Before rendering block decorations, we read their heights by putting
them into a special div called `blockDecorationMeasurementsArea`.
Previously, this div was not explicitly sized, which was causing
decorations to wrap while being measured but not when actually rendering
them.
This commit fixes this inconsistency by explicitly styling the
measurement area so that it has the same width as the component scroll
width.
By the time that the animation frame is delivered, the requested
autoscroll
position could not exist anymore. This could cause the editor component
to measure a non-existent line and, as a result, throw an exception.
With this commit we will always ignore measurements for screen lines
that do not exist.
This means we may render more tiles than necessary when we have block
decorations, but it prevents changing the number of rendered tiles
during scrolling with certain combinations of line height and editor
height. If it ever becomes a problem we can get smarter about
subtracting the height of the visible block decorations from the editor
height, but for now this gives us more reliable performance for the
common case.
Previously, we were accidentally depending on the state of the display
layer when forcing it to update its index. This caused us to not index
enough content to cover the visibile area, which meant we weren't
querying enough lines to fill the screen in some situations.
This was causing problems in measurements because in that code path we
assume that text nodes are never empty. This commit also adds a test
verifying this invariant when a text decoration ending right after a
text tag is added.
This was leaving a measurement request in the map that was getting
picked up on the next frame. In some cases, the requested measurement
row was not present, causing an exception.
Some packages are interacting with this method assuming this behavior,
so this commit eliminates `screenPositionForPixelPositionSync` and
instead just performs the DOM update in `screenPositionForPixelPosition`
if it is needed.
Taking the initial measurement was setting the soft wrap column, which
was triggering a display layer reset, which was scheduling an update.
This update occurred at an unexpected time causing an exception.
I was hoping to strictly contain the layouts of highlights an lines
separately, since they are updated during different render phases.
Unfortunately, strict containment requires both divs to be positioned
absolutely. This in turn creates separate stacking contexts for lines
and highlights, which makes it impossible to render highlights in front
lines which themes sometimes need to do. For example,
atom-material-syntax pushes bracket matcher highlights to the front so
they are not obscured by the theme's solid black cursor line background.
/cc @as-cii. You should examine my work here and make sure I'm not
screwing something up with your line/block decoration update code.
