layout.fixed: Add methods to manipulate the layout after creation

Until now, this layout was "append only". There was no official
APIs to remove, replace, insert and swap widgets. This is fine
for the usual wibox + sensors widget used by the majority of
users, but lack flexibility necessary to use the layout system
to place dynamic elements such as clients.

The methods introduced by this commit are also recursive. This
allow widgets to be decorated, wrapped and splitted without
having to add boilerplate code everywhere.

lib/wibox/layout/fixed.lua

@@ -51,7 +51,7 @@ function fixed:layout(context, width, height)
 end
 
 --- Add some widgets to the given fixed layout
--- @tparam widget ... Widgets that should be added (must at least be one)
+-- @param ... Widgets that should be added (must at least be one)
 function fixed:add(...)
     -- No table.pack in Lua 5.1 :-(
     local args = { n=select('#', ...), ... }
@@ -63,6 +63,140 @@ function fixed:add(...)
     self:emit_signal("widget::layout_changed")
 end
 
+
+--- Remove a widget from the layout
+-- @tparam number index The widget index to remove
+-- @treturn boolean index If the operation is successful
+function fixed:remove(index)
+    if not index or index < 1 or index > #self.widgets then return false end
+
+    table.remove(self.widgets, index)
+
+    self:emit_signal("widget::layout_changed")
+
+    return true
+end
+
+--- Remove one or more widgets from the layout
+-- The last parameter can be a boolean, forcing a recursive seach of the
+-- widget(s) to remove.
+-- @param widget ... Widgets that should be removed (must at least be one)
+-- @treturn boolean If the operation is successful
+function fixed:remove_widgets(...)
+    local args = { ... }
+
+    local recursive = type(args[#args]) == "boolean" and args[#args]
+
+    local ret = true
+    for k, rem_widget in ipairs(args) do
+        if recursive and k == #args then break end
+
+        local idx, l = self:index(rem_widget, recursive)
+
+        if idx and l and l.remove then
+            l:remove(idx, false)
+        else
+            ret = false
+        end
+
+    end
+
+    return #args > (recursive and 1 or 0) and ret
+end
+
+--- Get all children of this layout
+-- @treturn table a list of all widgets
+function fixed:get_children()
+    return self.widgets
+end
+
+--- Replace the first instance of `widget` in the layout with `widget2`
+-- @param widget The widget to replace
+-- @param widget2 The widget to replace `widget` with
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+function fixed:replace_widget(widget, widget2, recursive)
+    local idx, l = self:index(widget, recursive)
+
+    if idx and l then
+        l:set(idx, widget2)
+        return true
+    end
+
+    return false
+end
+
+--- Swap 2 widgets in a layout
+-- @tparam number index1 The first widget index
+-- @tparam number index2 The second widget index
+-- @treturn boolean If the operation is successful
+function fixed:swap(index1, index2)
+    if not index1 or not index2 or index1 > #self.widgets
+        or index2 > #self.widgets then
+        return false
+    end
+
+    local widget1, widget2 = self.widgets[index1], self.widgets[index2]
+
+    self:set(index1, widget2)
+    self:set(index2, widget1)
+
+    return true
+end
+
+--- Swap 2 widgets in a layout
+-- If widget1 is present multiple time, only the first instance is swapped
+-- @param widget1 The first widget
+-- @param widget2 The second widget
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+function fixed:swap_widgets(widget1, widget2, recursive)
+    base.check_widget(widget1)
+    base.check_widget(widget2)
+
+    local idx1, l1 = self:index(widget1, recursive)
+    local idx2, l2 = self:index(widget2, recursive)
+
+    if idx1 and l1 and idx2 and l2 then
+        l1:set(idx1, widget2)
+        l2:set(idx2, widget1)
+
+        return true
+    end
+
+    return false
+end
+
+--- Set a widget at a specific index, replace the current one
+-- @tparam number index A widget or a widget index
+-- @param widget2 The widget to take the place of the first one
+-- @treturn boolean If the operation is successful
+function fixed:set(index, widget2)
+    if (not widget2) or (not self.widgets[index]) then return false end
+
+    base.check_widget(widget2)
+
+    self.widgets[index] = widget2
+
+    self:emit_signal("widget::layout_changed")
+
+    return true
+end
+
+--- Insert a new widget in the layout at position `index`
+-- @tparam number index The position
+-- @param widget The widget
+-- @treturn boolean If the operation is successful
+function fixed:insert(index, widget)
+    if not index or index < 1 or index > #self.widgets + 1 then return false end
+
+    base.check_widget(widget)
+    table.insert(self.widgets, index, widget)
+    self:emit_signal("widget::layout_changed")
+
+    return true
+end
+
 --- Fit the fixed layout into the given space
 -- @param context The context in which we are fit.
 -- @param orig_width The available width.

lib/wibox/layout/flex.lua

@@ -37,6 +37,27 @@ local flex = {}
 -- @name add
 -- @class function
 
+--- Set a widget at a specific index, replace the current one
+-- @tparam number index A widget or a widget index
+-- @param widget2 The widget to take the place of the first one
+-- @treturn boolean If the operation is successful
+-- @name set
+-- @class function
+
+--- Remove a widget from the layout
+-- @tparam index The widget index to remove
+-- @treturn boolean index If the operation is successful
+-- @name remove
+-- @class function
+
+--- Remove one or more widgets from the layout
+-- The last parameter can be a boolean, forcing a recursive seach of the
+-- widget(s) to remove.
+-- @param widget ... Widgets that should be removed (must at least be one)
+-- @treturn boolean If the operation is successful
+-- @name remove_widgets
+-- @class function
+
 --- Fit the fixed layout into the given space
 -- @param layout The layout you are modifying.
 -- @param context The context in which we are fit.
@@ -50,6 +71,37 @@ local flex = {}
 -- @name reset
 -- @class function
 
+--- Replace the first instance of `widget` in the layout with `widget2`
+-- @param widget The widget to replace
+-- @param widget2 The widget to replace `widget` with
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+-- @name replace_widget
+-- @class function
+
+--- Swap 2 widgets in a layout
+-- @tparam number index1 The first widget index
+-- @tparam number index2 The second widget index
+-- @treturn boolean If the operation is successful
+-- @name swap
+-- @class function
+
+--- Swap 2 widgets in a layout
+-- If widget1 is present multiple time, only the first instance is swapped
+-- @param widget1 The first widget
+-- @param widget2 The second widget
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+-- @name swap_widgets
+-- @class function
+
+--- Insert a new widget in the layout at position `index`
+-- @tparam number index The position
+-- @param widget The widget
+-- @treturn boolean If the operation is successful
+-- @name insert
+-- @class function
+
 --- Layout a flex layout. Each widget gets an equal share of the available space.
 -- @param context The context in which we are drawn.
 -- @param width The available width.