attributed-string-builder/Sources/AttributedStringBuilder/Attributes.swift at main · spee/attributed-string-builder · GitHub

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//
//  Attributes.swift
//
//
//  Created by Juul Spee on 08/07/2022.

import AppKit

/// Attributes for `NSAttributedString`, wrapped in a struct for convenience.
public struct Attributes {
    public init(family: String = "Helvetica", size: CGFloat = 14, bold: Bool = false, italic: Bool = false, textColor: NSColor = .textColor, backgroundColor: NSColor? = nil, kern: CGFloat = 0, firstlineHeadIndent: CGFloat = 0, headIndent: CGFloat = 0, tabStops: [NSTextTab] = (1..<10).map { NSTextTab(textAlignment: .left, location: CGFloat($0) * 2 * 16) }, alignment: NSTextAlignment = .left, lineHeightMultiple: CGFloat = 1.3, minimumLineHeight: CGFloat? = nil, maximumLineHeight: CGFloat? = nil, paragraphSpacing: CGFloat = 14, paragraphSpacingBefore: CGFloat = 0, link: URL? = nil, cursor: NSCursor? = nil) {
        self.family = family
        self.size = size
        self.bold = bold
        self.italic = italic
        self.textColor = textColor
        self.backgroundColor = backgroundColor
        self.kern = kern
        self.firstlineHeadIndent = firstlineHeadIndent
        self.headIndent = headIndent
        self.tabStops = tabStops
        self.alignment = alignment
        self.lineHeightMultiple = lineHeightMultiple
        self.minimumLineHeight = minimumLineHeight
        self.maximumLineHeight = maximumLineHeight
        self.paragraphSpacing = paragraphSpacing
        self.paragraphSpacingBefore = paragraphSpacingBefore
        self.link = link
        self.cursor = cursor
    }

    public var family: String
    public var size: CGFloat
    public var bold: Bool = false
    public var italic: Bool = false
    public var textColor: NSColor = .textColor
    public var backgroundColor: NSColor? = nil
    public var kern: CGFloat = 0
    public var firstlineHeadIndent: CGFloat = 0
    public var headIndent: CGFloat = 0
    public var tabStops: [NSTextTab] = (1..<10).map { NSTextTab(textAlignment: .left, location: CGFloat($0) * 2 * 16) }
    public var alignment: NSTextAlignment = .left
    public var lineHeightMultiple: CGFloat = 1.3
    public var minimumLineHeight: CGFloat? = nil
    public var maximumLineHeight: CGFloat? = nil
    public var paragraphSpacing: CGFloat = 0
    public var paragraphSpacingBefore: CGFloat = 0
    public var link: URL? = nil
    public var cursor: NSCursor? = nil
    public var customAttributes: [String: Any] = [:]
}

extension Attributes {
    public mutating func setIndent(_ value: CGFloat) {
        firstlineHeadIndent = value
        headIndent = value
    }

    fileprivate var font: NSFont {
        var fontDescriptor = NSFontDescriptor(name: family, size: size)

        var traits = NSFontDescriptor.SymbolicTraits()
        if bold { traits.formUnion(.bold) }
        if italic { traits.formUnion(.italic )}
        if !traits.isEmpty { fontDescriptor = fontDescriptor.withSymbolicTraits(traits) }
        let font = NSFont(descriptor: fontDescriptor, size: size)!
        return font
    }

    fileprivate var paragraphStyle: NSParagraphStyle {
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.firstLineHeadIndent = firstlineHeadIndent
        paragraphStyle.headIndent = headIndent
        paragraphStyle.tabStops = tabStops
        paragraphStyle.alignment = alignment
        paragraphStyle.lineHeightMultiple = lineHeightMultiple
        paragraphStyle.minimumLineHeight = minimumLineHeight ?? 0
        paragraphStyle.maximumLineHeight = maximumLineHeight ?? 0 // 0 is the default
        paragraphStyle.paragraphSpacing = paragraphSpacing
        paragraphStyle.paragraphSpacingBefore = paragraphSpacingBefore
        return paragraphStyle
    }

    /// Outputs a dictionary of the attributes that can be passed into an attributed string.
    public var atts: [NSAttributedString.Key:Any] {
        var result: [NSAttributedString.Key: Any] = [
            .font: font,
            .foregroundColor: textColor,
            .kern: kern,
            .paragraphStyle: paragraphStyle,
        ]
        if let bg = backgroundColor {
            result[.backgroundColor] = bg
        }
        if let url = link {
            result[.link] = url
        }
        if let cursor {
            result[.cursor] = cursor
        }
        for (key, value) in customAttributes {
            result[NSAttributedString.Key(key)] = value
        }
        return result
    }
}

extension NSAttributedString {
    public convenience init(string: String, attributes: Attributes) {
        self.init(string: string, attributes: attributes.atts)
    }
}