The method signature was improved in PR 7440, which has now been present in a number of releases (starting with `v1.6.210`).
Hence we should be able to remove this now, and just print an error message if the old format is used.
Currently a number of these properties do not work correctly if set *before* calling `setDocument`; please refer to the discussion starting in https://github.com/mozilla/pdf.js/pull/8539#issuecomment-309706629.
Rather than trying to have *some* of these methods working, but not others, it seems much more consistent to simply always require that `setDocument` has been called.
This method is currently called from `PDFViewer._scrollUpdate` on *every* scroll event in the viewer.
However, I cannot see why this code is now necessary (assuming that it once was), since text-selection and searching still works *exactly* the same way with this patch as with the current `master`.
When `PDFPageView.updatePosition` is called, the page can be in either of these states:
1. The page hasn't been rendered, in which case the `textLayer` property doesn't exist yet.
2. The page is currently rendering, meaning that the `textLayer` property exists. Given that the `textContent` won't be fetched until the page has been successfully rendered, `TextLayerBuilder.render` will return immediately and effectively be a no-op (since there's nothing to render yet).
3. The has been been rendered, and the `textLayer` is currently rendering.
4. The page, and its `textLayer`, has been completely rendered. In this case, `TextLayerBuilder.render` will return immediately and effectively be a no-op.
Here, only the *third* case seem to require any further analysis:
When scrolling occurs while the `textLayer` is rendering, `TextLayerBuilder.render` will via a helper method call `TextLayerRenderTask.cancel` (in src/display/text_layer.js) to stop processing.
However, due to the run-to-completion nature of JavaScript, once `TextLayerRenderTask._render` has been invoked `appendText` will always run.[1]
So even though we cancel rendering of pending `textLayer`s during scrolling, via the repeated `TextLayerBuilder.render` calls from within the `PDFPageView.updatePosition` method, that does *not* prevent us from running the code inside of `TextLayerRenderTask._render` over and over for the *same* page; which all seems *very* inefficient to me.[2]
All this will thus have the effect of delaying the *actual* rendering of a `textLayer` ever so slightly while scrolling in the viewer. However, it does so at the expense of potentially hundreds of unnecessary `appendText` calls.[3]
Hence it seems to me that it's less resource intensive overall to simply let rendering of the `textLayer` complete, once it has started. Obviously, we still abort all rendering of a page, and its `textLayer`, when it's being destroyed (e.g. by being evicted from the page cache).
In case that there's any worry that the patch could affect e.g. highlighting of search results, please note that the existing code in `TextLayerBuilder.render` already calls `updateMatches` when the `TextLayerTask` resolves successfully.
*I'm sorry that this became quite long, but to try and summarize:*
`PDFPageView.updatePosition` doesn't actually do anything in *most* cases. In the one case where it matters, it seems that it's actually doing more harm than good; which is why I'm proposing that we just remove it.
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[1] Although we may be able to skip the `render` call, provided that it happens *after* a `timeout` (as is the case in the default viewer).
[2] With current work being done to support streaming of `TextContent`, we'd also need to add just as many duplicate API calls to `PDFPageView.updatePosition`.
[3] The number of duplicate `appendText` calls is directly proportional not only to the scroll speed, but also to the number of pages in the document.
Please see http://eslint.org/docs/rules/object-shorthand.
For the most part, these changes are of the search-and-replace kind, and the previously enabled `no-undef` rule should complement the tests in helping ensure that no stupid errors crept into to the patch.
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.
In various viewer files, there's a number of cases where we basically duplicate the functionality of `createPromiseCapability` manually.
As far as I can tell, a couple of these cases have existed for a very long time, and notable even before the `createPromiseCapability` utility function existed.
Also, since we can write ES6 code now, the patch also replaces a couple of `bind` usages with arrow functions in code that's touched in the patch.
Note that as discussed on IRC, this makes the viewer slightly slower to load *only* in `gulp server` mode, however the difference seem slight enough that I think it will be fine.
Determine the page rotation at the same place as where the page size is
determined. This allows us to implement custom print page rotation logic
in one place, in the future.
Using `else` after `return` is not necessary, and can often lead to unnecessarily cluttered code. By using the `no-else-return` rule in ESLint we can avoid this pattern, see http://eslint.org/docs/rules/no-else-return.
This patch implements the page label functionality in a similar way as Adobe Reader.
For documents with page labels, if a non-existent page label is entered we'll try to fallback to the page number instead.
The patch also includes a preference (`disablePageLabels`), to make it easy to opt-out of using page labels if the user/implementor so wishes.
The way that `get/set currentPageLabel` is implemented in `PDFViewer`, is as wrappers for the corresponding `get/set currentPageNumber` functions, since that seemed like the cleanest solution.
The page labels are purposely *only* added to the page controls in the viewer UI, and not stored in e.g. the `ViewHistory`. Since doing so would mean adding unnecessary code complexity, without any real added value, and would also mean delaying the inital loading of PDF documents.
Note that this patch will ignore page labels if they are identical to standard page numbering, since in this case displaying the page labels adds no value (but only UI noise). The reason for handling this case specially, is that in practice a surprising number of PDF files include "pointless" page labels.
1. Expanding divs to improve text selection. (Yury)
2. Adding enhanceTextSelection as an option.
3. Moving feature functionality from text_layer_builder.js to text_layer.js.
4. Added expandTextDivs method to only load expanded divs on first click, and only show on subsequent clicks
With the viewer code now being split into various components/files, having an obsolete comment in `PDFViewer` that references thumbnails despite there being no other mentions of them in the entire file seems strange.
*Note:* This comment is simply a left-over from older versions of PDF.js, where the *entire* default viewer code was placed in just one file (and where we unconditionally created thumbnails, regardless whether they were visible or not).
There are PDF generators which create destinations with e.g. too large top values, which cause the wrong page to be scrolled into view because the offset becomes negative.
By ignoring negative offsets, we can prevent this issue, and get a similar behaviour as in Adobe Reader.
However, since we're also using `PDFViewer_scrollPageIntoView` in more cases than just when links (in the document/outline) are clicked, the patch adds a way to allow the caller to opt-out of this behaviour.
In e.g. the following situations, I think that we still want to be able to allow negative offsets: when restoring a position from the `ViewHistory`, when the `viewBookmark` button is used to obtain a link to the current position, or when maintaining the current position on zooming.
Rather than adding another parameter to `PDFViewer_scrollPageIntoView`, I've changed the signature to take an parameter object instead. To maintain backwards compatibility, I've added fallback code enclosed in a `GENERIC` preprocessor tag.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=874482.
With PR 7502 we no longer dispatch an event when the `val` is out of bounds, so to better communicate why nothing happens this patch logs an error in that case (similar to the logging of errors when trying to set an invalid scale).
The way that the default viewer is currently implemented, means that e.g. keyboard short-cuts could trigger the new error. Hence this patch also adds the necessary validation code, both to `app.js` and `pdf_link_service.js` to prevent unnecessary errors.
This patch attempts to cleanup a couple of things:
- Remove the `previousPageNumber` paramater. Prior to PR 7289, when the events were dispatched even when the active page didn't change, it made sense to be able to detect that in an event listener. However, now that's no longer the case, and furthermore other similar events (e.g. `scalechanging`/`scalechange`) don't include information about the previous state.
- Don't dispatch the events when the value passed to `set currentPageNumber` is out of bounds. Given that the active page doesn't change in this case, again similar to PR 7289, I don't think that the events should actually be dispatched in this case.
- Ensure that the value passed to `set currentPageNumber` is actually an integer, to avoid any issues (note how e.g. `set currentScale` has similar validation code).
Given that these changes could possibly affect the PDF.js `mochitest` integration tests in mozilla-central, in particular https://dxr.mozilla.org/mozilla-central/source/browser/extensions/pdfjs/test/browser_pdfjs_navigation.js, I ran the tests locally with this patch applied to ensure that they still pass.
From the discussion in issue 7445, it seems that there may be cases where an API consumer would want to get the text content as is, without combined text items.
After PR 7289, we'll now reset the current page view in cases where I don't think we should. To avoid this, this patch ensures that we'll not modify the position when the page number is out-of-bounds.
**STR:**
1. Open http://mozilla.github.io/pdf.js/web/viewer.html#page=1&zoom=auto,-98,696
2. Enter an invalid number, e.g. `1000`, in the `pageNumber` input.
**ER:**
The current position in the document shouldn't change, since the page number wasn't valid.
**AR:**
The document resets to the top of the page `1`.
With the changes in PR 7289, we no longer dispatch a 'pagechanging' event on load. Since most PDF documents open on the first page, this means that the `previous` and `firstPage` buttons are no longer correctly disabled.
To avoid this, this patch moves the code that updates various UI toolbar state into one method, which is then called on document initialization and from the various existing event handling functions.
Currently for explicit destinations, compared to named destinations, we manually try to build a hash that often times is a quite poor representation of the *actual* destination. (Currently this only, kind of, works for `\XYZ` destinations.)
For PDF files using explicit destinations, this can make it difficult/impossible to obtain a link to a specific section of the document through the URL.
Note that in practice most PDF files, especially newer ones, use named destinations and these are thus unnaffected by this patch.
This patch also fixes an existing issue in `PDFLinkService_getDestinationHash`, where a named destination consisting of only a number would not be handled correctly.
With the added, and already existing, type checks in place for destinations, I really don't think that this patch exposes any "sensitive" internal destination code not already accessible through normal hash parameters.
*Please note:* Just trying to improve the algorithm that generates the hash is unfortunately not possible in general, since there are a number of cases where it will simply never work well.
- First of all, note that `getDestinationHash` currently relies on the `_pagesRefCache`, hence it's possible that the hash returned is empty during e.g. ranged/streamed loading of a PDF file.
- Second of all, the currently computed hash is actually dependent on the document rotation. With named destinations, the fetched internal destination array is rotational invariant (as it should be), but this will not hold in general for the hash. We can easily avoid this issue by using a stringified destination array.
- Third of all, note that according to the PDF specification[1], `GoToR` destinations may actually contain explicit destination arrays. Since we cannot really construct a hash in `annotation.js`, we currently have no good way to support those. Even though this case seems *very* rare in practice (I've not actually seen such a PDF file), it's in the specification, and this patch allows us to support that for "free".
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[1] http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf#G11.1951685
This patch makes the naming consistent with the `TextLayerBuilder`, and also the new `AnnotationLayer`, and should thus help reduce possible confusion when working with the code.
Please note that the files were renamed using `git mv`, in order to preserve blame.
