Please note that the standalone `pdf.image_decoders.js` file will be including the complete `src/shared/util.js` file, despite only using parts of it.[1] This was done *purposely*, to not negatively impact the readability/maintainability of the core PDF.js code.
Furthermore, to ensure that the compatibility is the same in the regular PDF.js library *and* in the the standalone image decoders, `src/shared/compatibility.js` was included as well.
To (hopefully) prevent future complaints about the size of the built `pdf.image_decoders.js` file, a few existing async-related polyfills are being skipped (since all of the image decoders are completely synchronous).
Obviously this required adding a couple of pre-processor statements, but given that these are all limited to "compatibility" code, I think this might be OK!?
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[1] However, please note that previous commits moved `PageViewport` and `MessageHandler` out of `src/shared/util.js` which reduced its size.
Not only is the `Util.loadScript` helper function unused on the Worker side, even trying to use it there would throw an Error (since `document` isn't defined/available in Workers).
Hence this helper function is moved, and its code modernized slightly by having it return a Promise rather than needing a callback function.
Finally, to reduced code duplication, the "new" loadScript function is exported and used in the viewer.
The `MessageHandler` itself, and its assorted helper functions, are currently the single largest[1] piece of code in the `src/shared/util.js` file. By moving this code into its own file, `src/shared/util.js` thus becomes smaller and more manageable.
This function combines the logic of two separate methods into one.
The loop limit is also a good thing to have for the calls in
`src/core/annotation.js`.
Moreover, since this is important functionality, a set of unit tests and
documentation is added.
Unfortunately, as far as I can tell, we still need the ability to adjust certain API options depending on the browser environment in PDF.js version `2.0`. However, we should be able to separate this from the general compatibility code in the `src/shared/compatibility.js` file.
I don't understand why the previous way importing the polyfills didn't work, and I don't have time to try and figure it out, however this patch seems to fix things.
Fixes 9514.
Fixes 9516.
Unfortunately, as far as I can tell, we still need the ability to adjust certain viewer options depending on the browser environment in PDF.js version `2.0`. However, we should be able to separate this from the general compatibility code in the `src/shared/compatibility.js` file.
This rule is available from https://www.npmjs.com/package/eslint-plugin-mozilla, and is enforced in mozilla-central. Note that we have the necessary `Array`/`String` polyfills and that most cases have already been fixed, see PRs 9032 and 9434.
This rule is available from https://www.npmjs.com/package/eslint-plugin-mozilla, and is enforced in mozilla-central. Note that we have a polyfill for `ChildNode.remove()` and that most cases have already been fixed, see PRs 8056 and 8138.
Since `loadJpegStream` is only used at a *single* spot in the code-base, and given that it's very heavily tailored to the calling code (since it relies on the data structure of `PDFObjects`), this patch simply inlines the code in `src/display/api.js` instead.
Add comments with supported browser versions where missing.
Method:
- Use MDN compat tables if available.
- Otherwise test in Chrome (31+) otherwise.
(the Chrome Web Store does not update older versions of
Chrome, so probably nobody is interested in even older
versions, even though there is an existing comment for
Chrome<29 at `document.currentScript`).
These were removed in PR 9170, since they were unused in the browsers that we'll support in PDF.js version `2.0`.
However looking at the output of Travis, where a subset of the unit-tests are run using Node.js, there's warnings about `btoa` being undefined. This doesn't appear to cause any errors, which probably explains why we didn't notice this before (despite PR 9201).
It is quite confusing that the custom function is called `log2` while it
actually returns the ceiling value and handles zero and negative values
differently than the native function.
To resolve this, we add a comment that explains these differences and
make the function use the native `Math` functions internally instead of
using our own custom logic. To verify that the function does what we
expect, we add unit tests.
All browsers except for IE support `Math.log2` for quite a long time
already (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/log2).
For IE, we use the core-js polyfill.
According to the microbenchmark at https://jsperf.com/log2-pdfjs/1,
using the native functions should also be faster, in my testing almost
six times as fast.
We're currently disabling range requests and streaming for a number of configurations. A couple of those will no longer be supported (with PDF.js version 2.0), hence we ought to be able to clean up the compatibility code slightly.
This compatibility code is only relevant for browsers that will no longer be supported (with PDF.js version 2.0), hence we ought to be able to remove it.
Since we're already using core-js elsewhere in `compatibility.js`, we can reduce the amount of code we need to maintain ourselves.
https://github.com/zloirock/core-js#weakmap
