#90 flashing GUI indicator lights

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()