hermes-agent/apps/desktop/electron/zoom.ts

/**
 * Pure helpers for window zoom. The main process owns webContents.setZoomLevel,
 * so the menu items, the Ctrl/Cmd shortcuts, and the settings UI all funnel
 * through this one clamped scale. Percent is the user-facing unit (100 = the
 * default size); Chromium's internal unit is the zoom level, where
 * factor = 1.2 ^ level.
 */

export const ZOOM_STORAGE_KEY = 'hermes:desktop:zoomLevel'

const ZOOM_FACTOR_BASE = 1.2
const MIN_ZOOM_LEVEL = -9
const MAX_ZOOM_LEVEL = 9

export function clampZoomLevel(value) {
  if (!Number.isFinite(value)) {return 0}

  return Math.min(Math.max(value, MIN_ZOOM_LEVEL), MAX_ZOOM_LEVEL)
}

export function zoomLevelToPercent(level) {
  return Math.round(Math.pow(ZOOM_FACTOR_BASE, clampZoomLevel(level)) * 100)
}

export function percentToZoomLevel(percent) {
  if (!Number.isFinite(percent) || percent <= 0) {return 0}

  return clampZoomLevel(Math.log(percent / 100) / Math.log(ZOOM_FACTOR_BASE))
}