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Check if pageView.pdfPage exists in PDFViewer._ensurePdfPageLoaded, to avoid potentially calling PDFPageView.setPdfPage multiple times for the same page

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Since calling `PDFPageView.setPdfPage` will in turn call `PDFPageView.reset`, which cancels all rendering and completely resets the page, it's thus possible that we currently cause some unnecessary re-rendering during the initial loading phase of the viewer.

Depending on the order in which data arrives, it's possible (and in practice always seem to happen) that the `pdfPage` property of the *second* page has already been set during `PDFViewer.setDocument`, by the time that the request for the `pdfPage` is resolved in `PDFViewer._ensurePdfPageLoaded`.

Also, note how the `setPdfPage` call in `PDFViewer.setDocument` is already guarded by this kind of check.
This commit is contained in:
Jonas Jenwald 2017-04-16 13:10:56 +02:00
parent b0a4f6de8f
commit fce2cfddcf
1 changed files with 7 additions and 6 deletions
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13
web/pdf_viewer.js
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@ -843,12 +843,13 @@ var PDFViewer = (function pdfViewer() {
if (this._pagesRequests[pageNumber]) {
return this._pagesRequests[pageNumber];
}
var promise = this.pdfDocument.getPage(pageNumber).then(
function (pdfPage) {
pageView.setPdfPage(pdfPage);
var promise = this.pdfDocument.getPage(pageNumber).then((pdfPage) => {
if (!pageView.pdfPage) {
pageView.setPdfPage(pdfPage);
}
this._pagesRequests[pageNumber] = null;
return pdfPage;
}.bind(this));
});
this._pagesRequests[pageNumber] = promise;
return promise;
},
@ -859,9 +860,9 @@ var PDFViewer = (function pdfViewer() {
this._pages,
this.scroll.down);
if (pageView) {
this._ensurePdfPageLoaded(pageView).then(function () {
this._ensurePdfPageLoaded(pageView).then(() => {
this.renderingQueue.renderView(pageView);
}.bind(this));
});
return true;
}
return false;