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

53 lines
1.4 KiB
TypeScript

/**
* 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))
}
// Chromium on Windows can drop webContents zoom when a BrowserWindow is minimized
// and restored. Re-apply the persisted level on these lifecycle transitions.
export const ZOOM_REASSERT_WINDOW_EVENTS = ['show', 'restore']
export function installZoomReassertOnWindowEvents(win, reassert) {
if (!win?.on) {
return
}
for (const event of ZOOM_REASSERT_WINDOW_EVENTS) {
win.on(event, () => {
if (win.isDestroyed?.()) {
return
}
reassert()
})
}
}