1 files changed, 196 insertions, 0 deletions
diff --git a/lua/colorizer/buffer_utils.lua b/lua/colorizer/buffer_utils.lua
new file mode 100644
index 0000000..0f8517f
--- /dev/null
+++ b/lua/colorizer/buffer_utils.lua
@@ -0,0 +1,196 @@
+---Helper functions to highlight buffer smartly
+--@module colorizer.buffer_utils
+local api = vim.api
+local buf_set_virtual_text = api.nvim_buf_set_extmark
+local buf_get_lines = api.nvim_buf_get_lines
+local create_namespace = api.nvim_create_namespace
+local clear_namespace = api.nvim_buf_clear_namespace
+local set_highlight = api.nvim_set_hl
+
+local color_utils = require "colorizer.color_utils"
+local color_is_bright = color_utils.color_is_bright
+
+local matcher_utils = require "colorizer.matcher_utils"
+local make_matcher = matcher_utils.make_matcher
+
+--- Default namespace used in `highlight_buffer` and `colorizer.attach_to_buffer`.
+-- @see highlight_buffer
+-- @see colorizer.attach_to_buffer
+local DEFAULT_NAMESPACE = create_namespace "colorizer"
+local HIGHLIGHT_NAME_PREFIX = "colorizer"
+--- Highlight mode which will be use to render the colour
+local HIGHLIGHT_MODE_NAMES = {
+  background = "mb",
+  foreground = "mf",
+  virtualtext = "mv",
+}
+local HIGHLIGHT_CACHE = {}
+
+--- Make a deterministic name for a highlight given these attributes
+local function make_highlight_name(rgb, mode)
+  return table.concat({ HIGHLIGHT_NAME_PREFIX, HIGHLIGHT_MODE_NAMES[mode], rgb }, "_")
+end
+
+local function create_highlight(rgb_hex, options)
+  local mode = options.mode or "background"
+  -- TODO validate rgb format?
+  rgb_hex = rgb_hex:lower()
+  local cache_key = table.concat({ HIGHLIGHT_MODE_NAMES[mode], rgb_hex }, "_")
+  local highlight_name = HIGHLIGHT_CACHE[cache_key]
+
+  -- Look up in our cache.
+  if highlight_name then
+    return highlight_name
+  end
+
+  -- convert from #fff to #ffffff
+  if #rgb_hex == 3 then
+    rgb_hex = table.concat {
+      rgb_hex:sub(1, 1):rep(2),
+      rgb_hex:sub(2, 2):rep(2),
+      rgb_hex:sub(3, 3):rep(2),
+    }
+  end
+
+  -- Create the highlight
+  highlight_name = make_highlight_name(rgb_hex, mode)
+  if mode == "foreground" then
+    set_highlight(0, highlight_name, { fg = "#" .. rgb_hex })
+  else
+    local rr, gg, bb = rgb_hex:sub(1, 2), rgb_hex:sub(3, 4), rgb_hex:sub(5, 6)
+    local r, g, b = tonumber(rr, 16), tonumber(gg, 16), tonumber(bb, 16)
+    local fg_color
+    if color_is_bright(r, g, b) then
+      fg_color = "Black"
+    else
+      fg_color = "White"
+    end
+    set_highlight(0, highlight_name, { fg = fg_color, bg = "#" .. rgb_hex })
+  end
+  HIGHLIGHT_CACHE[cache_key] = highlight_name
+  return highlight_name
+end
+
+local function add_highlight(options, buf, ns, data)
+  if vim.tbl_contains({ "foreground", "background" }, options.mode) then
+    for linenr, hls in pairs(data) do
+      for _, hl in ipairs(hls) do
+        api.nvim_buf_add_highlight(buf, ns, hl.name, linenr, hl.range[1], hl.range[2])
+      end
+    end
+  elseif options.mode == "virtualtext" then
+    for linenr, hls in pairs(data) do
+      for _, hl in ipairs(hls) do
+        buf_set_virtual_text(0, ns, linenr, hl.range[2], {
+          end_col = hl.range[2],
+          virt_text = { { options.virtualtext or "■", hl.name } },
+        })
+      end
+    end
+  end
+end
+
+--- Highlight the buffer region.
+-- Highlight starting from `line_start` (0-indexed) for each line described by `lines` in the
+-- buffer `buf` and attach it to the namespace `ns`.
+---@param buf number: buffer id
+---@param ns number: The namespace id. Default is DEFAULT_NAMESPACE. Create it with `vim.api.create_namespace`
+---@param lines table: the lines to highlight from the buffer.
+---@param line_start number: line_start should be 0-indexed
+---@param options table: Configuration options as described in `setup`
+local function highlight_buffer(buf, ns, lines, line_start, options)
+  if buf == 0 or buf == nil then
+    buf = api.nvim_get_current_buf()
+  end
+
+  ns = ns or DEFAULT_NAMESPACE
+  local loop_parse_fn = make_matcher(options)
+  if not loop_parse_fn then
+    return false
+  end
+
+  local data = {}
+  local mode = options.mode == "background" and { mode = "background" } or { mode = "foreground" }
+  for current_linenum, line in ipairs(lines) do
+    current_linenum = current_linenum - 1 + line_start
+    -- Upvalues are options and current_linenum
+    local i = 1
+    while i < #line do
+      local length, rgb_hex = loop_parse_fn(line, i)
+      if length then
+        local name = create_highlight(rgb_hex, mode)
+        local d = data[current_linenum] or {}
+        table.insert(d, { name = name, range = { i - 1, i + length - 1 } })
+        data[current_linenum] = d
+        i = i + length
+      else
+        i = i + 1
+      end
+    end
+  end
+  add_highlight(options, buf, ns, data)
+end
+
+local BUFFER_LINES = {}
+--- Rehighlight the buffer if colorizer is active
+---@param buf number: Buffer number
+---@param options table: Buffer options
+local function rehighlight_buffer(buf, options)
+  if buf == 0 or buf == nil then
+    buf = api.nvim_get_current_buf()
+  end
+
+  local ns = DEFAULT_NAMESPACE
+
+  if not BUFFER_LINES[buf] then
+    BUFFER_LINES[buf] = {}
+  end
+
+  local a = api.nvim_buf_call(buf, function()
+    return {
+      vim.fn.line "w0",
+      vim.fn.line "w$",
+    }
+  end)
+  local min, max
+  local new_min, new_max = a[1] - 1, a[2]
+  local old_min, old_max = BUFFER_LINES[buf]["min"], BUFFER_LINES[buf]["max"]
+
+  if old_min and old_max then
+    -- Triggered for TextChanged autocmds
+    -- TODO: Find a way to just apply highlight to changed text lines
+    if old_max == new_max then
+      min, max = new_min, new_max
+    -- Triggered for WinScrolled autocmd - Scroll Down
+    elseif old_max < new_max then
+      min = old_max
+      max = new_max
+    -- Triggered for WinScrolled autocmd - Scroll Up
+    elseif old_max > new_max then
+      min = new_min
+      max = new_min + (old_max - new_max)
+    end
+    -- just in case a long jump was made
+    if max - min > new_max - new_min then
+      min = new_min
+      max = new_max
+    end
+  end
+
+  min = min or new_min
+  max = max or new_max
+  clear_namespace(buf, ns, min, max)
+  local lines = buf_get_lines(buf, min, max, false)
+  highlight_buffer(buf, ns, lines, min, options)
+  -- store current window position to be used later to incremently highlight
+  BUFFER_LINES[buf]["max"] = new_max
+  BUFFER_LINES[buf]["min"] = new_min
+end
+
+--- @export
+return {
+  DEFAULT_NAMESPACE = DEFAULT_NAMESPACE,
+  HIGHLIGHT_MODE_NAMES = HIGHLIGHT_MODE_NAMES,
+  rehighlight_buffer = rehighlight_buffer,
+  highlight_buffer = highlight_buffer,
+}