73 lines
2.8 KiB
TypeScript
73 lines
2.8 KiB
TypeScript
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/**
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* Pure helpers for controlled text inputs that must not fight CJK IME composition.
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*
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* Deferred parent updates (e.g. startTransition) against `value={external}` reset
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* the DOM mid-composition and break Windows IMEs (candidate dismiss / pinyin echo).
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*/
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export function shouldCommitImeControlledChange(input: {
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isComposingSession: boolean;
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nativeEventIsComposing?: boolean;
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/**
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* When true, the open (or just-ended) composition was discarded by an external
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* value change (e.g. navigation cleared the filter). Suppress commits so a
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* post-compositionend `onChange` cannot reassert the stale composed draft.
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*/
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compositionExternallySuperseded?: boolean;
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}): boolean {
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if (input.compositionExternallySuperseded) return false;
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return !input.isComposingSession && input.nativeEventIsComposing !== true;
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}
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export function shouldAdoptExternalImeControlledValue(input: {
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isComposingSession: boolean;
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draftValue: string;
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externalValue: string;
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/**
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* Committed external value captured at compositionstart. When provided during
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* an open composition, an external change relative to this baseline (e.g.
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* different-directory navigation setting filter to "") supersedes the draft
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* so compositionend cannot re-commit stale text over the navigation clear.
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*/
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valueAtComposeStart?: string;
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}): boolean {
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if (input.draftValue === input.externalValue) return false;
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if (!input.isComposingSession) return true;
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// Mid-composition: only adopt when parent moved away from the compose-start
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// baseline. Without a baseline, never fight the IME for self-driven drafts.
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if (input.valueAtComposeStart !== undefined) {
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return input.externalValue !== input.valueAtComposeStart;
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}
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return false;
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}
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/**
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* Resolve an input event when a composition may have been externally superseded
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* (navigation clear mid-IME). Browsers often re-fire the composed text via
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* `onChange` with `isComposing=false` immediately after `compositionend`; that
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* follow-up must not reassert the stale draft.
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*
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* - While still composing after supersede: keep ignoring event values (draft stays
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* on the external value) and keep the latch armed.
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* - Once composition has fully ended: ignore that one post-composition change and
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* clear the latch so subsequent ordinary typing commits normally.
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*/
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export function resolveSupersededImeInputEvent(input: {
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compositionExternallySuperseded: boolean;
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isComposingSession: boolean;
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nativeEventIsComposing?: boolean;
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}): {
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ignoreEventValue: boolean;
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clearSupersedeLatch: boolean;
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} {
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if (!input.compositionExternallySuperseded) {
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return { ignoreEventValue: false, clearSupersedeLatch: false };
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}
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const compositionFullyEnded =
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!input.isComposingSession && input.nativeEventIsComposing !== true;
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return {
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ignoreEventValue: true,
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clearSupersedeLatch: compositionFullyEnded,
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};
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}
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