From 9d107da8d9b9380ec91d9a4509b7f19107f2a53b Mon Sep 17 00:00:00 2001
From: Mikayla Fischler <mikayla@ky8.io>
Date: Wed, 8 Jun 2022 14:16:05 -0400
Subject: [PATCH] #63 horizontal fill bar indicator

---
 graphics/elements/hbar.lua | 84 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 graphics/elements/hbar.lua

diff --git a/graphics/elements/hbar.lua b/graphics/elements/hbar.lua
new file mode 100644
index 0000000..f200bee
--- /dev/null
+++ b/graphics/elements/hbar.lua
@@ -0,0 +1,84 @@
+-- Horizontal Bar Graphics Element
+
+local util    = require("scada-common.util")
+
+local element = require("graphics.element")
+
+---@class hbar_args
+---@field bar_fg_bg cpair bar foreground/background colors
+---@field border? graphics_border
+---@field parent graphics_element
+---@field x? integer 1 if omitted
+---@field y? integer 1 if omitted
+---@field width? integer parent width if omitted
+---@field fg_bg cpair foreground/background colors
+
+-- new horizontal bar
+---@param args hbar_args
+local function hbar(args)
+    local bkg = ""
+    local last_num_bars = -1
+
+    -- create new graphics element base object
+    local e = element.new(args)
+
+    -- bar width is width - 5 characters for " 100%"
+    local bar_width = e.frame.w - 5
+
+    assert(bar_width > 0, "graphics.elements.hbar: too small for bar")
+
+    -- set background blit string
+    for _ = 1, bar_width do
+        bkg = bkg .. args.bar_fg_bg.blit_bkg
+    end
+
+    -- handle data changes
+    function e.on_update(fraction)
+        -- enforce minimum and maximum
+        if fraction < 0 then
+            fraction = 0.0
+        elseif fraction > 1 then
+            fraction = 1.0
+        end
+
+        -- compute number of bars
+        local num_bars = util.round((fraction * 100) / (bar_width * 2))
+
+        -- redraw bar if changed
+        if num_bars ~= last_num_bars then
+            last_num_bars = num_bars
+
+            local bar = ""
+            local spaces = ""
+
+            -- fill percentage
+            for _ = 1, num_bars / 2 do
+                spaces = spaces .. " "
+                bar = bar .. args.bar_fg_bg.blit_fgd
+            end
+
+            -- add fractional bar if needed
+            if num_bars % 2 == 1 then
+                spaces = spaces .. "\x95"
+                bar = bar .. args.bar_fg_bg.blit_fgd
+            end
+
+            -- pad background
+            for _ = 1, bar_width - ((num_bars / 2) + num_bars % 2) do
+                spaces = spaces .. " "
+                bar = bar .. args.bar_fg_bg.blit_bkg
+            end
+
+            e.window.setCursorPos(1, 1)
+            e.window.blit(spaces, bar, bkg)
+        end
+
+        -- update percentage
+        e.window.setCursorPos(bar_width + 1, 1)
+        e.window.write(util.sprintf("%3.0f%%", fraction * 100))
+    end
+
+    return e.get()
+end
+
+return hbar