Add scroll_container widget

config/awesome/noodle/scroll_container.lua

@@ -0,0 +1,67 @@
+local awful = require("awful")
+local gears = require("gears")
+local wibox = require("wibox")
+local beautiful = require("beautiful")
+local helpers = require("helpers")
+
+local naughty = require("naughty")
+
+local scroll_container = {}
+
+scroll_container.new = function(orientation, max_visible_children, loop)
+    local container = wibox.widget {
+        layout = wibox.layout.fixed[orientation]
+    }
+
+    local scroll_start_index = 1
+
+    -- BUG(?): For some reason the layout_changed signal is fired twice when
+    -- container children change. During the first event, container.children is
+    -- always empty so we do not really mind since the loop terminate instantly.
+    container:connect_signal("widget::layout_changed", function()
+        scroll_start_index = 1
+        for i, task in ipairs(container.children) do
+            if i > max_visible_children then
+                container.children[i].visible = false
+            end
+        end
+    end)
+
+
+    local function update_scroll(scroll_start_index)
+        for i=1,(scroll_start_index - 1) do
+            container.children[i].visible = false
+        end
+
+        for i=scroll_start_index,(scroll_start_index + max_visible_children - 1) do
+            container.children[i].visible = true
+        end
+
+        for i=(scroll_start_index + max_visible_children), #(container.children) do
+            container.children[i].visible = false
+        end
+    end
+
+    -- Number can be both positive (scroll forwards) or negative (scroll
+    -- backwards).
+    if loop then
+        function container:scroll(number)
+            scroll_start_index = (scroll_start_index + number - 1) % (#(container.children) - max_visible_children + 1) + 1
+            update_scroll(scroll_start_index)
+        end
+    else
+        function container:scroll(number)
+            scroll_start_index = scroll_start_index + number
+            if scroll_start_index < 1 then
+                scroll_start_index = 1
+            elseif scroll_start_index > (#(container.children) - max_visible_children + 1) then
+                scroll_start_index = #(container.children) - max_visible_children + 1
+            end
+            update_scroll(scroll_start_index)
+        end
+    end
+
+    return container
+end
+
+return scroll_container