@mocanvas/editor · function
declare function resolveLineHeightPx(lineHeight: number | string | undefined, fontSizePx: number): numberA line height in page units, from whatever the theme or a shape gave.
Line height is the one text metric that is written two ways: as a unitless
multiplier (1.4, meaning "of the font size") and as an absolute length
("22px"). Both are legal CSS and both turn up in themes and in pasted
content, and measuring text against the wrong reading is off by a factor of
the font size — which is not a subtle bug, but is a silent one.
SEMANTICS-ASSUMED: a bare number, or a number-valued string with no unit, is
a multiplier; px is absolute; em and % are relative to the font size.
That is CSS's own rule for line-height, which is where every one of these
values came from.
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