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Slightly improve the BaseViewer.{firstPagePromise, onePageRendered, pagesPromise} functionality

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There's a couple of issues with this functionality:
 - The respective `PromiseCapability` instances are not being reset, in `BaseViewer._resetView`, when the document is closed which is inconsistent with all other state.
 - While the default viewer depends on these promises, and they thus ought to be considered part of e.g. the `PDFViewer` API-surface, they're not really defined in a particularily user-visible way (being that they're attached to the `BaseViewer` instance *inline* in `BaseViewer.setDocument`).
 - There's some internal `BaseViewer` state, e.g. `BaseViewer._pageViewsReady`, which is tracked manually and could instead be tracked indirectly via the relevant `PromiseCapability`, thus reducing the need to track state *twice* since that's always best to avoid.

*Please note:* In the existing implementation, these promises are not defined *until* the `BaseViewer.setDocument` method has been called.
While it would've been simple to lift that restriction in this patch, I'm purposely choosing *not* to do so since this ensures that any Promise handlers added inside of `BaseViewer.setDocument` are always invoked *before* any external ones (and keeping that behaviour seems generally reasonable).
This commit is contained in:
Jonas Jenwald 2020-03-07 13:11:51 +01:00
parent 7b07b88e71
commit 1fac29d184
2 changed files with 32 additions and 24 deletions
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4
web/app.js
View File

@ -1057,9 +1057,7 @@ const PDFViewerApplication = {
const pdfViewer = this.pdfViewer;
pdfViewer.setDocument(pdfDocument);
const firstPagePromise = pdfViewer.firstPagePromise;
const pagesPromise = pdfViewer.pagesPromise;
const onePageRendered = pdfViewer.onePageRendered;
const { firstPagePromise, onePageRendered, pagesPromise } = pdfViewer;
const pdfThumbnailViewer = this.pdfThumbnailViewer;
pdfThumbnailViewer.setDocument(pdfDocument);

52
web/base_viewer.js
View File

@ -198,13 +198,13 @@ class BaseViewer {
* @type {boolean} - True if all {PDFPageView} objects are initialized.
*/
get pageViewsReady() {
if (!this._pageViewsReady) {
if (!this._pagesCapability.settled) {
return false;
}
// Prevent printing errors when 'disableAutoFetch' is set, by ensuring
// that *all* pages have in fact been completely loaded.
return this._pages.every(function(pageView) {
return !!(pageView && pageView.pdfPage);
return pageView && pageView.pdfPage;
});
}
@ -376,6 +376,21 @@ class BaseViewer {
}
}
get firstPagePromise() {
return this.pdfDocument ? this._firstPageCapability.promise : null;
}
get onePageRendered() {
return this.pdfDocument ? this._onePageRenderedCapability.promise : null;
}
get pagesPromise() {
return this.pdfDocument ? this._pagesCapability.promise : null;
}
/**
* @private
*/
get _setDocumentViewerElement() {
// In most viewers, e.g. `PDFViewer`, this should return `this.viewer`.
throw new Error("Not implemented: _setDocumentViewerElement");
@ -399,24 +414,15 @@ class BaseViewer {
return;
}
const pagesCount = pdfDocument.numPages;
const firstPagePromise = pdfDocument.getPage(1);
const pagesCapability = createPromiseCapability();
this.pagesPromise = pagesCapability.promise;
pagesCapability.promise.then(() => {
this._pageViewsReady = true;
this._pagesCapability.promise.then(() => {
this.eventBus.dispatch("pagesloaded", {
source: this,
pagesCount,
});
});
const onePageRenderedCapability = createPromiseCapability();
this.onePageRendered = onePageRenderedCapability.promise;
const firstPagePromise = pdfDocument.getPage(1);
this.firstPagePromise = firstPagePromise;
this._onBeforeDraw = evt => {
const pageView = this._pages[evt.pageNumber - 1];
if (!pageView) {
@ -429,10 +435,10 @@ class BaseViewer {
this.eventBus._on("pagerender", this._onBeforeDraw);
this._onAfterDraw = evt => {
if (evt.cssTransform || onePageRenderedCapability.settled) {
if (evt.cssTransform || this._onePageRenderedCapability.settled) {
return;
}
onePageRenderedCapability.resolve();
this._onePageRenderedCapability.resolve();
this.eventBus._off("pagerendered", this._onAfterDraw);
this._onAfterDraw = null;
@ -443,6 +449,8 @@ class BaseViewer {
// viewport for all pages
firstPagePromise
.then(firstPdfPage => {
this._firstPageCapability.resolve(firstPdfPage);
const scale = this.currentScale;
const viewport = firstPdfPage.getViewport({ scale: scale * CSS_UNITS });
for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
@ -485,7 +493,7 @@ class BaseViewer {
// Fetch all the pages since the viewport is needed before printing
// starts to create the correct size canvas. Wait until one page is
// rendered so we don't tie up too many resources early on.
onePageRenderedCapability.promise.then(() => {
this._onePageRenderedCapability.promise.then(() => {
if (this.findController) {
this.findController.setDocument(pdfDocument); // Enable searching.
}
@ -497,13 +505,13 @@ class BaseViewer {
pagesCount > 7500
) {
// XXX: Printing is semi-broken with auto fetch disabled.
pagesCapability.resolve();
this._pagesCapability.resolve();
return;
}
let getPagesLeft = pagesCount - 1; // The first page was already loaded.
if (getPagesLeft <= 0) {
pagesCapability.resolve();
this._pagesCapability.resolve();
return;
}
for (let pageNum = 2; pageNum <= pagesCount; ++pageNum) {
@ -515,7 +523,7 @@ class BaseViewer {
}
this.linkService.cachePageRef(pageNum, pdfPage.ref);
if (--getPagesLeft === 0) {
pagesCapability.resolve();
this._pagesCapability.resolve();
}
},
reason => {
@ -524,7 +532,7 @@ class BaseViewer {
reason
);
if (--getPagesLeft === 0) {
pagesCapability.resolve();
this._pagesCapability.resolve();
}
}
);
@ -577,7 +585,9 @@ class BaseViewer {
this._location = null;
this._pagesRotation = 0;
this._pagesRequests = new WeakMap();
this._pageViewsReady = false;
this._firstPageCapability = createPromiseCapability();
this._onePageRenderedCapability = createPromiseCapability();
this._pagesCapability = createPromiseCapability();
this._scrollMode = ScrollMode.VERTICAL;
this._spreadMode = SpreadMode.NONE;