Compare two screen buffers — diff

Computes the minimal set of horizontal runs of cells that must be rewritten to turn the screen old into new. Nearby runs on the same row are merged when rewriting the unchanged cells between them is cheaper than an extra cursor movement.

Usage

diff_screen(old, new, merge_gap = 3L)

Arguments

old, new: ScreenBuffer objects (old may be NULL).
merge_gap: Runs separated by at most this many unchanged cells are merged.

Value

A termr_patch: a list with full (logical), width, height and runs, a list of runs. Each run has y, x and vectors chars, fg, bg, attrs copied from new.

Details

If old is NULL or has different dimensions, the patch covers every non-blank cell of new and is marked full = TRUE; the renderer then clears the screen first.

Examples

a <- screen_buffer(10, 2)
b <- a$copy()
b$put_text(3, 2, "hi")
diff_screen(a, b)
#> <patch 10x2: 1 run(s), 2 cell(s)>