feat(dim): added dim plugin

lua/snacks/dim.lua

@@ -0,0 +1,141 @@
+---@class snacks.dim
+---@overload fun(opts: snacks.dim.Config)
+local M = setmetatable({}, {
+  __call = function(M, ...)
+    return M.enable(...)
+  end,
+})
+
+---@class snacks.dim.Config
+local defaults = {
+  ---@type snacks.scope.Config
+  scope = {
+    min_size = 5,
+    max_size = 20,
+    siblings = true,
+  },
+  -- animate scopes. Enabled by default for Neovim >= 0.10
+  -- Works on older versions but has to trigger redraws during animation.
+  ---@type snacks.animate.Config|{enabled?: boolean}
+  animate = {
+    enabled = vim.fn.has("nvim-0.10") == 1,
+    easing = "outQuad",
+    duration = {
+      step = 20, -- ms per step
+      total = 300, -- maximum duration
+    },
+  },
+  enabled = function(buf)
+    return vim.g.snacks_dim ~= false and vim.b[buf].snacks_dim ~= false and vim.bo[buf].buftype == ""
+  end,
+}
+
+M.enabled = false
+local ns = vim.api.nvim_create_namespace("snacks_dim")
+local scopes ---@type snacks.scope.Listener?
+local scopes_anim = {} ---@type table<number, {from:number, to:number, buf:number}>
+
+Snacks.util.set_hl({
+  [""] = "DiagnosticUnnecessary",
+}, { prefix = "SnacksDim", default = true })
+
+--- Called during every redraw cycle, so it should be fast.
+--- Everything that can be cached should be cached.
+---@param win number
+---@param buf number
+---@param top number -- 1-indexed
+---@param bottom number -- 1-indexed
+function M.on_win(win, buf, top, bottom)
+  local scope = scopes and scopes:get(win)
+  if not scope then
+    return
+  end
+  local function add(l)
+    vim.api.nvim_buf_set_extmark(buf, ns, l - 1, 0, {
+      end_row = l,
+      end_col = 0,
+      hl_group = "SnacksDim",
+      ephemeral = true,
+    })
+  end
+  local from = M.animating and scopes_anim[win] and scopes_anim[win].from or scope.from
+  local to = M.animating and scopes_anim[win] and scopes_anim[win].to or scope.to
+  for l = top, math.min(from - 1, bottom) do
+    add(l)
+  end
+  for l = math.max(to + 1, top), bottom do
+    add(l)
+  end
+end
+
+---@param opts? snacks.dim.Config
+function M.enable(opts)
+  if M.enabled then
+    return
+  end
+  opts = Snacks.config.get("dim", defaults, opts)
+
+  M.enabled = true
+
+  if opts.animate then
+    M.animating = true
+  end
+
+  -- setup decoration provider
+  vim.api.nvim_set_decoration_provider(ns, {
+    on_win = function(_, win, buf, top, bottom)
+      if M.enabled and opts.enabled(buf) then
+        M.on_win(win, buf, top + 1, bottom + 1)
+      end
+    end,
+  })
+
+  scopes = scopes
+    or Snacks.scope.attach(function(win, buf, scope, prev)
+      if not M.animating then
+        Snacks.util.redraw(win)
+      else
+        if not (scopes_anim[win] and scopes_anim[win].buf == buf) then
+          local info = vim.fn.getwininfo(win)[1]
+          scopes_anim[win] = {
+            from = info.topline,
+            to = info.botline,
+            buf = buf,
+          }
+        end
+
+        Snacks.animate.animate(scopes_anim[win].from, scope.from, function(v)
+          scopes_anim[win].from = v
+          Snacks.util.redraw(win)
+        end, vim.tbl_extend("keep", { int = true, id = "snacks_dim_from_" .. win }, opts.animate))
+
+        Snacks.animate.animate(scopes_anim[win].to, scope.to, function(v)
+          scopes_anim[win].to = v
+          Snacks.util.redraw(win)
+        end, vim.tbl_extend("keep", { int = true, id = "snacks_dim_to_" .. win }, opts.animate))
+      end
+    end, opts.scope)
+  if not scopes.enabled then
+    scopes:enable()
+  end
+end
+
+-- Disable dimming
+function M.disable()
+  if not M.enabled then
+    return
+  end
+  M.enabled = false
+  if scopes and scopes.enabled then
+    scopes:disable()
+  end
+  scopes_anim = {}
+  vim.cmd([[redraw!]])
+end
+
+-- Animate scope changes
+function M.animate()
+  M.animating = not M.animating
+end
+
+return M