#63 button control element

graphics/elements/button.lua

@@ -0,0 +1,58 @@
+-- Button Graphics Element
+
+local tcd     = require("scada-common.tcallbackdsp")
+
+local element = require("graphics.element")
+
+---@class button_args
+---@field text string button text
+---@field callback function function to call on touch
+---@field min_width? integer text length + 2 if omitted
+---@field active_fg_bg? cpair foreground/background colors when pressed
+---@field parent graphics_element
+---@field x? integer 1 if omitted
+---@field y? integer 1 if omitted
+---@field height? integer parent height if omitted
+---@field gframe? graphics_frame frame instead of x/y/width/height
+---@field fg_bg cpair foreground/background colors
+
+-- new button
+---@param args button_args
+local function button(args)
+    local text_width = string.len(args.text)
+    args.width = math.max(text_width + 2, args.min_width)
+
+    -- create new graphics element base object
+    local e = element.new(args)
+
+    local h_pad = math.floor((e.frame.w - text_width) / 2)
+    local v_pad = math.floor(e.frame.h / 2) + 1
+
+    -- write the button text
+    e.window.setCursorPos(h_pad, v_pad)
+    e.write(args.text)
+
+    -- handle touch
+    function e.handle_touch(event)
+        if args.active_fg_bg ~= nil then
+            -- show as pressed
+            e.window.setTextColor(args.active_fg_bg.fgd)
+            e.window.setBackgroundColor(args.active_fg_bg.bkg)
+            e.window.redraw()
+
+            -- show as unpressed in 0.5 seconds
+            tcd.dispatch(0.5, function ()
+                e.window.setTextColor(e.fg_bg.fgd)
+                e.window.setBackgroundColor(e.fg_bg.bkg)
+                e.window.redraw()
+            end)
+        end
+
+        -- call the touch callback
+        args.callback()
+    end
+
+    return e.get()
+end
+
+return button