feat(w.c.conditional): Implement conditional container

This container allows showing or hiding a child widget based on a boolean
state property.

lib/wibox/container/conditional.lua

@@ -0,0 +1,109 @@
+---------------------------------------------------------------------------
+-- A simple container that will hide its child widget based a
+-- boolean state variable.
+--
+--@DOC_wibox_container_conditional_comparison_EXAMPLE@
+--
+-- @author Lucas Schwiderski
+-- @copyright 2022 Lucas Schwiderski
+-- @containermod wibox.container.conditional
+-- @supermodule wibox.widget.base
+---------------------------------------------------------------------------
+
+local base = require("wibox.widget.base")
+local gtable = require("gears.table")
+local gobject = require("gears.object")
+
+local conditional = { mt = {} }
+
+
+function conditional:fit(context, width, height)
+    if not self._private.state then
+        return 0, 0
+    end
+
+    return base.fit_widget(self, context, self._private.widget, width, height)
+end
+
+
+function conditional:layout(_, width, height)
+    if not self._private.state then
+        return {}
+    end
+
+    return { base.place_widget_at(self._private.widget, 0, 0, width, height) }
+end
+
+
+--- The conditional state.
+--
+-- The child widget is shown or hidden based on this state.
+--
+-- @property state
+-- @tparam boolean state
+-- @propemits true false
+
+function conditional:set_state(state)
+    state = not (not state)
+
+    if self._private.state == state then
+        return
+    end
+
+    self._private.state = state
+
+    self:emit_signal("widget::layout_changed")
+    self:emit_signal("property::state", state)
+end
+
+function conditional:get_state()
+    return self._private.state
+end
+
+
+--- The widget to be displayed based on the state.
+-- @property widget
+-- @tparam widget widget
+-- @propemits true false
+-- @interface container
+
+conditional.set_widget = base.set_widget_common
+function conditional:get_widget()
+    return self._private.widget
+end
+
+
+function conditional:set_children(widgets)
+    self:set_widget(widgets[1])
+end
+
+function conditional:get_children()
+    return { self._private.widget }
+end
+
+
+local function new(widget, state)
+    local ret = base.make_widget(nil, nil, { enable_properties = true})
+
+    gtable.crush(ret, conditional, true)
+    ret.widget_name = gobject.modulename(2)
+
+    ret._private.widget = widget
+
+    if type(state) == "boolean" then
+        ret._private.state = state
+    else
+        ret._private.state = true
+    end
+
+    return ret
+end
+
+
+function conditional.mt:__call(...)
+    return new(...)
+end
+
+return setmetatable(conditional, conditional.mt)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

lib/wibox/container/init.lua

@@ -18,6 +18,7 @@ return setmetatable({
     arcchart = require("wibox.container.arcchart");
     place = require("wibox.container.place");
     tile = require("wibox.container.tile");
+    conditional = require("wibox.container.conditional");
 }, {__call = function(_, args) return base.make_widget_declarative(args) end})
 
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

spec/wibox/container/conditional_spec.lua

@@ -0,0 +1,48 @@
+---------------------------------------------------------------------------
+-- @author Lucas Schwiderski
+-- @copyright 2022 Lucas Schwiderski
+---------------------------------------------------------------------------
+
+local conditional = require("wibox.container.conditional")
+local utils = require("wibox.test_utils")
+local base = require("wibox.widget.base")
+local p = require("wibox.widget.base").place_widget_at
+
+describe("wibox.container.conditional", function()
+    it("implements the common API", function()
+        utils.test_container(conditional())
+    end)
+
+    describe("constructor", function()
+        it("applies arguments", function()
+            local inner = base.empty_widget()
+            local state = false
+            local widget = conditional(inner, state)
+
+            assert.is.equal(inner, widget.widget)
+            assert.is.equal(state, widget.state)
+        end)
+
+        it("defaults to state == true", function()
+            local widget = conditional()
+            assert.is_true(widget.state)
+        end)
+    end)
+
+    it("hides the child widget when state == false", function()
+        local inner = utils.widget_stub(10, 10)
+        local widget = conditional(inner)
+
+        assert.widget_fit(widget, { 10, 10 }, { 10, 10 })
+        assert.widget_layout(widget, { 10, 10 }, {
+            p(inner,  0,  0, 10, 10),
+        })
+
+        widget.state = false
+
+        assert.widget_fit(widget, { 10, 10 }, { 0, 0 })
+        assert.widget_layout(widget, { 0, 0 }, {})
+    end)
+end)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

tests/examples/wibox/container/conditional/comparison.lua

@@ -0,0 +1,62 @@
+--DOC_HIDE_START --DOC_GEN_IMAGE
+local parent = ...
+local wibox = require("wibox")
+local beautiful = require("beautiful")
+
+parent.spacing = 10
+
+parent:add(wibox.widget {
+    layout = wibox.layout.fixed.vertical,
+    spacing = 2,
+    {
+        markup = "state == <b>true</b>",
+        widget = wibox.widget.textbox
+    },
+--DOC_HIDE_END
+{
+    {
+        {
+            text = "Hello, World!",
+            widget = wibox.widget.textbox,
+        },
+        state = true,
+        widget = wibox.container.conditional,
+    },
+    bg = beautiful.bg_normal,
+    widget = wibox.container.background,
+},
+--DOC_HIDE_START
+})
+
+parent:add(wibox.widget {
+    layout = wibox.layout.fixed.vertical,
+    spacing = 2,
+    {
+        markup = "state == <b>false</b>",
+        widget = wibox.widget.textbox
+    },
+--DOC_HIDE_END
+{
+    { --DOC_HIDE
+    {
+        {
+            text = "Hello, World!",
+            widget = wibox.widget.textbox,
+        },
+        state = false,
+        widget = wibox.container.conditional,
+    },
+--DOC_HIDE_START
+    strategy = "min",
+    width = 100,
+    height = 18,
+    widget = wibox.container.constraint,
+    },
+--DOC_HIDE_END
+    bg = beautiful.bg_normal,
+    widget = wibox.container.background,
+},
+--DOC_HIDE_START
+})
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80