input-method-indicator.lua

-- **************************************************
-- 输入法指示器
-- **************************************************

-- --------------------------------------------------
-- 指示器高度
local HEIHGT = 5
-- 指示器透明度
local ALPHA = 1
-- 多个颜色之间线性渐变
local ALLOW_LINEAR_GRADIENT = false
-- 指示器颜色
local IME_TO_COLORS = {
  -- 系统自带简中输入法
  ['com.apple.inputmethod.SCIM.ITABC'] = {
    { hex = '#dc2626' },
    -- { hex = '#eab308' },
    -- { hex = '#0ea5e9' }
  }
}
-- --------------------------------------------------

local canvases = {}
local lastSourceID = nil

-- 绘制指示器
local function draw(colors)
  local screens = hs.screen.allScreens()

  for i, screen in ipairs(screens) do
    local frame = screen:fullFrame()

    local canvas = hs.canvas.new({ x = frame.x, y = frame.y, w = frame.w, h = HEIHGT })
    canvas:level(hs.canvas.windowLevels.overlay)
    canvas:behavior(hs.canvas.windowBehaviors.canJoinAllSpaces)
    canvas:alpha(ALPHA)

    if ALLOW_LINEAR_GRADIENT and #colors > 1 then
      local rect = {
        type = 'rectangle',
        action = 'fill',
        fillGradient = 'linear',
        fillGradientColors = colors,
        frame = { x = 0, y = 0, w = frame.w, h = HEIHGT }
      }
      canvas[1] = rect
    else
      local cellW = frame.w / #colors

      for j, color in ipairs(colors) do
        local startX = (j - 1) * cellW
        local startY = 0
        local rect = {
          type = 'rectangle',
          action = 'fill',
          fillColor = color,
          frame = { x = startX, y = startY, w = cellW, h = HEIHGT }
        }
        canvas[j] = rect
      end
    end

    canvas:show()
    canvases[i] = canvas
  end
end

-- 清除 canvas 上的内容
local function clear()
  for _, canvas in ipairs(canvases) do
    canvas:delete()
  end
  canvases = {}
end

-- 更新 canvas 显示
local function update(sourceID)
  clear()

  local colors = IME_TO_COLORS[sourceID or hs.keycodes.currentSourceID()]

  if colors then
    draw(colors)
  end
end

local function handleInputSourceChanged()
  local currentSourceID = hs.keycodes.currentSourceID()

  if lastSourceID ~= currentSourceID then
    update(currentSourceID)
    lastSourceID = currentSourceID
  end
end

-- 输入法变化事件监听
-- 通过 hs.keycodes.inputSourceChanged 方式监听有时候不触发，直接监听系统事件可以解决，
-- 参考 https://github.com/Hammerspoon/hammerspoon/issues/1499）
imi_dn = hs.distributednotifications.new(
  handleInputSourceChanged,
  -- or 'AppleSelectedInputSourcesChangedNotification'
  'com.apple.Carbon.TISNotifySelectedKeyboardInputSourceChanged'
)
-- 每秒同步一次，避免由于错过事件监听导致状态不同步
imi_indicatorSyncTimer = hs.timer.new(1, handleInputSourceChanged)
-- 屏幕变化时候重新渲染
imi_screenWatcher = hs.screen.watcher.new(update)

imi_dn:start()
imi_indicatorSyncTimer:start()
imi_screenWatcher:start()

-- 初始执行一次
update()