Use the environment's line spacing (#95)

* Set the environment's line spacing value to the attributed string paragraph style

* Refactor renderer environment

Author: gonzalezreal

Sources/MarkdownUI/Markdown.swift

@@ -119,12 +119,13 @@ public struct Markdown: View {
 
   private struct ViewState {
     var attributedString = NSAttributedString()
-    var environmentHash: Int?
+    var hashValue: Int?
   }
 
   @Environment(\.layoutDirection) private var layoutDirection: LayoutDirection
   @Environment(\.multilineTextAlignment) private var textAlignment: TextAlignment
   @Environment(\.sizeCategory) private var sizeCategory: ContentSizeCategory
+  @Environment(\.lineSpacing) private var lineSpacing: CGFloat
   @Environment(\.markdownStyle) private var style: MarkdownStyle
   @Environment(\.openMarkdownLink) private var openMarkdownLink
   @State private var viewState = ViewState()
@@ -194,35 +195,32 @@ public struct Markdown: View {
   }
 
   private var viewStatePublisher: AnyPublisher<ViewState, Never> {
-    struct Environment: Hashable {
-      var storage: Storage
-      var baseURL: URL?
-      var layoutDirection: LayoutDirection
-      var textAlignment: TextAlignment
-      var sizeCategory: ContentSizeCategory
-      var style: MarkdownStyle
+    struct Input: Hashable {
+      let storage: Storage
+      let environment: AttributedStringRenderer.Environment
     }
 
     return Just(
       // This value helps determine if we need to render the markdown again
-      Environment(
+      Input(
         storage: self.storage,
-        baseURL: self.baseURL,
-        layoutDirection: self.layoutDirection,
-        textAlignment: self.textAlignment,
-        sizeCategory: self.sizeCategory,
-        style: self.style
+        environment: .init(
+          baseURL: self.baseURL,
+          layoutDirection: self.layoutDirection,
+          alignment: self.textAlignment,
+          lineSpacing: self.lineSpacing,
+          sizeCategory: self.sizeCategory,
+          style: self.style
+        )
       ).hashValue
     )
-    .flatMap { environmentHash -> AnyPublisher<ViewState, Never> in
-      if self.viewState.environmentHash == environmentHash,
-        !viewState.attributedString.hasMarkdownImages
-      {
+    .flatMap { hashValue -> AnyPublisher<ViewState, Never> in
+      if self.viewState.hashValue == hashValue, !viewState.attributedString.hasMarkdownImages {
         return Empty().eraseToAnyPublisher()
-      } else if self.viewState.environmentHash == environmentHash {
-        return self.loadMarkdownImages(environmentHash: environmentHash)
+      } else if self.viewState.hashValue == hashValue {
+        return self.loadMarkdownImages(hashValue)
       } else {
-        return self.renderAttributedString(environmentHash: environmentHash)
+        return self.renderAttributedString(hashValue)
       }
     }
     .eraseToAnyPublisher()
@@ -235,29 +233,29 @@ public struct Markdown: View {
       }
   }
 
-  private func loadMarkdownImages(environmentHash: Int) -> AnyPublisher<ViewState, Never> {
+  private func loadMarkdownImages(_ hashValue: Int) -> AnyPublisher<ViewState, Never> {
     NSAttributedString.loadingMarkdownImages(
       from: self.viewState.attributedString,
       using: self.imageHandlers
     )
-    .map { ViewState(attributedString: $0, environmentHash: environmentHash) }
+    .map { ViewState(attributedString: $0, hashValue: hashValue) }
     .receive(on: UIScheduler.shared)
     .eraseToAnyPublisher()
   }
 
-  private func renderAttributedString(environmentHash: Int) -> AnyPublisher<ViewState, Never> {
+  private func renderAttributedString(_ hashValue: Int) -> AnyPublisher<ViewState, Never> {
     self.storage.document.renderAttributedString(
-      baseURL: self.baseURL,
-      baseWritingDirection: .init(self.layoutDirection),
-      alignment: .init(
+      environment: .init(
+        baseURL: self.baseURL,
         layoutDirection: self.layoutDirection,
-        textAlignment: self.textAlignment
+        alignment: self.textAlignment,
+        lineSpacing: self.lineSpacing,
+        sizeCategory: self.sizeCategory,
+        style: self.style
       ),
-      sizeCategory: self.sizeCategory,
-      style: self.style,
       imageHandlers: self.imageHandlers
     )
-    .map { ViewState(attributedString: $0, environmentHash: environmentHash) }
+    .map { ViewState(attributedString: $0, hashValue: hashValue) }
     .receive(on: UIScheduler.shared)
     .eraseToAnyPublisher()
   }
@@ -412,33 +410,3 @@ private struct OpenMarkdownLinkAction {
 private struct OpenMarkdownLinkKey: EnvironmentKey {
   static let defaultValue: OpenMarkdownLinkAction? = nil
 }
-
-extension NSWritingDirection {
-  fileprivate init(_ layoutDirection: LayoutDirection) {
-    switch layoutDirection {
-    case .leftToRight:
-      self = .leftToRight
-    case .rightToLeft:
-      self = .rightToLeft
-    @unknown default:
-      self = .natural
-    }
-  }
-}
-
-extension NSTextAlignment {
-  fileprivate init(layoutDirection: LayoutDirection, textAlignment: TextAlignment) {
-    switch (layoutDirection, textAlignment) {
-    case (_, .leading):
-      self = .natural
-    case (_, .center):
-      self = .center
-    case (.leftToRight, .trailing):
-      self = .right
-    case (.rightToLeft, .trailing):
-      self = .left
-    default:
-      self = .natural
-    }
-  }
-}

Sources/MarkdownUI/Rendering/AttributedStringRenderer+Environment.swift

@@ -0,0 +1,58 @@
+import SwiftUI
+
+extension AttributedStringRenderer {
+  struct Environment: Hashable {
+    let baseURL: URL?
+    let baseWritingDirection: NSWritingDirection
+    let alignment: NSTextAlignment
+    let lineSpacing: CGFloat
+    let sizeCategory: ContentSizeCategory
+    let style: MarkdownStyle
+
+    init(
+      baseURL: URL?,
+      layoutDirection: LayoutDirection,
+      alignment: TextAlignment,
+      lineSpacing: CGFloat,
+      sizeCategory: ContentSizeCategory,
+      style: MarkdownStyle
+    ) {
+      self.baseURL = baseURL
+      self.baseWritingDirection = .init(layoutDirection)
+      self.alignment = .init(layoutDirection, alignment)
+      self.lineSpacing = lineSpacing
+      self.sizeCategory = sizeCategory
+      self.style = style
+    }
+  }
+}
+
+extension NSWritingDirection {
+  fileprivate init(_ layoutDirection: LayoutDirection) {
+    switch layoutDirection {
+    case .leftToRight:
+      self = .leftToRight
+    case .rightToLeft:
+      self = .rightToLeft
+    @unknown default:
+      self = .natural
+    }
+  }
+}
+
+extension NSTextAlignment {
+  fileprivate init(_ layoutDirection: LayoutDirection, _ textAlignment: TextAlignment) {
+    switch (layoutDirection, textAlignment) {
+    case (_, .leading):
+      self = .natural
+    case (_, .center):
+      self = .center
+    case (.leftToRight, .trailing):
+      self = .right
+    case (.rightToLeft, .trailing):
+      self = .left
+    default:
+      self = .natural
+    }
+  }
+}

Sources/MarkdownUI/Rendering/AttributedStringRenderer.swift

@@ -36,19 +36,15 @@ struct AttributedStringRenderer {
     case decimal(Int)
   }
 
-  let baseURL: URL?
-  let baseWritingDirection: NSWritingDirection
-  let alignment: NSTextAlignment
-  let sizeCategory: ContentSizeCategory
-  let style: MarkdownStyle
+  let environment: Environment
 
   func renderDocument(_ document: Document) -> NSAttributedString {
     return renderBlocks(
       document.blocks,
       state: .init(
-        font: style.font,
-        foregroundColor: style.foregroundColor,
-        paragraphSpacing: style.measurements.paragraphSpacing
+        font: environment.style.font,
+        foregroundColor: environment.style.foregroundColor,
+        paragraphSpacing: environment.style.measurements.paragraphSpacing
       )
     )
   }
@@ -101,8 +97,8 @@ extension AttributedStringRenderer {
 
     var state = state
     state.font = state.font.italic()
-    state.headIndent += style.measurements.headIndentStep
-    state.tailIndent += style.measurements.tailIndentStep
+    state.headIndent += environment.style.measurements.headIndentStep
+    state.tailIndent += environment.style.measurements.tailIndentStep
     state.tabStops.append(
       .init(textAlignment: .natural, location: state.headIndent)
     )
@@ -129,13 +125,14 @@ extension AttributedStringRenderer {
     let result = NSMutableAttributedString()
 
     var itemState = state
-    itemState.paragraphSpacing = bulletList.tight ? 0 : style.measurements.paragraphSpacing
-    itemState.headIndent += style.measurements.headIndentStep
+    itemState.paragraphSpacing =
+      bulletList.tight ? 0 : environment.style.measurements.paragraphSpacing
+    itemState.headIndent += environment.style.measurements.headIndentStep
     itemState.tabStops.append(
       contentsOf: [
         .init(
-          textAlignment: .trailing(baseWritingDirection),
-          location: itemState.headIndent - style.measurements.listMarkerSpacing
+          textAlignment: .trailing(environment.baseWritingDirection),
+          location: itemState.headIndent - environment.style.measurements.listMarkerSpacing
         ),
         .init(textAlignment: .natural, location: itemState.headIndent),
       ]
@@ -172,21 +169,24 @@ extension AttributedStringRenderer {
     // as the head indent step if higher than the style's head indent step.
     let highestNumber = orderedList.start + orderedList.items.count - 1
     let headIndentStep = max(
-      style.measurements.headIndentStep,
+      environment.style.measurements.headIndentStep,
       NSAttributedString(
         string: "\(highestNumber).",
-        attributes: [.font: state.font.monospacedDigit().resolve(sizeCategory: sizeCategory)]
-      ).em() + style.measurements.listMarkerSpacing
+        attributes: [
+          .font: state.font.monospacedDigit().resolve(sizeCategory: environment.sizeCategory)
+        ]
+      ).em() + environment.style.measurements.listMarkerSpacing
     )
 
     var itemState = state
-    itemState.paragraphSpacing = orderedList.tight ? 0 : style.measurements.paragraphSpacing
+    itemState.paragraphSpacing =
+      orderedList.tight ? 0 : environment.style.measurements.paragraphSpacing
     itemState.headIndent += headIndentStep
     itemState.tabStops.append(
       contentsOf: [
         .init(
-          textAlignment: .trailing(baseWritingDirection),
-          location: itemState.headIndent - style.measurements.listMarkerSpacing
+          textAlignment: .trailing(environment.baseWritingDirection),
+          location: itemState.headIndent - environment.style.measurements.listMarkerSpacing
         ),
         .init(textAlignment: .natural, location: itemState.headIndent),
       ]
@@ -258,8 +258,8 @@ extension AttributedStringRenderer {
     state: State
   ) -> NSAttributedString {
     var state = state
-    state.font = state.font.scale(style.measurements.codeFontScale).monospaced()
-    state.headIndent += style.measurements.headIndentStep
+    state.font = state.font.scale(environment.style.measurements.codeFontScale).monospaced()
+    state.headIndent += environment.style.measurements.headIndentStep
     state.tabStops.append(
       .init(textAlignment: .natural, location: state.headIndent)
     )
@@ -313,14 +313,14 @@ extension AttributedStringRenderer {
 
     var inlineState = state
     inlineState.font = inlineState.font.bold().scale(
-      style.measurements.headingScales[heading.level - 1]
+      environment.style.measurements.headingScales[heading.level - 1]
     )
 
     result.append(renderInlines(heading.text, state: inlineState))
 
     // The paragraph spacing is relative to the parent font
     var paragraphState = state
-    paragraphState.paragraphSpacing = style.measurements.headingSpacing
+    paragraphState.paragraphSpacing = environment.style.measurements.headingSpacing
 
     result.addAttribute(
       .paragraphStyle,
@@ -342,7 +342,7 @@ extension AttributedStringRenderer {
       .init(
         string: .nbsp,
         attributes: [
-          .font: state.font.resolve(sizeCategory: sizeCategory),
+          .font: state.font.resolve(sizeCategory: environment.sizeCategory),
           .strikethroughStyle: NSUnderlineStyle.single.rawValue,
           .strikethroughColor: PlatformColor.separator,
         ]
@@ -425,7 +425,7 @@ extension AttributedStringRenderer {
     NSAttributedString(
       string: text,
       attributes: [
-        .font: state.font.resolve(sizeCategory: sizeCategory),
+        .font: state.font.resolve(sizeCategory: environment.sizeCategory),
         .foregroundColor: PlatformColor(state.foregroundColor),
       ]
     )
@@ -441,7 +441,7 @@ extension AttributedStringRenderer {
 
   private func renderInlineCode(_ inlineCode: InlineCode, state: State) -> NSAttributedString {
     var state = state
-    state.font = state.font.scale(style.measurements.codeFontScale).monospaced()
+    state.font = state.font.scale(environment.style.measurements.codeFontScale).monospaced()
     return renderText(inlineCode.code, state: state)
   }
 
@@ -466,7 +466,7 @@ extension AttributedStringRenderer {
     let absoluteURL =
       link.url
       .map(\.relativeString)
-      .flatMap { URL(string: $0, relativeTo: baseURL) }
+      .flatMap { URL(string: $0, relativeTo: environment.baseURL) }
       .map(\.absoluteURL)
     if let url = absoluteURL {
       result.addAttribute(.link, value: url, range: NSRange(0..<result.length))
@@ -483,19 +483,20 @@ extension AttributedStringRenderer {
   private func renderImage(_ image: CommonMark.Image, state: State) -> NSAttributedString {
     image.url
       .map(\.relativeString)
-      .flatMap { URL(string: $0, relativeTo: baseURL) }
+      .flatMap { URL(string: $0, relativeTo: environment.baseURL) }
       .map(\.absoluteURL)
       .map {
         NSAttributedString(markdownImageURL: $0)
       } ?? NSAttributedString()
   }
 
   private func paragraphStyle(state: State) -> NSParagraphStyle {
-    let pointSize = state.font.resolve(sizeCategory: sizeCategory).pointSize
+    let pointSize = state.font.resolve(sizeCategory: environment.sizeCategory).pointSize
     let result = NSMutableParagraphStyle()
     result.setParagraphStyle(.default)
-    result.baseWritingDirection = baseWritingDirection
-    result.alignment = alignment
+    result.baseWritingDirection = environment.baseWritingDirection
+    result.alignment = environment.alignment
+    result.lineSpacing = environment.lineSpacing
     result.paragraphSpacing = round(pointSize * state.paragraphSpacing)
     result.headIndent = round(pointSize * state.headIndent)
     result.tailIndent = round(pointSize * state.tailIndent)