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Keys from specsForTextStyles

Alberto Martínez edited this page Aug 20, 2018 · 3 revisions

The result of the rnTextSize specsForTextStyles function is a collection whose keys depends on the OS.

Text Styles for Android

The key names and values are hard-coded in rnTextSize and follow the current Material Design Guidelines.

The fontFamily is defined with their 'sans-serif' equivalent, which determines the font weight implicitly.

The use of 'sans-serif' as fontFamily will render "Roboto" by default, but it will repect a different font on devices where the manufacturer (or the user) has changed it.

The units for width and letterSpacing are SPs, so that you can apply allowFontScaling at your convenience.

Key fontFamily fontSize letterSpacing*
h1 sans-serif-light 96 -1.5
h2 sans-serif-light 60 -0.5
h3 sans-serif 48 0
h4 sans-serif 34 0.25
h5 sans-serif 24 0
h6 sans-serif-medium 20 0.15
subtitle1 sans-serif 16 0.15
subtitle2 sans-serif-medium 14 0.1
body1 sans-serif 16 0.5
body2 sans-serif 14 0.25
button sans-serif-medium 14 0.75
caption sans-serif 12 0.4
overline sans-serif 10 1.5

* letterSpacing is included if running React Native v0.55 or later, but it only applies on devices with API 21 or later.

Note: The Material Design guide determines that both, 'button' and 'overline' text must be uppercase, but the textTransform property is not supported in RN for Android, so it is excluded.

Text Styles for iOS

The resulting info is obtained dynamically from the iOS UIKit merged with unscaled font size and letter spacing constants that follow the Human Interface Guidelines recommendations.

Each key has an UIFontTextStyle equivalent:

Key fontSize letterSpacing UIFontTextStyle constant
largeTitle 34 0.374 UIFontTextStyleLargeTitle // added in iOS 11
title1 28 0.364 UIFontTextStyleTitle1
title2 22 0.352 UIFontTextStyleTitle2
title3 20 0.38 UIFontTextStyleTitle3
headline 17 -0.408 UIFontTextStyleHeadline
body 17 -0.408 UIFontTextStyleBody
callout 16 -0.32 UIFontTextStyleCallout
subhead 15 -0.24 UIFontTextStyleSubheadline
footnote 13 -0.78 UIFontTextStyleFootnote
caption1 12 0.0 UIFontTextStyleCaption1
caption2 11 0.066 UIFontTextStyleCaption2
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