In implementing caret browsing mode in pdf.js, I didn't notice that selectstart isn't always triggered.
So this patch removes the use of selectstart and rely only on selectionchange.
In order to simplify the selection management, the selection code is moved in the AnnotationUIManager:
- it simplifies the code;
- it allows to have only one listener for selectionchange instead of having one by visible page
for selectstart.
I had to add a delay in the integration tests for highlighting (there's a comment with an explanation),
it isn't really nice, but it's the only way I found and in real life there always is a delay between
press and release.
When highlighting, the annotation editor layer is disabled to get pointer events
from the text layer, but the annotation layer must be then disabled either in
order to avoid bad interactions.
Given that we need to pass in a `PDFDataRangeTransport`-instance a number of the needed parameters can be obtained from it, rather than having to specify them manually.
When an highlight is self-intersecting, the outline was drawn inside.
In order to remove it, we use a svg mask to exclude the shape inside
when drawing the outlines.
That leads to change the outline 1px,white-2px,blue-1px,white to a
2px,white-2px,blue: the part of the stroke which is inside the shape
is removed because of the mask.
It isn't really a fix for the mentioned bug but it slightly improve things.
In reducing the memory use, the time spent in the GC is reduced either.
The algorithm to compute the bounding box is the same as before but it has just
been rewritten to be more efficient.
This manually ignores some cases where the resulting auto-formatting would not, as far as I'm concerned, constitute a readability improvement or where we'd just end up with more overall indentation.
Please see https://eslint.org/docs/latest/rules/arrow-body-style
For arrow functions that are both simple and short, we can avoid using explicit `return` to shorten them even further without hurting readability.
For the `gulp mozcentral` build-target this reduces the overall size of the output by just under 1 kilo-byte (which isn't a lot but still can't hurt).
In order to do that we must change the text layer opacity to 1 but
it has several implications:
- the selection color must have an alpha component,
- the background color of the span used for highlighted words
must have an alpha component either, but now the opacity is 1
we can use some backdrop-filters in HCM making the highlighted
words more visible.
- fix a regression caused by #17196: the css variable --hcm-highlight-filter
has to live under the #viewer element because in HCM it's overwritten
by js at this level, hence links annotations for example didn't
have the right colors when hovered.
The free highlighting is enabled when the mouse pointer isn't on some text.
Then we draw a shape with smoothed borders corresponding to the movement of
the mouse.
Printing/saving and changing the thickness will come later.
