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Merge pull request #26 from PureSwift/feature/text-styling
Text styling modifiers
2 parents cc60c6a + 35a552e commit f63a2d5

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‎AndroidSwiftUICore/Sources/AndroidSwiftUICore/Modifiers/TextModifiers.swift‎

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//
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// TextModifiers.swift
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// AndroidSwiftUICore
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//
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// Text-styling modifiers. Unlike layout modifiers (padding, background…) that
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// fold into the Compose `Modifier` chain, these describe attributes of the
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// `Text` composable itself; the interpreter reads their kinds off a Text
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// node's modifier chain and applies them as `Text(...)` parameters.
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//
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// MARK: - Font
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/// A font: either a named text style (resolved to a size by the interpreter)
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/// or an explicit system size, with an optional weight.
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public struct Font: Equatable, Sendable {
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internal var style: String?
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internal var size: Double?
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internal var weight: Weight?
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internal init(style: String? = nil, size: Double? = nil, weight: Weight? = nil) {
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self.style = style
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self.size = size
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self.weight = weight
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}
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public enum Weight: String, Equatable, Sendable {
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case ultraLight, thin, light, regular, medium, semibold, bold, heavy, black
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}
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public static let largeTitle = Font(style: "largeTitle")
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public static let title = Font(style: "title")
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public static let title2 = Font(style: "title2")
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public static let title3 = Font(style: "title3")
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public static let headline = Font(style: "headline")
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public static let subheadline = Font(style: "subheadline")
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public static let body = Font(style: "body")
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public static let callout = Font(style: "callout")
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public static let footnote = Font(style: "footnote")
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public static let caption = Font(style: "caption")
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public static let caption2 = Font(style: "caption2")
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public static func system(size: Double, weight: Weight? = nil) -> Font {
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Font(size: size, weight: weight)
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}
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public func weight(_ weight: Weight) -> Font {
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var copy = self
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copy.weight = weight
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return copy
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}
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public func bold() -> Font { weight(.bold) }
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}
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public struct _FontModifier: RenderModifier {
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let font: Font
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public var _modifierNode: ModifierNode {
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var args: [String: PropValue] = [:]
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if let style = font.style { args["style"] = .string(style) }
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if let size = font.size { args["size"] = .double(size) }
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if let weight = font.weight { args["weight"] = .string(weight.rawValue) }
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return ModifierNode(kind: "font", args: args)
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}
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}
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public extension View {
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func font(_ font: Font) -> ModifiedContent<Self, _FontModifier> {
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modifier(_FontModifier(font: font))
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}
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}
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// MARK: - Foreground color
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public struct _ForegroundColorModifier: RenderModifier {
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let color: Color
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public var _modifierNode: ModifierNode {
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ModifierNode(kind: "foregroundColor", args: ["color": color.propValue])
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}
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}
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public extension View {
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func foregroundColor(_ color: Color) -> ModifiedContent<Self, _ForegroundColorModifier> {
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modifier(_ForegroundColorModifier(color: color))
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}
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func foregroundStyle(_ color: Color) -> ModifiedContent<Self, _ForegroundColorModifier> {
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modifier(_ForegroundColorModifier(color: color))
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}
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}
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// MARK: - Weight
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public struct _FontWeightModifier: RenderModifier {
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let weight: Font.Weight
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public var _modifierNode: ModifierNode {
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ModifierNode(kind: "fontWeight", args: ["weight": .string(weight.rawValue)])
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}
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}
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public extension View {
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func fontWeight(_ weight: Font.Weight) -> ModifiedContent<Self, _FontWeightModifier> {
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modifier(_FontWeightModifier(weight: weight))
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}
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func bold() -> ModifiedContent<Self, _FontWeightModifier> {
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modifier(_FontWeightModifier(weight: .bold))
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}
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}
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// MARK: - Italic
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public struct _ItalicModifier: RenderModifier {
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public var _modifierNode: ModifierNode { ModifierNode(kind: "italic") }
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}
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public extension View {
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func italic() -> ModifiedContent<Self, _ItalicModifier> {
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modifier(_ItalicModifier())
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}
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}
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// MARK: - Line limit
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public struct _LineLimitModifier: RenderModifier {
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let limit: Int?
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public var _modifierNode: ModifierNode {
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var args: [String: PropValue] = [:]
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if let limit { args["count"] = .int(limit) }
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return ModifierNode(kind: "lineLimit", args: args)
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}
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}
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public extension View {
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func lineLimit(_ number: Int?) -> ModifiedContent<Self, _LineLimitModifier> {
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modifier(_LineLimitModifier(limit: number))
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}
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}
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// MARK: - Multiline text alignment
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public enum TextAlignment: String, Equatable, Sendable {
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case leading, center, trailing
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}
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public struct _MultilineTextAlignmentModifier: RenderModifier {
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let alignment: TextAlignment
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public var _modifierNode: ModifierNode {
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ModifierNode(kind: "multilineTextAlignment", args: ["value": .string(alignment.rawValue)])
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}
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}
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public extension View {
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func multilineTextAlignment(_ alignment: TextAlignment) -> ModifiedContent<Self, _MultilineTextAlignmentModifier> {
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modifier(_MultilineTextAlignmentModifier(alignment: alignment))
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}
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}

‎AndroidSwiftUICore/Tests/AndroidSwiftUICoreTests/EvaluatorTests.swift‎

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#expect(frame?.args["width"] == .double(100))
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#expect(frame?.args["height"] == .double(50))
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}
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@Test("Named font emits its style")
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func fontStyle() {
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let node = ViewHost(Text("x").font(.headline)).evaluate()
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let font = node.modifiers.first { $0.kind == "font" }
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#expect(font?.args["style"] == .string("headline"))
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#expect(font?.args["size"] == nil)
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}
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@Test("System font emits size and weight")
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func systemFont() {
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let node = ViewHost(Text("x").font(.system(size: 24, weight: .heavy))).evaluate()
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let font = node.modifiers.first { $0.kind == "font" }
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#expect(font?.args["size"] == .double(24))
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#expect(font?.args["weight"] == .string("heavy"))
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}
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@Test("foregroundColor emits an argb color")
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func foregroundColor() {
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let node = ViewHost(Text("x").foregroundColor(.red)).evaluate()
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let color = node.modifiers.first { $0.kind == "foregroundColor" }
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#expect(color?.args["color"] == Color.red.propValue)
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}
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@Test("bold and italic emit their kinds")
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func boldItalic() {
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let node = ViewHost(Text("x").bold().italic()).evaluate()
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let weight = node.modifiers.first { $0.kind == "fontWeight" }
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#expect(weight?.args["weight"] == .string("bold"))
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#expect(node.modifiers.contains { $0.kind == "italic" })
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}
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@Test("lineLimit emits its count")
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func lineLimit() {
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let node = ViewHost(Text("x").lineLimit(2)).evaluate()
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let limit = node.modifiers.first { $0.kind == "lineLimit" }
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#expect(limit?.args["count"] == .int(2))
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}
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}

‎Demo/App.swiftpm/Sources/ControlPlaygrounds.swift‎

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Example("Verbatim") { Text(verbatim: "Raw string, no interpolation") }
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Example("Interpolated") { Text("Counter is \(counter)") }
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Example("Bump the counter") { Button("Increment") { counter += 1 } }
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Example("Font sizes") {
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VStack(alignment: .leading, spacing: 4) {
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Text("Large title").font(.largeTitle)
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Text("Title").font(.title)
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Text("Headline").font(.headline)
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Text("Body").font(.body)
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Text("Caption").font(.caption)
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}
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}
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Example("Weight & style") {
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VStack(alignment: .leading, spacing: 4) {
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Text("Bold").bold()
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Text("Semibold").fontWeight(.semibold)
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Text("Italic").italic()
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Text("System 24 heavy").font(.system(size: 24, weight: .heavy))
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}
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}
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Example("Colors") {
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VStack(alignment: .leading, spacing: 4) {
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Text("Red").foregroundColor(.red)
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Text("Blue").foregroundColor(.blue)
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Text("Green, bold, title").font(.title).bold().foregroundColor(.green)
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}
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}
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Example("Line limit") {
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Text("A longer passage of text that wraps onto multiple lines, capped at two by lineLimit so the rest is truncated.")
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.lineLimit(2)
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}
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Example("Multiline") {
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Text("A longer passage of text that wraps onto multiple lines when it no longer fits within the width of the screen.")
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}
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Example("Styled") {
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Text("Blue on a rounded chip")
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.foregroundColor(.white)
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.padding()
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.background(Color.blue)
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.cornerRadius(12)

‎Demo/swiftui/src/commonMain/kotlin/com/pureswift/swiftui/Render.kt‎

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import androidx.compose.ui.draw.rotate
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import androidx.compose.ui.draw.scale
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import androidx.compose.ui.graphics.Color
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import androidx.compose.ui.text.font.FontStyle
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import androidx.compose.ui.text.font.FontWeight
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import androidx.compose.ui.text.style.TextAlign
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import androidx.compose.ui.text.input.TextFieldValue
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import androidx.compose.ui.unit.TextUnit
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import androidx.compose.ui.unit.sp
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import androidx.compose.ui.unit.IntOffset
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import androidx.compose.ui.unit.dp
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import androidx.compose.foundation.layout.fillMaxWidth
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fun Render(node: ViewNode) {
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key(node.id) {
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when (node.type) {
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"Text" -> Text(
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text = node.string("text") ?: "",
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modifier = node.composeModifiers(),
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)
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"Text" -> RenderText(node)
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"Button" -> {
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val onTap = node.long("onTap")
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}
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}
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// Text-styling modifiers describe attributes of the Text composable itself,
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// not the layout Modifier chain, so they are read off the node here and passed
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// as `Text(...)` parameters. Later (innermost) entries win for scalar
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// attributes. Layout modifiers in the same chain still apply via composeModifiers().
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@Composable
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private fun RenderText(node: ViewNode) {
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var color = Color.Unspecified
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var fontSize: TextUnit = TextUnit.Unspecified
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var weight: FontWeight? = null
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var fontStyle: FontStyle? = null
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var maxLines = Int.MAX_VALUE
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var textAlign: TextAlign? = null
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for (m in node.modifiers) {
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when (m.kind) {
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"font" -> {
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m.args.string("style")?.let { style ->
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fontSize = fontSizeForStyle(style).sp
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if (weight == null) weight = defaultWeightForStyle(style)
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}
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m.args.double("size")?.let { fontSize = it.sp }
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m.args.string("weight")?.let { weight = fontWeightFor(it) }
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}
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"fontWeight" -> m.args.string("weight")?.let { weight = fontWeightFor(it) }
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"italic" -> fontStyle = FontStyle.Italic
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"foregroundColor" -> m.args.long("color")?.let { color = Color(it.toInt()) }
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"lineLimit" -> maxLines = m.args.long("count")?.toInt() ?: Int.MAX_VALUE
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"multilineTextAlignment" -> textAlign = when (m.args.string("value")) {
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"leading" -> TextAlign.Start
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"trailing" -> TextAlign.End
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else -> TextAlign.Center
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}
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}
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}
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Text(
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text = node.string("text") ?: "",
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color = color,
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fontSize = fontSize,
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fontWeight = weight,
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fontStyle = fontStyle,
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maxLines = maxLines,
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textAlign = textAlign,
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modifier = node.composeModifiers(),
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)
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}
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// SwiftUI named text styles → point sizes (Compose has no built-in analog).
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private fun fontSizeForStyle(style: String): Double = when (style) {
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"largeTitle" -> 34.0
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"title" -> 28.0
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"title2" -> 22.0
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"title3" -> 20.0
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"headline" -> 17.0
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"body" -> 17.0
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"callout" -> 16.0
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"subheadline" -> 15.0
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"footnote" -> 13.0
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"caption" -> 12.0
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"caption2" -> 11.0
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else -> 17.0
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}
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// Only headline carries a non-regular default weight in SwiftUI.
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private fun defaultWeightForStyle(style: String): FontWeight? =
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if (style == "headline") FontWeight.SemiBold else null
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private fun fontWeightFor(name: String): FontWeight = when (name) {
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"ultraLight" -> FontWeight.ExtraLight
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"thin" -> FontWeight.Thin
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"light" -> FontWeight.Light
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"regular" -> FontWeight.Normal
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"medium" -> FontWeight.Medium
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"semibold" -> FontWeight.SemiBold
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"bold" -> FontWeight.Bold
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"heavy" -> FontWeight.ExtraBold
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"black" -> FontWeight.Black
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else -> FontWeight.Normal
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}
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/// Folds a node's ordered modifier chain into a Compose `Modifier`.
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/// The chain arrives outermost-first, which is exactly Compose's order.
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internal fun ViewNode.composeModifiers(): Modifier {

‎Demo/swiftui/src/commonMain/kotlin/com/pureswift/swiftui/ViewNode.kt‎

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internal fun JsonObject.double(key: String): Double? = (this[key] as? JsonPrimitive)?.doubleOrNull
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internal fun JsonObject.long(key: String): Long? = (this[key] as? JsonPrimitive)?.longOrNull
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internal fun JsonObject.string(key: String): String? = (this[key] as? JsonPrimitive)?.content

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