func quadCurve() throws -> SVGCommand {
let numbers = try assertArgs(4)
return .quadratic(
SVGPoint(x: numbers[0], y: -numbers[1]),
SVGPoint(x: numbers[2], y: -numbers[3])
SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]),
SVGPoint(x: numbers[2], y: yAxisSign * numbers[3])
)
}

Expand All @@ -100,15 +111,15 @@ public struct SVGPath: Hashable, Sendable {
if !isRelative {
control += lastPoint
}
return .quadratic(control, SVGPoint(x: numbers[0], y: -numbers[1]))
return .quadratic(control, SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]))
}

func cubicCurve() throws -> SVGCommand {
let numbers = try assertArgs(6)
return .cubic(
SVGPoint(x: numbers[0], y: -numbers[1]),
SVGPoint(x: numbers[2], y: -numbers[3]),
SVGPoint(x: numbers[4], y: -numbers[5])
SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]),
SVGPoint(x: numbers[2], y: yAxisSign * numbers[3]),
SVGPoint(x: numbers[4], y: yAxisSign * numbers[5])
)
}

Expand All @@ -125,8 +136,8 @@ public struct SVGPath: Hashable, Sendable {
}
return .cubic(
control,
SVGPoint(x: numbers[0], y: -numbers[1]),
SVGPoint(x: numbers[2], y: -numbers[3])
SVGPoint(x: numbers[0], y: yAxisSign * numbers[1]),
SVGPoint(x: numbers[2], y: yAxisSign * numbers[3])
)
}

Expand All @@ -137,7 +148,7 @@ public struct SVGPath: Hashable, Sendable {
rotation: numbers[2] * .pi / 180,
largeArc: numbers[3] != 0,
sweep: numbers[4] != 0,
end: SVGPoint(x: numbers[5], y: -numbers[6])
end: SVGPoint(x: numbers[5], y: yAxisSign * numbers[6])
))
}

Expand Down Expand Up @@ -225,22 +236,29 @@ public extension SVGPath {
getPoints(&points, detail: detail)
return points
}

func length(withDetail detail: Int) -> Double {
return points(withDetail: detail).length
}

struct WriteOptions: Sendable {
public static let `default` = Self()

public var prettyPrinted: Bool
public var wrapWidth: Int
public var invertYAxis: Bool

public init(prettyPrinted: Bool = true, wrapWidth: Int = .max) {
public init(prettyPrinted: Bool = true, wrapWidth: Int = .max, invertYAxis: Bool = true) {
self.prettyPrinted = prettyPrinted
self.wrapWidth = wrapWidth
self.invertYAxis = invertYAxis
}
}

func string(with options: WriteOptions) -> String {
var output = ""
var width = 0
let yAxisSign = options.invertYAxis ? -1.0 : 1.0

func append(_ string: String) {
let spaced = width > 0 && (
Expand Down Expand Up @@ -269,19 +287,19 @@ public extension SVGPath {
for command in commands {
switch command {
case let .moveTo(point):
append("M", point.x, -point.y)
append("M", point.x, yAxisSign * point.y)
case let .lineTo(point):
append("L", point.x, -point.y)
append("L", point.x, yAxisSign * point.y)
case let .cubic(c1, c2, point):
append("C", c1.x, -c1.y, c2.x, -c2.y, point.x, -point.y)
append("C", c1.x, yAxisSign * c1.y, c2.x, yAxisSign * c2.y, point.x, yAxisSign * point.y)
case let .quadratic(control, point):
append("Q", control.x, -control.y, point.x, -point.y)
append("Q", control.x, yAxisSign * control.y, point.x, yAxisSign * point.y)
case let .arc(arc):
let rad = arc.radius, end = arc.end
let rot = arc.rotation / .pi * 180
let large = arc.largeArc ? 1.0 : 0
let sweep = arc.sweep ? 1.0 : 0
append("A", rad.x, rad.y, rot, large, sweep, end.x, -end.y)
append("A", rad.x, rad.y, rot, large, sweep, end.x, yAxisSign * end.y)
case .end:
append("Z")
}
Expand All @@ -290,6 +308,24 @@ public extension SVGPath {
}
}

public extension Collection where Element == SVGPoint {
var length: Double {
var it = makeIterator()
guard var prev = it.next() else { return 0 }

var total: Double = 0

while let p = it.next() {
let dx = Double(p.x - prev.x)
let dy = Double(p.y - prev.y)
total += (dx * dx + dy * dy).squareRoot()
prev = p
}

return total
}
}

private extension Character {
var isDigit: Bool {
isASCII && isWholeNumber
Expand Down
36 changes: 36 additions & 0 deletions Tests/SVGPathTests.swift
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Expand Up @@ -10,6 +10,42 @@ import SVGPath
import XCTest

class SVGPathTests: XCTestCase {
func testLineLength() throws {
let svgPath = try SVGPath(string: "M0 0 H100 V50")

let expected = 150.0
let measured = svgPath.length(withDetail: 32)

XCTAssertEqual(measured, expected, accuracy: 0.0)
}

func testArcLengthWithHalfCircle() throws {
let svgPath = try SVGPath(
string: "M100 0 A100 100 0 0 1 0 100 A100 100 0 0 1 -100 0"
)

let expected = Double.pi * 100
let measured = svgPath.length(withDetail: 32)
print("Measured: \(measured) Expected: \(expected)")

XCTAssertEqual(measured, expected, accuracy: 0.5)
}

func testTriangleWithoutInvertingYAxis() throws {
let parseOptions = SVGPath.ParseOptions(invertYAxis: false)
let svgPath = try SVGPath(string: "M150 0 L75 200 L225 200 Z", with: parseOptions)
let expected = SVGPath(commands: [
.moveTo(.init(x: 150, y: 0)),
.lineTo(.init(x: 75, y: 200)),
.lineTo(.init(x: 225, y: 200)),
.end,
])
XCTAssertEqual(svgPath, expected)

let writeOptions = SVGPath.WriteOptions(invertYAxis: false)
XCTAssertEqual(svgPath.string(with: writeOptions), "M150 0 L75 200 L225 200 Z")
}

func testTriangle() throws {
let svgPath = try SVGPath(string: "M150 0 L75 200 L225 200 Z")
let expected = SVGPath(commands: [
Expand Down