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fix: correcting Assistant metrics (#7758)

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* Changed Assistant metrics to the corrrect ones from OS/2 table

* Adding more information about font metrics

* Adding branded types to avoid future mistakes
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Marcel Mraz 2024-03-07 15:54:36 +00:00 • committed by GitHub
parent 68b1fdb20e
commit 480572f893
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2 changed files with 34 additions and 22 deletions
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54
packages/excalidraw/element/textElement.ts
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@ -31,7 +31,7 @@ import { getElementAbsoluteCoords } from ".";
import { getSelectedElements } from "../scene";
import { isHittingElementNotConsideringBoundingBox } from "./collision";
import { ExtractSetType } from "../utility-types";
import { ExtractSetType, MakeBrand } from "../utility-types";
import {
resetOriginalContainerCache,
updateOriginalContainerCache,
@ -928,38 +928,50 @@ const DEFAULT_LINE_HEIGHT = {
[FONT_FAMILY.Cascadia]: 1.2 as ExcalidrawTextElement["lineHeight"],
};
type FontMetrics = {
unitsPerEm: number; // head.unitsPerEm
ascender: number; // sTypoAscender
descender: number; // sTypoDescender
};
/** OS/2 sTypoAscender, https://learn.microsoft.com/en-us/typography/opentype/spec/os2#stypoascender */
type sTypoAscender = number & MakeBrand<"sTypoAscender">;
/** OS/2 sTypoDescender, https://learn.microsoft.com/en-us/typography/opentype/spec/os2#stypodescender */
type sTypoDescender = number & MakeBrand<"sTypoDescender">;
/** head.unitsPerEm, usually either 1000 or 2048 */
type unitsPerEm = number & MakeBrand<"unitsPerEm">;
/**
* Hardcoded metrics for default fonts, read by https://opentype.js.org/font-inspector.html.
* For custom fonts, read these metrics on load and extend this object.
* For custom fonts, read these metrics from OS/2 table and extend this object.
*
* WARN: opentype does NOT open WOFF2 correctly, make sure to convert WOFF2 to TTF first.
*/
const FONT_METRICS = {
export const FONT_METRICS: Record<
number,
{
unitsPerEm: number;
ascender: sTypoAscender;
descender: sTypoDescender;
}
> = {
[FONT_FAMILY.Virgil]: {
unitsPerEm: 1000,
ascender: 886,
descender: -374,
unitsPerEm: 1000 as unitsPerEm,
ascender: 886 as sTypoAscender,
descender: -374 as sTypoDescender,
},
[FONT_FAMILY.Helvetica]: {
unitsPerEm: 2048,
ascender: 1577,
descender: -471,
unitsPerEm: 2048 as unitsPerEm,
ascender: 1577 as sTypoAscender,
descender: -471 as sTypoDescender,
},
[FONT_FAMILY.Cascadia]: {
unitsPerEm: 2048,
ascender: 1977,
descender: -480,
unitsPerEm: 2048 as unitsPerEm,
ascender: 1977 as sTypoAscender,
descender: -480 as sTypoDescender,
},
[FONT_FAMILY.Assistant]: {
unitsPerEm: 1000,
ascender: 1050,
descender: -500,
unitsPerEm: 1000 as unitsPerEm,
ascender: 1021 as sTypoAscender,
descender: -287 as sTypoDescender,
},
} as Record<number, FontMetrics>;
};
export const getDefaultLineHeight = (fontFamily: FontFamilyValues) => {
if (fontFamily in DEFAULT_LINE_HEIGHT) {