feat: implement custom status column with gradient highlights

lua/config/statuscolumn.lua

@@ -0,0 +1,106 @@
+-- Setup gradient line number column
+
+-- Table to hold hex color values for easy reference
+local colors = {
+  statusLineNrCurrent = "#b3befe",
+  statusLineNrDefault = "#444659",
+  fallbackColor = "#808080" -- Fallback gray if the group doesn't exist
+}
+
+--- Calculate a color gradient between two colors.
+-- @param base_color (string) The starting color in hex format (e.g., '#RRGGBB').
+-- @param target_color (string) The ending color in hex format (e.g., '#RRGGBB').
+-- @param max_steps (number) The total number of steps in the gradient.
+-- @param step (number) The current step in the gradient.
+-- @return (string) The interpolated color in hex format.
+local function calculate_gradient(base_color, target_color, max_steps, step)
+  -- Parse the base and target colors into RGB components
+  local br, bg, bb =
+    tonumber(base_color:sub(2, 3), 16),
+    tonumber(base_color:sub(4, 5), 16),
+    tonumber(base_color:sub(6, 7), 16)
+
+  local tr, tg, tb =
+    tonumber(target_color:sub(2, 3), 16),
+    tonumber(target_color:sub(4, 5), 16),
+    tonumber(target_color:sub(6, 7), 16)
+
+  -- Calculate the blending factor
+  local factor = step / max_steps
+
+  -- Interpolate between the base and target colors based on the blending factor
+  local r = math.floor(br + (tr - br) * factor)
+  local g = math.floor(bg + (tg - bg) * factor)
+  local b = math.floor(bb + (tb - bb) * factor)
+
+  return string.format('#%02X%02X%02X', r, g, b) -- Return the new color as a string
+end
+
+--- Get the foreground color of a highlight group.
+-- @param group (string) The name of the highlight group.
+-- @return (string) The foreground color in hex format or a fallback gray color.
+local function get_highlight_fg(group)
+  local hl = vim.api.nvim_get_hl(0, { name = group })
+  if hl and hl.fg then
+    return string.format('#%06X', hl.fg) -- Convert the integer color to hex
+  else
+    return colors.fallbackColor -- Use fallback gray if the group doesn't exist
+  end
+end
+
+--- Set up gradient highlights for a specified group.
+-- @param base_color (string) The starting color for the gradient.
+-- @param group_name_prefix (string) The prefix for the highlight group names.
+-- @param max_steps (number) The total number of steps for the gradient.
+local function setup_gradient_highlights(base_color, group_name_prefix, max_steps)
+  local target_color = get_highlight_fg('StatusLineNrDefault') -- Get the default color for interpolation
+  for step = 1, max_steps do
+    local color = calculate_gradient(base_color, target_color, max_steps, step) -- Get the gradient color
+    vim.api.nvim_set_hl(
+      0,
+      group_name_prefix .. step,
+      { fg = color, bg = 'NONE' } -- Set the highlight with foreground color and no background
+    )
+  end
+end
+
+-- Define highlight groups for current and default status line numbers
+vim.api.nvim_set_hl(0, 'StatusLineNrCurrent', { fg = colors.statusLineNrCurrent, bg = 'NONE', bold = true })
+vim.api.nvim_set_hl(0, 'StatusLineNrDefault', { fg = colors.statusLineNrDefault, bg = 'NONE' })
+
+-- Set up gradient highlights for lines above and below the cursor
+setup_gradient_highlights(colors.statusLineNrCurrent, 'StatusLineNrAbove', 10)
+setup_gradient_highlights(colors.statusLineNrCurrent, 'StatusLineNrBelow', 10)
+
+-- Custom status column for displaying line number gradients
+_G.CustomStatusColumn = function()
+  local lnum = vim.v.lnum -- Current line number
+  local cursor_lnum = vim.fn.line('.') -- Current cursor line number
+  local max_gradient_steps = 10 -- Maximum steps in gradient
+
+  -- Use the plugin's original status column
+  local original_statuscolumn = require('snacks.statuscolumn').get()
+
+  -- Highlight for the current line
+  if lnum == cursor_lnum then
+    return '%#StatusLineNrCurrent#' .. original_statuscolumn .. '%*'
+  end
+
+  -- Highlight for lines above the cursor
+  if lnum < cursor_lnum and (cursor_lnum - lnum) <= max_gradient_steps then
+    local step = cursor_lnum - lnum
+    return '%#StatusLineNrAbove' .. step .. '#' .. original_statuscolumn .. '%*'
+  end
+
+  -- Highlight for lines below the cursor
+  if lnum > cursor_lnum and (lnum - cursor_lnum) <= max_gradient_steps then
+    local step = lnum - cursor_lnum
+    return '%#StatusLineNrBelow' .. step .. '#' .. original_statuscolumn .. '%*'
+  end
+
+  -- Default case for other lines
+  return '%#StatusLineNrDefault#' .. original_statuscolumn .. '%*'
+end
+
+-- Set the custom status column to be used
+vim.o.statuscolumn = [[%!v:lua.CustomStatusColumn()]]