#90 flashing GUI indicator lights

graphics/core.lua

@@ -4,6 +4,10 @@
 
 local core = {}
 
+local flasher = require("graphics.flasher")
+
+core.flasher = flasher
+
 local events = {}
 
 ---@class monitor_touch

graphics/elements/indicators/light.lua

@@ -1,11 +1,15 @@
 -- Indicator Light Graphics Element
 
 local element = require("graphics.element")
+local flasher = require("graphics.flasher")
+local util    = require("scada-common.util")
 
 ---@class indicator_light_args
 ---@field label string indicator label
 ---@field colors cpair on/off colors (a/b respectively)
 ---@field min_label_width? integer label length if omitted
+---@field flash? boolean whether to flash on true rather than stay on
+---@field period? PERIOD flash period
 ---@field parent graphics_element
 ---@field id? string element id
 ---@field x? integer 1 if omitted
@@ -19,25 +23,62 @@ local function indicator_light(args)
     assert(type(args.label) == "string", "graphics.elements.indicators.light: label is a required field")
     assert(type(args.colors) == "table", "graphics.elements.indicators.light: colors is a required field")
 
+    if args.flash then
+        assert(util.is_int(args.period), "graphics.elements.indicators.light: period is a required field if flash is enabled")
+    end
+
     -- single line
     args.height = 1
 
     -- determine width
     args.width = math.max(args.min_label_width or 1, string.len(args.label)) + 2
 
+    -- flasher state
+    local flash_on = true
+
     -- create new graphics element base object
     local e = element.new(args)
 
+    -- called by flasher when enabled
+    local function flash_callback()
+        e.window.setCursorPos(1, 1)
+    
+        if flash_on then
+            e.window.blit(" \x95", "0" .. args.colors.blit_a, args.colors.blit_a .. e.fg_bg.blit_bkg)
+        else
+            e.window.blit(" \x95", "0" .. args.colors.blit_b, args.colors.blit_b .. e.fg_bg.blit_bkg)
+        end
+
+        flash_on = not flash_on
+    end
+
+    -- enable light or start flashing
+    local function enable()
+        if args.flash then
+            flash_on = true
+            flasher.start(flash_callback, args.period)
+        else
+            e.window.setCursorPos(1, 1)
+            e.window.blit(" \x95", "0" .. args.colors.blit_a, args.colors.blit_a .. e.fg_bg.blit_bkg)
+        end
+    end
+
+    -- disable light or stop flashing
+    local function disable()
+        if args.flash then
+            flash_on = false
+            flasher.stop(flash_callback)
+        end
+
+        e.window.setCursorPos(1, 1)
+        e.window.blit(" \x95", "0" .. args.colors.blit_b, args.colors.blit_b .. e.fg_bg.blit_bkg)
+    end
+
     -- on state change
     ---@param new_state boolean indicator state
     function e.on_update(new_state)
         e.value = new_state
-        e.window.setCursorPos(1, 1)
-        if new_state then
-            e.window.blit(" \x95", "0" .. args.colors.blit_a, args.colors.blit_a .. e.fg_bg.blit_bkg)
-        else
-            e.window.blit(" \x95", "0" .. args.colors.blit_b, args.colors.blit_b .. e.fg_bg.blit_bkg)
-        end
+        if new_state then enable() else disable() end
     end
 
     -- set indicator state
@@ -46,6 +87,7 @@ local function indicator_light(args)
 
     -- write label and initial indicator light
     e.on_update(false)
+    e.window.setCursorPos(3, 1)
     e.window.write(args.label)
 
     return e.get()

graphics/flasher.lua

@@ -0,0 +1,82 @@
+--
+-- Indicator Light Flasher
+--
+
+local tcd = require("scada-common.tcallbackdsp")
+
+local flasher = {}
+
+-- note: no additional call needs to be made in a main loop as this class automatically uses the TCD to operate
+
+---@alias PERIOD integer
+local PERIOD = {
+    BLINK_250_MS = 1,
+    BLINK_500_MS = 2,
+    BLINK_1000_MS = 3
+}
+
+flasher.PERIOD = PERIOD
+
+local active = false
+local registry = { {}, {}, {} } -- one registry table per period
+local callback_counter = 0
+
+-- start the flasher task
+function flasher.init()
+    active = true
+    registry = { {}, {}, {} }
+    flasher.callback_250ms()
+end
+
+-- clear all blinking indicators and stop the flasher task
+function flasher.clear()
+    active = false
+    registry = { {}, {}, {} }
+end
+
+-- register a function to be called on the selected blink period
+--
+-- times are not strictly enforced, but all with a given period will be set at the same time
+---@param f function function to call each period
+---@param period PERIOD time period option (1, 2, or 3)
+function flasher.start(f, period)
+    if type(registry[period]) == "table" then
+        table.insert(registry[period], f)
+    end
+end
+
+-- stop a function from being called at the blink period
+---@param f function function callback registered
+function flasher.stop(f)
+    for i = 1, #registry do
+        for j = 1, #registry[i] do
+            if registry[i][j] == f then
+                registry[i][j] = nil
+                break
+            end
+        end
+    end
+end
+
+-- blink registered indicators
+--
+-- this assumes it is called every 250ms, it does no checking of time on its own
+function flasher.callback_250ms()
+    if active then
+        for _, f in pairs(registry[PERIOD.BLINK_250_MS]) do f() end
+
+        if callback_counter % 2 == 0 then
+            for _, f in pairs(registry[PERIOD.BLINK_500_MS]) do f() end
+        end
+
+        if callback_counter % 4 == 0 then
+            for _, f in pairs(registry[PERIOD.BLINK_1000_MS]) do f() end
+        end
+
+        callback_counter = callback_counter + 1
+
+        tcd.dispatch(0.25, flasher.callback_250ms)
+    end
+end
+
+return flasher