mirror of
https://github.com/getpaseo/paseo.git
synced 2026-11-03 23:23:21 +00:00
Mohamed Boudra
0a549945b5
Shape rows in native Canvas and CoreText, then place clusters on xterm columns so fallback font advances cannot separate text from its cursor. Wait for measured dimensions before attachment and repaint overhanging ink with affected rows. Use Android platform ICU to avoid bundling approximately 14 MB of data; retain and document the Android 10 conjunct limitation.
68 lines
2.7 KiB
Swift
68 lines
2.7 KiB
Swift
import CoreText
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import UIKit
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private let measureText = "mmmmmmmmmm"
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/// The terminal font at one size: a CTFont per face (regular, bold, italic, bold italic) and the
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/// cell those faces are laid out on. Cells are whole device pixels so every column origin is
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/// exact. CoreText's cascade list covers characters the family lacks.
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final class TerminalFont {
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let family: String
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let size: CGFloat
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let displayScale: CGFloat
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private let faces: [CTFont]
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/// Cell size and baseline in points, each a whole number of device pixels.
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let cellWidth: CGFloat
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let cellHeight: CGFloat
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let baseline: CGFloat
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let underlineOffset: CGFloat
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let underlineThickness: CGFloat
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let strikeOffset: CGFloat
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let strikeThickness: CGFloat
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init(family: String, size: CGFloat, displayScale: CGFloat) {
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self.family = family
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self.size = size
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self.displayScale = displayScale
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let regular = TerminalFont.makeFont(family: family, size: size, traits: [])
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faces = [
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regular,
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TerminalFont.makeFont(family: family, size: size, traits: .traitBold),
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TerminalFont.makeFont(family: family, size: size, traits: .traitItalic),
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TerminalFont.makeFont(family: family, size: size, traits: [.traitBold, .traitItalic]),
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]
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let pixel = { (value: CGFloat) in max(1, (value * displayScale).rounded()) / displayScale }
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let line = CTLineCreateWithAttributedString(
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NSAttributedString(string: measureText, attributes: [.font: regular]))
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let width = CGFloat(CTLineGetTypographicBounds(line, nil, nil, nil))
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cellWidth = pixel(width / CGFloat(measureText.count))
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let ascent = CTFontGetAscent(regular)
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let descent = CTFontGetDescent(regular)
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let leading = CTFontGetLeading(regular)
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cellHeight = pixel(ascent + descent + leading)
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baseline = pixel(ascent)
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underlineOffset = -CTFontGetUnderlinePosition(regular)
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underlineThickness = max(1 / displayScale, CTFontGetUnderlineThickness(regular))
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strikeOffset = -CTFontGetXHeight(regular) / 2
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strikeThickness = underlineThickness
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}
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func font(flags: Int) -> CTFont { faces[TerminalFont.face(flags: flags)] }
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func sameAs(family: String, size: CGFloat, displayScale: CGFloat) -> Bool {
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self.family == family && self.size == size && self.displayScale == displayScale
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}
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static func face(flags: Int) -> Int {
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(flags & TerminalStyleFlags.bold != 0 ? 1 : 0) + (flags & TerminalStyleFlags.italic != 0 ? 2 : 0)
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}
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private static func makeFont(family: String, size: CGFloat, traits: UIFontDescriptor.SymbolicTraits) -> CTFont {
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let base = UIFontDescriptor(fontAttributes: [.family: family])
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let descriptor = traits.isEmpty ? base : (base.withSymbolicTraits(traits) ?? base)
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return UIFont(descriptor: descriptor, size: size) as CTFont
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}
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}
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