The minimum required version is Chrome 103 because wildcard support for
web_accessible_resources[].extension_id was introduced in 103, in
c9caeb1a08
A way to broaden compatibility is to drop that key. By doing so, the
minimum required Chrome version is then 96, because of the
chrome.storage.session API (and declarativeNetRequestWithHostAccess).
Since gulpfile.js already defines "Chrome >= 98" and there is no real
point in expanding support to older versions, I'm just setting the
minimum version to 103.
- Replace DOM-based pdfHandler.html (background page) with background.js
(extension service worker).
- Adjust logic of background scripts to account for the fact that the
scripts can execute repeatedly during a browser session. Primarily,
register relevant extension event handlers at the top level and use
in-memory storage.session API to keep track of initialization state.
- Extension URL router: replace blocking webRequest with the service
worker-specific "fetch" event.
- PDF detection: replace blocking webRequest with declarativeNetRequest.
This requires Chrome 128+. The next commit will add a fallback for
earlier Chrome versions.
In MV3, the background script is a service worker. localStorage is not
supported in service workers. Switch to storage.local instead.
Data migration is not implemented because it is not needed due to the
privacy-friendly design of the telemetry: In practice the data is reset
about every 4 weeks, when the major version of Chrome is updated.
restoretab.js was added in https://github.com/mozilla/pdf.js/pull/6233
with the purpose of restoring lost tabs when Chrome closes all extension
tabs when it reloads the extension. This forced reload can happen when
the user toggles the "Allow access to file URLs" option.
This logic does not work any more, and since the use of localStorage is
a blocker in migrating to MV3, this patch just drops the logic.
MV3 does not support chrome_style in options_ui. Remove it and replace
it with the minimal amount of styles that still has some spacing around
the individual settings for readability.
webRequestBlocking is unavailable in MV3. Non-blocking webRequest can
still be used to detect the Referer, but we have to use
declarativeNetRequest to change the Referer header as needed.
*Please note:* As a general rule we probably don't need to fix things affecting *custom* implementations of the default viewer, but in this case a "targeted" fix seem possible that shouldn't (famous last words) break anything else.
Ensure that the `.visibleMediumView` class, which is used when the viewer becomes narrow, cannot override the `display`-value for DOM elements that are being *explicitly* hidden either through the associated attribute or class.
The idea is to insert a span in the text layer with an aria-role set to img
and use the bounding box provided by the attribute field in the tag dict in
order to have non-null dimensions for the image to make it "visible".
In hindsight it occurred to me that there's a couple of smaller issues with this method after it's made asynchronous (in PR 18658).
- If the `render`-method is invoked back-to-back the existing caching doesn't guarantee that re-parsing won't occur, which we can address by introducing a new (private) promise.
- If there's any errors fetching and/or parsing the structTree-data, we'd attempt to parse it again on re-rendering despite that being pointless.
It has been tested with Voice Over (mac) and with NVDA (windows).
When an added stamp annotation is focused, the screen reader will announce
that it's a figure containing a graphic with the added alt-text.
