62 lines
1.9 KiB
Swift
62 lines
1.9 KiB
Swift
import ExpoModulesCore
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/**
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A registry of font family aliases mapped to their real font family names.
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*/
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private var fontFamilyAliases = [String: String]()
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/**
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A flag that is set to `true` when the ``UIFont.fontNames(forFamilyName:)`` is already swizzled.
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*/
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private var hasSwizzled = false
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/**
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Manages the font family aliases and swizzles the `UIFont` class.
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*/
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internal struct FontFamilyAliasManager {
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/**
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Whether the given alias has already been set.
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*/
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internal static func hasAlias(_ familyNameAlias: String) -> Bool {
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return fontFamilyAliases[familyNameAlias] != nil
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}
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/**
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Sets the alias for the given family name.
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If the alias has already been set, its family name will be overriden.
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*/
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internal static func setAlias(_ familyNameAlias: String, forFont font: String) {
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maybeSwizzleUIFont()
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fontFamilyAliases[familyNameAlias] = font
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}
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/**
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Returns the family name for the given alias or `nil` when it's not set yet.
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*/
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internal static func familyName(forAlias familyNameAlias: String) -> String? {
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return fontFamilyAliases[familyNameAlias]
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}
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}
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/**
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Swizzles ``UIFont.fontNames(forFamilyName:)`` to support font family aliases.
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This is necessary because the user provides a custom family name that is then used in stylesheets,
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however the font usually has a different name encoded in the binary, thus the system may use a different name.
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*/
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private func maybeSwizzleUIFont() {
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if hasSwizzled {
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return
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}
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#if !os(macOS)
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let originalFontNamesMethod = class_getClassMethod(UIFont.self, #selector(UIFont.fontNames(forFamilyName:)))
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let newFontNamesMethod = class_getClassMethod(UIFont.self, #selector(UIFont._expo_fontNames(forFamilyName:)))
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if let originalFontNamesMethod, let newFontNamesMethod {
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method_exchangeImplementations(originalFontNamesMethod, newFontNamesMethod)
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} else {
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log.error("expo-font is unable to swizzle `UIFont.fontNames(forFamilyName:)`")
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}
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#endif
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hasSwizzled = true
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}
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