From 8da986ea877b07a5eb117446f410f2a7fc8cd9cb Mon Sep 17 00:00:00 2001 From: bfredl Date: Wed, 13 Sep 2023 13:39:18 +0200 Subject: refactor(grid): change schar_T representation to be more compact Previously, a screen cell would occupy 28+4=32 bytes per cell as we always made space for up to MAX_MCO+1 codepoints in a cell. As an example, even a pretty modest 50*80 screen would consume 50*80*2*32 = 256000, i e a quarter megabyte With the factor of two due to the TUI side buffer, and even more when using msg_grid and/or ext_multigrid. This instead stores a 4-byte union of either: - a valid UTF-8 sequence up to 4 bytes - an escape char which is invalid UTF-8 (0xFF) plus a 24-bit index to a glyph cache This avoids allocating space for huge composed glyphs _upfront_, while still keeping rendering such glyphs reasonably fast (1 hash table lookup + one plain index lookup). If the same large glyphs are using repeatedly on the screen, this is still a net reduction of memory/cache consumption. The only case which really gets worse is if you blast the screen full with crazy emojis and zalgo text and even this case only leads to 4 extra bytes per char. When only <= 4-byte glyphs are used, plus the 4-byte attribute code, i e 8 bytes in total there is a factor of four reduction of memory use. Memory which will be quite hot in cache as the screen buffer is scanned over in win_line() buffer text drawing A slight complication is that the representation depends on host byte order. I've tested this manually by compling and running this in qemu-s390x and it works fine. We might add a qemu based solution to CI at some point. --- runtime/lua/vim/_meta/api.lua | 3 +++ 1 file changed, 3 insertions(+) (limited to 'runtime/lua/vim/_meta/api.lua') diff --git a/runtime/lua/vim/_meta/api.lua b/runtime/lua/vim/_meta/api.lua index 6573c68493..c0c8cabfb9 100644 --- a/runtime/lua/vim/_meta/api.lua +++ b/runtime/lua/vim/_meta/api.lua @@ -79,6 +79,9 @@ function vim.api.nvim__id_float(flt) end --- @return any[] function vim.api.nvim__inspect_cell(grid, row, col) end +--- @private +function vim.api.nvim__invalidate_glyph_cache() end + --- @private --- @return any[] function vim.api.nvim__runtime_inspect() end -- cgit