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Merge pull request #3507 from Snuffleupagus/PDFHistory-fix-multiple-identical-states

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[PDFHistory] Prevent the history from getting stuck in certain edge cases
This commit is contained in:
Brendan Dahl 2013-09-04 12:09:41 -07:00
commit 189d444ded
1 changed files with 18 additions and 1 deletions
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19
web/pdf_history.js
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@ -231,6 +231,22 @@ var PDFHistory = {
beforeUnload) {
if (!(this.currentBookmark && this.currentPage)) {
return null;
} else if (this.updatePreviousBookmark) {
this.updatePreviousBookmark = false;
}
if (this.uid > 0 && !(this.previousBookmark && this.previousPage)) {
// Prevent the history from getting stuck in the current state,
// effectively preventing the user from going back/forward in the history.
//
// This happens if the current position in the document didn't change when
// the history was previously updated. The reasons for this are either:
// 1. The current zoom value is such that the document does not need to,
// or cannot, be scrolled to display the destination.
// 2. The previous destination is broken, and doesn't actally point to a
// position within the document.
// (This is either due to a bad PDF generator, or the user making a
// mistake when entering a destination in the hash parameters.)
return null;
}
if ((!this.current.dest && !onlyCheckPage) || beforeUnload) {
if (this.previousBookmark === this.currentBookmark) {
@ -265,7 +281,8 @@ var PDFHistory = {
if (addPrevious && !overwrite) {
var previousParams = this._getPreviousParams();
if (previousParams) {
var replacePrevious = (this.current.hash !== this.previousHash);
var replacePrevious = (!this.current.dest &&
this.current.hash !== this.previousHash);
this._pushToHistory(previousParams, false, replacePrevious);
}
}