Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Updating size-adjust calculation #41406

Merged
merged 15 commits into from
Oct 20, 2022
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 2 additions & 1 deletion packages/font/src/local/loader.ts
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ import fontFromBuffer from '@next/font/dist/fontkit'
import type { AdjustFontFallback, FontLoader } from 'next/font'

import { promisify } from 'util'
import { validateData } from './utils'
import { calcAzWidth, validateData } from './utils'

const fetchFonts: FontLoader = async ({
functionName,
Expand Down Expand Up @@ -58,6 +58,7 @@ const fetchFonts: FontLoader = async ({
lineGap: fontMetadata.lineGap,
unitsPerEm: fontMetadata.unitsPerEm,
xAvgCharWidth: (fontMetadata as any)['OS/2']?.xAvgCharWidth,
azAvgWidth: calcAzWidth(fontMetadata),
})
adjustFontFallbackMetrics = {
fallbackFont,
Expand Down
11 changes: 11 additions & 0 deletions packages/font/src/local/utils.ts
Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
import type { Font } from 'fontkit'

const allowedDisplayValues = ['auto', 'block', 'swap', 'fallback', 'optional']

const formatValues = (values: string[]) =>
Expand Down Expand Up @@ -91,3 +93,12 @@ export function validateData(functionName: string, data: any): FontOptions {
declarations,
}
}

// Calculating the a-z average width
export function calcAzWidth(font: Font) {
const widths = font
.glyphsForString('abcdefghijklmnopqrstuvwxyz')
Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should we include space (" ") in the width?

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sounds good to me!

.map((glyph) => glyph.advanceWidth)
const totalWidth = widths.reduce((sum, width) => sum + width, 0)
return totalWidth / widths.length
}
8 changes: 4 additions & 4 deletions packages/next/server/font-utils.ts
Original file line number Diff line number Diff line change
Expand Up @@ -119,14 +119,14 @@ export function calculateOverrideValues(fontMetrics: any) {
}

export function calculateSizeAdjustValues(fontMetrics: any) {
let { category, ascent, descent, lineGap, unitsPerEm, xAvgCharWidth } =
let { category, ascent, descent, lineGap, unitsPerEm, azAvgWidth } =
fontMetrics
const fallbackFont =
category === 'serif' ? DEFAULT_SERIF_FONT : DEFAULT_SANS_SERIF_FONT

let sizeAdjust = xAvgCharWidth
? xAvgCharWidth / fallbackFont.xAvgCharWidth
: 1
const mainFontAvgWidth = azAvgWidth / unitsPerEm
const fallbackFontAvgWidth = fallbackFont.azAvgWidth / fallbackFont.unitsPerEm
let sizeAdjust = azAvgWidth ? mainFontAvgWidth / fallbackFontAvgWidth : 1

ascent = formatOverrideValue(ascent / (unitsPerEm * sizeAdjust))
descent = formatOverrideValue(descent / (unitsPerEm * sizeAdjust))
Expand Down
Loading