gristlabs_grist-core/app/client/ui/viewport.ts

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import {isIOS} from 'app/client/lib/browserInfo';
import {localStorageBoolObs} from 'app/client/lib/localStorageObs';
import {dom} from 'grainjs';
export const viewportEnabled = localStorageBoolObs('viewportEnabled', true);
export function toggleViewport() {
viewportEnabled.set(!viewportEnabled.get());
if (!viewportEnabled.get()) {
// Removing the meta tag doesn't cause mobile browsers to reload automatically.
location.reload();
}
}
export function addViewportTag() {
dom.update(document.head,
dom.maybe(viewportEnabled, () => {
// For the maximum-scale=1 advice, see https://stackoverflow.com/a/46254706/328565. On iOS,
// it prevents the auto-zoom when an input is focused, but does not prevent manual
// pinch-to-zoom. On Android, it's not needed, and would prevent manual zoom.
const viewportContent = "width=device-width,initial-scale=1.0" + (isIOS() ? ",maximum-scale=1" : "");
return dom('meta', {name: "viewport", content: viewportContent});
})
);
}