The scanned, black-and-white document at
https://bugzilla.mozilla.org/show_bug.cgi?id=835380 doesn't benefit from
the critical GRAYSCALE_1BPP optimization because the optimization is
skipped if `needsDecode` is set.
This change addresses that, and reduces both rendering time and memory
usage for that document by almost 10x.
As requested in #5178, this change debounces the scroll events.
The reason for doing so is that browsers can event-storm especially on
scroll, communicating hundreds of subpixel changes.
The main reason for this resulting in poor performance is that on each
scroll event `scrollTop` was queried, which forces layouting.
This change will use `requestAnimationFrame` to make sure the browser can
allocate enough time to other tasks. The delay is however quite small, thus
the reduction in executions is less noticeable. Modern browsers however utilize
`requestAnimationFrame` to smoothen out rendering.
setGStateForKey() is a closure that serves no particularly useful
purpose. This change inlines it at the single call site. This avoids 1.7
MiB of allocations (because closures are objects) for the MTA map
mentioned in https://bugzilla.mozilla.org/show_bug.cgi?id=835380#c17.
The data-font-name attribute of textLayer divs are only used by the Font
Inspector. This change ensures they are only present when the pdfBug
tools are enabled.
With the changes made in PR 5169 to enable quicker display of the File size, `setFileSize()` can now be called during file loading. This function parses *and* localizes the file size, where the l10n is a synchronous operation.
This patch:
* Re-factors `setFileSize()` to *only* update `rawFileSize`, and moves parsing and fetching of the l10n string to a separate method that isn't called until the Document Properties dialog is actually opened.
* Adds a couple of checks to make sure that `rawFileSize` is set to a positive number.
* Removes the `fileName` and `fileSize` properties. Since they are parsed every time the Document Properties dialog is opened, it doesn't seem necessary to cache them.
For the document in #2504, 11% of the ops are `setGState` with a
`gStateObj` that is an empty array, which is a no-op. This is possible
because we ignore various setGState keys (OP, OPM, BG, etc).
This change prevents these ops from being inserted into the operator
list.
This allows the JS engine to do a better job of allocating the right
number of elements for the array, avoiding some resizings. For the PDF
in #2504, this avoids 100s of MiBs of allocations in Firefox.
makeInlineImage() has a "are the next five chars ASCII?" check which is
run after an "EI" sequence has been found. This check involves the
creation of a new object because peekBytes() calls subarray().
Unfortunately, the check is currently run on whitespace chars even when
an "EI" sequence has not yet been found, i.e. when it's not needed. For
the PDF in #2618, there are over 820,000 such checks.
This change reworks the relevant loop so that the check is only done
once an "EI" sequence has been seen. This reduces the number of checks
to 157,000, and speeds up rendering by somewhere between 2% and 7% (the
measurements are noisy).
When the binary CMaps were added, some of the relevant unit tests were not changed. This patch updates them, so that we actually test the current implementation.
What's somewhat troubling here is that we currently have CMap unit tests that passes, *despite* not working as intended (the CMap files doesn't load).
