Alt screen applications normally reflow/readjust themselves on a
window resize.
When we do it too, the result is graphical glitches/flashes since our
re-flowed text is rendered in one frame, and the application re-flowed
text soon thereafter.
We can’t avoid rendering some kind of re-flowed frame, since we don’t
know when, or even if, the application will update itself. To avoid
glitches, we need to render, as closely as possible, what the
application itself will render shortly.
This is actually pretty simple; we just need to copy the visible
content over from the old grid to the new grid. We don’t bother with
text re-flow, but simply truncate long lines.
To simplify things, we simply cancel any active selection (since often
times, it will be corrupted anyway when the application redraws
itself).
Since we’re not reflowing text, there’s no need to translate e.g. the
cursor position - we just keep the current position (but bounded to
the new dimensions).
Fun thing: ‘less’ gets corrupted if we don’t leave the cursor at
the (new) bottom row. To handle this, we check if the cursor (before
resize) is at the bottom row, and if so, we move it to the new bottom
row.
Closes#221
* match search buffer against scrollback content
* adjust view to ensure matched content is visible
* create selection on a successful match
* finalize selection when user presses enter (to "commit" the search)
* ctrl+r searches for the next match. Needs more work though.
With this assumption, we can replace 'a % b' with 'a & (b - 1)'. In
terms of instructions, this means a fast 'and' instead of a slow
'div'.
Further optimize scrolling by:
* not double-initializing empty rows. Previously, grid_row_alloc()
called calloc(), which was then followed by a memset() when
scrolling. This is of course unnecessary.
* Don't loop the entire set of visible rows (this was done to ensure
all visible rows had been allocated, and to prefetch the cell
contents).
This isn't necessary; only newly pulled in rows can be NULL. For
now, don't prefetch at all.
The row array may now contain NULL pointers. This means the
corresponding row hasn't yet been allocated and initialized.
On a resize, we explicitly allocate the visible rows.
Uninitialized rows are then allocated the first time they are
referenced.
Can scroll up and down, and stops when the beginning/end of history is
reached.
However, it probably breaks when the entire scrollback buffer has been
filled - we need to detect when the view has wrapped around to the
current terminal offset.
The detection of when we've reached the bottom of the history is also
flawed, and only works when we overshoot the bottom with at least a
page.
Resizing the windows while in a view most likely doesn't work.
The view will not detect a wrapped around scrollback buffer. I.e. if
the user has scrolled back, and is stationary at a view, but there is
still output being produced. Then eventually the scrollback buffer
will wrap around. In this case, the correct thing to do is make the
view start following the beginning of the history. Right now it
doesn't, meaning once the scrollback buffer wraps around, you'll start
seeing command output...
The grid is now represented with an array of row *pointers*. Each row
contains an array of cells (the row's columns).
The main point of having row pointers is we can now move rows around
almost for free.
This is useful when scrolling with scroll margins for example, where
we previously had to copy the lines in the margins. Now it's just a
matter of swapping two pointers.
Vim, for example, changes the scroll region every time you scroll a
single line. Thus, resetting the damage queue is slow.
This reworks the damage handling of scroll updates:
* Split damage queue into two: one for scroll operations and one for
update/erase operations.
* Don't separate update/erase operations inside/outside the scroll
region
* Store the current scroll region in the scroll damage operation. This
allows us to stack multiple scroll operations with different scroll
regions.
* When updating update/erase operations after a scroll operation,
split the update/erase operations if necessary (the current scroll
operation may have a scroll region different from before, thus
forcing us to split existing update/erase operations.
* The renderer no longer erases after a scroll. The scroll operation
also adds an erase operation. This also means that erase operation
are subject to adjustments by later scroll operations.
This is largely untested, but existing scrolling code has been
converted to using a terminal-global scrolling region that is defined
as start-end of the scrollable region.
This is compared to the old code where the scrolling region where
defined in terms of marginals, counted in lines from top and from
bottom.
Instead of having each cell in the grid track it's own dirtiness, grid
operations now append "damage" to a list.
This list is consumed every time we render the grid.
This allows us to special case some operations, like erase (and in the
future, scroll).
