Develop

README.md

@@ -73,7 +73,40 @@ struct MyView: View {
 
 ### Fonts
 
-The view needs to be able to measure the current font's x-height to correctly size the characters inside of the rendered LaTeX SVG. To do that, the view must use the `UIFont`/`NSFont` classes and do its best to convert SwiftUI's `Font` structure into the correct `UIFont` instance. Currently, the view's functionality is limited to SwiftUI's static largeTitle, title, title1, headline, etc fonts.
+The view needs to be able to measure the current font's x-height to correctly size the characters inside of the rendered LaTeX SVG. To do that, the view must use the `UIFont`/`NSFont` classes and do its best to convert SwiftUI's `Font` structure into the correct `UIFont` instance. Currently, the view's functionality is limited to SwiftUI's static largeTitle, title, title1, headline, etc fonts, or by using `UIFont`/`NSFont` types directly.
+
+The `font` modifier has been overloaded so that you can give the `LaTeX` view `UIFont` and `NSFont` types directly. The following examples will render the size of the LaTeX correctly.
+
+```swift
+// SwiftUI perferred fonts
+LaTeX("Hello, $\\LaTeX$!")
+  .font(.title)
+
+LaTeX("Hello, $\\LaTeX$!")
+  .font(.caption)
+
+// Any UIFont/NSFont - note that they should be passed directly to the view
+LaTeX("Hello, $\\LaTeX$!")
+  .font(UIFont.systemFont(ofSize: 30))
+
+LaTeX("Hello, $\\LaTeX$!")
+  .font(UIFont(name: "Avenir", size: 25)!)
+```
+
+The following examples will _not_ render the size of the LaTeX correctly.
+
+```swift
+// SwiftUI Font type, but not a preferred font
+LaTeX("Hello, $\\LaTeX$!")
+  .font(.custom(name: "Avenir", size: 25))
+
+LaTeX("Hello, $\\LaTeX$!")
+  .font(.system(size: 25))
+
+// Wrapping UIFont/NSFont in a SwiftUI Font type
+LaTeX("Hello, $\\LaTeX$!")
+  .font(Font(UIFont.systemFont(ofSize: 30)))
+```
 
 ### Modifiers
 

Sources/LaTeXSwiftUI/Extensions/EnvironmentValues+Extensions.swift

@@ -74,10 +74,14 @@ private struct RenderingAnimationKey: EnvironmentKey {
   static let defaultValue: Animation? = .none
 }
 
-private struct IgnoreSringFormatting: EnvironmentKey {
+private struct IgnoreSringFormattingKey: EnvironmentKey {
   static let defaultValue: Bool = false
 }
 
+private struct PlatformFontKey: EnvironmentKey {
+  static let defaultValue: _Font? = nil
+}
+
 extension EnvironmentValues {
 
   /// The image rendering mode of this environment.
@@ -154,8 +158,14 @@ extension EnvironmentValues {
 
   /// Whether string formatting such as markdown should be ignored or rendered.
   var ignoreStringFormatting: Bool {
-    get { self[IgnoreSringFormatting.self] }
-    set { self[IgnoreSringFormatting.self] = newValue }
+    get { self[IgnoreSringFormattingKey.self] }
+    set { self[IgnoreSringFormattingKey.self] = newValue }
+  }
+
+  /// The specified UI/NSFont font to use, if any.
+  var platformFont: _Font? {
+    get { self[PlatformFontKey.self] }
+    set { self[PlatformFontKey.self] = newValue }
   }
 
 }

Sources/LaTeXSwiftUI/Extensions/View+Extensions.swift

@@ -170,4 +170,11 @@ public extension View {
     environment(\.ignoreStringFormatting, ignore)
   }
 
+  /// Sets the view's UI/NSFont font, if any.
+  /// - Parameter font: The UI/NSFont font to use.
+  /// - Returns: A view that uses the provided font.
+  internal func platformFont(_ font: _Font? = nil) -> some View {
+    environment(\.platformFont, font)
+  }
+
 }

Sources/LaTeXSwiftUI/LaTeX.swift

@@ -166,6 +166,9 @@ public struct LaTeX: View {
   /// The view's font.
   @Environment(\.font) private var font
 
+  /// The view's UI/NSFont font.
+  @Environment(\.platformFont) private var platformFont
+
   // MARK: Private properties
 
   /// The view's renderer.
@@ -235,6 +238,20 @@ extension LaTeX {
     style.makeBody(content: self)
   }
 
+#if os(iOS) || os(visionOS)
+  public func font(_ font: UIFont) -> some View {
+    self
+      .platformFont(font)
+      .font(Font(font))
+  }
+#else
+  public func font(_ font: NSFont) -> some View {
+    self
+      .platformFont(font)
+      .font(Font(font))
+  }
+#endif
+
 }
 
 // MARK: Private methods
@@ -255,7 +272,7 @@ extension LaTeX {
       parsingMode: parsingMode,
       processEscapes: processEscapes,
       errorMode: errorMode,
-      font: font ?? .body,
+      xHeight: (platformFont?.xHeight ?? font?.xHeight) ?? Font.body.xHeight,
       displayScale: displayScale)
   }
 
@@ -267,7 +284,7 @@ extension LaTeX {
       parsingMode: parsingMode,
       processEscapes: processEscapes,
       errorMode: errorMode,
-      font: font ?? .body,
+      xHeight: (platformFont?.xHeight ?? font?.xHeight) ?? Font.body.xHeight,
       displayScale: displayScale,
       renderingMode: imageRenderingMode)
   }
@@ -282,7 +299,7 @@ extension LaTeX {
       parsingMode: parsingMode,
       processEscapes: processEscapes,
       errorMode: errorMode,
-      font: font ?? .body,
+      xHeight: (platformFont?.xHeight ?? font?.xHeight) ?? Font.body.xHeight,
       displayScale: displayScale,
       renderingMode: imageRenderingMode)
   }

Sources/LaTeXSwiftUI/Models/Component.swift

@@ -192,7 +192,7 @@ extension Component {
   /// Converts the component to a `Text` view.
   ///
   /// - Parameters:
-  ///   - font: The font to use.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The view's display scale.
   ///   - renderingMode: The image rendering mode.
   ///   - errorMode: The error handling mode.
@@ -202,7 +202,7 @@ extension Component {
   ///     should be ignored or rendered.
   /// - Returns: A text view.
   func convertToText(
-    font: Font,
+    xHeight: CGFloat,
     displayScale: CGFloat,
     renderingMode: SwiftUI.Image.TemplateRenderingMode,
     errorMode: LaTeX.ErrorMode,
@@ -227,7 +227,6 @@ extension Component {
         }
       }
       else if let imageContainer {
-        let xHeight = _Font.preferredFont(from: font).xHeight
         let offset = svg.geometry.verticalAlignment.toPoints(xHeight)
         text = Text(imageContainer.image).baselineOffset(blockRenderingMode == .alwaysInline || !isInEquationBlock ? offset : 0)
       }

Sources/LaTeXSwiftUI/Models/ComponentBlock.swift

@@ -60,7 +60,7 @@ extension ComponentBlock {
   /// Converts a component block to a `Text` view.
   ///
   /// - Parameters:
-  ///   - font: The font to use.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The display scale.
   ///   - renderingMode: The rendering mode.
   ///   - errorMode: The error mode.
@@ -69,7 +69,7 @@ extension ComponentBlock {
   ///     should be ignored or rendered.
   /// - Returns: A `Text` view.
   @MainActor func toText(
-    font: Font?,
+    xHeight: CGFloat,
     displayScale: CGFloat,
     renderingMode: Image.TemplateRenderingMode,
     errorMode: LaTeX.ErrorMode,
@@ -78,7 +78,7 @@ extension ComponentBlock {
   ) -> Text {
     components.enumerated().map { i, component in
       return component.convertToText(
-        font: font ?? .body,
+        xHeight: xHeight,
         displayScale: displayScale,
         renderingMode: renderingMode,
         errorMode: errorMode,

Sources/LaTeXSwiftUI/Models/Renderer.swift

@@ -105,21 +105,21 @@ extension Renderer {
   ///   - parsingMode: The `parsingMode` environment variable.
   ///   - processEscapes: The `processEscapes` environment variable.
   ///   - errorMode: The `errorMode` environment variable.
-  ///   - font: The `font environment` variable.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The `displayScale` environment variable.
   func isCached(
     latex: String,
     unencodeHTML: Bool,
     parsingMode: LaTeX.ParsingMode,
     processEscapes: Bool,
     errorMode: LaTeX.ErrorMode,
-    font: Font,
+    xHeight: CGFloat,
     displayScale: CGFloat
   ) -> Bool {
     let texOptions = TeXInputProcessorOptions(processEscapes: processEscapes, errorMode: errorMode)
     return blocksExistInCache(
       parseBlocks(latex: latex, unencodeHTML: unencodeHTML, parsingMode: parsingMode),
-      font: font,
+      xHeight: xHeight,
       displayScale: displayScale,
       texOptions: texOptions)
   }
@@ -132,7 +132,7 @@ extension Renderer {
   ///   - parsingMode: The `parsingMode` environment variable.
   ///   - processEscapes: The `processEscapes` environment variable.
   ///   - errorMode: The `errorMode` environment variable.
-  ///   - font: The `font` environment variable.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The `displayScale` environment variable.
   ///   - renderingMode: The `renderingMode` environment variable.
   @MainActor func renderSync(
@@ -141,7 +141,7 @@ extension Renderer {
     parsingMode: LaTeX.ParsingMode,
     processEscapes: Bool,
     errorMode: LaTeX.ErrorMode,
-    font: Font,
+    xHeight: CGFloat,
     displayScale: CGFloat,
     renderingMode: SwiftUI.Image.TemplateRenderingMode
   ) -> [ComponentBlock] {
@@ -156,7 +156,7 @@ extension Renderer {
     let texOptions = TeXInputProcessorOptions(processEscapes: processEscapes, errorMode: errorMode)
     blocks = render(
       blocks: parseBlocks(latex: latex, unencodeHTML: unencodeHTML, parsingMode: parsingMode),
-      font: font,
+      xHeight: xHeight,
       displayScale: displayScale,
       renderingMode: renderingMode,
       texOptions: texOptions)
@@ -174,7 +174,7 @@ extension Renderer {
   ///   - parsingMode: The `parsingMode` environment variable.
   ///   - processEscapes: The `processEscapes` environment variable.
   ///   - errorMode: The `errorMode` environment variable.
-  ///   - font: The `font` environment variable.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The `displayScale` environment variable.
   ///   - renderingMode: The `renderingMode` environment variable.
   func render(
@@ -183,7 +183,7 @@ extension Renderer {
     parsingMode: LaTeX.ParsingMode,
     processEscapes: Bool,
     errorMode: LaTeX.ErrorMode,
-    font: Font,
+    xHeight: CGFloat,
     displayScale: CGFloat,
     renderingMode: SwiftUI.Image.TemplateRenderingMode
   ) async {
@@ -200,7 +200,7 @@ extension Renderer {
     let texOptions = TeXInputProcessorOptions(processEscapes: processEscapes, errorMode: errorMode)
     let renderedBlocks = render(
       blocks: parseBlocks(latex: latex, unencodeHTML: unencodeHTML, parsingMode: parsingMode),
-      font: font,
+      xHeight: xHeight,
       displayScale: displayScale,
       renderingMode: renderingMode,
       texOptions: texOptions)
@@ -249,14 +249,14 @@ extension Renderer {
   ///
   /// - Parameters:
   ///   - blocks: The component blocks.
-  ///   - font: The view's font.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The display scale to render at.
   ///   - renderingMode: The image rendering mode.
   ///   - texOptions: The MathJax Tex input processor options.
   /// - Returns: An array of rendered blocks.
   func render(
     blocks: [ComponentBlock],
-    font: Font,
+    xHeight: CGFloat,
     displayScale: CGFloat,
     renderingMode: SwiftUI.Image.TemplateRenderingMode,
     texOptions: TeXInputProcessorOptions
@@ -266,7 +266,7 @@ extension Renderer {
       do {
         let newComponents = try render(
           block.components,
-          xHeight: font.xHeight,
+          xHeight: xHeight,
           displayScale: displayScale,
           renderingMode: renderingMode,
           texOptions: texOptions)
@@ -288,7 +288,7 @@ extension Renderer {
   ///
   /// - Parameters:
   ///   - components: The components to render.
-  ///   - xHeight: The xHeight of the font to use.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The current display scale.
   ///   - renderingMode: The image rendering mode.
   ///   - texOptions: The MathJax TeX input processor options.
@@ -454,11 +454,11 @@ extension Renderer {
   ///
   /// - Parameters:
   ///   - blocks: The blocks.
-  ///   - font: The `font` environment variable.
+  ///   - xHeight: The font's x-height.
   ///   - displayScale: The `displayScale` environment variable.
   ///   - texOptions: The `texOptions` environment variable.
   /// - Returns: Whether the blocks are in the renderer's cache.
-  func blocksExistInCache(_ blocks: [ComponentBlock], font: Font, displayScale: CGFloat, texOptions: TeXInputProcessorOptions) -> Bool {
+  func blocksExistInCache(_ blocks: [ComponentBlock], xHeight: CGFloat, displayScale: CGFloat, texOptions: TeXInputProcessorOptions) -> Bool {
     for block in blocks {
       for component in block.components where component.type.isEquation {
         let dataCacheKey = Cache.SVGCacheKey(
@@ -473,7 +473,6 @@ extension Renderer {
           return false
         }
 
-        let xHeight = _Font.preferredFont(from: font).xHeight
         let imageCacheKey = Cache.ImageCacheKey(svg: svg, xHeight: xHeight)
         guard Cache.shared.imageCacheValue(for: imageCacheKey) != nil else {
           return false

Sources/LaTeXSwiftUI/Previews/LaTeX_Previews+Fonts.swift

@@ -0,0 +1,58 @@
+//
+//  LaTeX_Previews+Fonts.swift
+//  LaTeXSwiftUI
+//
+//  Copyright (c) 2025 Colin Campbell
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to
+//  deal in the Software without restriction, including without limitation the
+//  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+//  sell copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+//  IN THE SOFTWARE.
+//
+
+import SwiftUI
+
+#if os(iOS)
+import UIKit
+typealias PlatformFont = UIFont
+#else
+import Cocoa
+typealias PlatformFont = NSFont
+#endif
+
+struct LaTeX_Previews_Fonts: PreviewProvider {
+
+  static var previews: some View {
+    VStack {
+      LaTeX("Hello, $\\LaTeX$!")
+        .font(.system(size: 25))
+
+      LaTeX("Hello, $\\LaTeX$!")
+        .font(PlatformFont.preferredFont(forTextStyle: .title1))
+
+      LaTeX("Hello, $\\LaTeX$!")
+        .font(PlatformFont.systemFont(ofSize: 36))
+
+      LaTeX("Hello, $\\LaTeX$!")
+        .font(PlatformFont.boldSystemFont(ofSize: 25))
+
+      LaTeX("Hello, $\\LaTeX$!")
+        .font(PlatformFont(name: "Avenir", size: 25)!)
+    }
+    .previewDisplayName("Fonts")
+  }
+
+}