- Improve chunking in order to fix some bugs where the spaces aren't here:
* track the last position where a glyph has been drawn;
* when a new glyph (first glyph in a chunk) is added then compare its position with the last saved one and add a space or break:
- there are multiple ways to move the glyphs and to avoid to have to deal with all the different possibilities it's a way easier to just compare positions;
- and so there is now one function (i.e. "compareWithLastPosition") where all the job is done.
- Add some breaks in order to get lines;
- Remove the multiple whites spaces:
* some spaces were filled with several whites spaces and so it makes harder to find some sequences of words using the search tool;
* other pdf readers replace spaces by one white space.
Update src/core/evaluator.js
Co-authored-by: Jonas Jenwald <jonas.jenwald@gmail.com>
Co-authored-by: Jonas Jenwald <jonas.jenwald@gmail.com>
Given that both the textLayer rendering *and* the structTree parsing is asynchronous, it's possible that we'll attempt to insert the structTree in a removed page. While there's thankfully no outright breakage caused by this, it will nonetheless lead to errors being printed in the console and we should obviously avoid this.
To reproduce this bug (without the patch), open http://localhost:8888/web/viewer.html?file=/test/pdfs/pdf.pdf#disableStream=true&disableAutoFetch=true and scroll *very quickly* through the document and notice the following error being (intermittently) printed in the console:
```
Uncaught (in promise) TypeError: can't access property "appendChild", this.canvas is undefined
```
Looking at the `ChunkedStream` implementation, it's basically a "regular" `Stream` but with added functionality in order to deal with fetching/loading of missing data.
Hence, by letting `ChunkedStream` extend `Stream`, we can remove some duplicate methods from the `ChunkedStream` class.
For all of the other `DecodeStream`s we're not passing in a `Dict`-instance manually, but instead get it from the `stream`-parameter. Hence there's no particularly good reason, as far as I can tell, to not do the same thing in `Jbig2Stream`/`JpegStream`/`JpxStream` as well.
The way that `getBaseStreams` is currently handled has bothered me from time to time, especially how we're checking if the method exists before calling it.
By adding a dummy `BaseStream.getBaseStreams` method, and having the call-sites simply check the return value, we can improve some of the relevant code.
Note in particular how the `ObjectLoader._walk` method didn't actually check that the data in question is a Stream instance, and instead only checked the `currentNode` (which could be anything) for the existence of a `getBaseStreams` property.
By having an abstract base-class, it becomes a lot clearer exactly which methods/getters are expected to exist on all Stream instances.
Furthermore, since a number of the methods are *identical* for all Stream implementations, this reduces unnecessary code duplication in the `Stream`, `DecodeStream`, and `ChunkedStream` classes.
For e.g. `gulp mozcentral`, the *built* `pdf.worker.js` files decreases from `1 619 329` to `1 616 115` bytes with this patch-series.
Given that we're using modules, meaning that only explicitly `export`ed things are visible to the outside, it's no longer necessary to wrap all of the code in a closure.
This gets rid of *a lot* of boilerplate that stems from our old way of simulating classes, and it actually reduces the filesize noticeably.
For e.g. `gulp mozcentral`, the *built* `pdf.js` files decreases from `318 404` to `314 722` bytes (~1 percent) with this patch.
This is done automatically with `gulp lint --fix` and the following
manual changes:
```diff
diff --git a/src/core/image.js b/src/core/image.js
index 35c06b8ab..e718b9937 100644
--- a/src/core/image.js
+++ b/src/core/image.js
@@ -97,7 +97,7 @@ class PDFImage {
if (isName(filter)) {
switch (filter.name) {
case "JPXDecode":
- var jpxImage = new JpxImage();
+ const jpxImage = new JpxImage();
jpxImage.parseImageProperties(image.stream);
image.stream.reset();
```
