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Merge pull request #8885 from Snuffleupagus/PDFHistory-followup

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Address a couple of edge-cases in the new `PDFHistory` implementation (PR 8775 follow-up)
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Tim van der Meij 2017-09-08 23:10:45 +02:00 committed by GitHub
commit c8b5ba277a
1 changed files with 19 additions and 29 deletions
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web/pdf_history.js
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@ -21,7 +21,7 @@ const HASH_CHANGE_TIMEOUT = 1000; // milliseconds
// Heuristic value used when adding the current position to the browser history.
const POSITION_UPDATED_THRESHOLD = 50;
// Heuristic value used when adding a temporary position to the browser history.
const UPDATE_VIEWAREA_TIMEOUT = 2000; // milliseconds
const UPDATE_VIEWAREA_TIMEOUT = 1000; // milliseconds
/**
* @typedef {Object} PDFHistoryOptions
@ -189,6 +189,17 @@ class PDFHistory {
hash,
page: pageNumber,
}, forceReplace);
if (!this._popStateInProgress) {
// Prevent the browser history from updating while the new destination is
// being scrolled into view, to avoid potentially inconsistent state.
this._popStateInProgress = true;
// We defer the resetting of `this._popStateInProgress`, to account for
// e.g. zooming occuring when the new destination is being navigated to.
Promise.resolve().then(() => {
this._popStateInProgress = false;
});
}
}
/**
@ -358,6 +369,13 @@ class PDFHistory {
* @private
*/
_updateInternalState(destination, uid, removeTemporary = false) {
if (this._updateViewareaTimeout) {
// When updating `this._destination`, make sure that we always wait for
// the next 'updateviewarea' event before (potentially) attempting to
// push the current position to the browser history.
clearTimeout(this._updateViewareaTimeout);
this._updateViewareaTimeout = null;
}
if (removeTemporary && destination && destination.temporary) {
// When the `destination` comes from the browser history,
// we no longer treat it as a *temporary* position.
@ -475,34 +493,6 @@ class PDFHistory {
});
}
// This case corresponds to navigation backwards in the browser history.
if (state.uid < this._currentUid && this._position && this._destination) {
let shouldGoBack = false;
if (this._destination.temporary) {
// If the `this._destination` contains a *temporary* position, always
// push the `this._position` to the browser history before moving back.
this._pushOrReplaceState(this._position);
shouldGoBack = true;
} else if (this._destination.page &&
this._destination.page !== this._position.first &&
this._destination.page !== this._position.page) {
// If the `page` of the `this._destination` is no longer visible,
// push the `this._position` to the browser history before moving back.
this._pushOrReplaceState(this._destination);
this._pushOrReplaceState(this._position);
shouldGoBack = true;
}
if (shouldGoBack) {
// After `window.history.back()`, we must not enter this block on the
// resulting 'popstate' event, since that may cause an infinite loop.
this._currentUid = state.uid;
window.history.back();
return;
}
}
// Navigate to the new destination.
let destination = state.destination;
this._updateInternalState(destination, state.uid,