awesome/lib/wibox/layout/constraint.lua.in

142 lines
4.1 KiB
Lua

---------------------------------------------------------------------------
-- @author Lukáš Hrázký
-- @copyright 2012 Lukáš Hrázký
-- @release @AWESOME_VERSION@
---------------------------------------------------------------------------
local pairs = pairs
local type = type
local setmetatable = setmetatable
local base = require("wibox.layout.base")
local widget_base = require("wibox.widget.base")
local math = math
-- wibox.layout.constraint
local constraint = { mt = {} }
--- Draw a constraint layout
function constraint:draw(wibox, cr, width, height)
if not self.widget then
return
end
base.draw_widget(wibox, cr, self.widget, 0, 0, width, height)
end
--- Fit a constraint layout into the given space
function constraint:fit(width, height)
local w, h
if self.widget then
w = self._strategy(width, self._width)
h = self._strategy(height, self._height)
w, h = base.fit_widget(self.widget, w, h)
else
w, h = 0, 0
end
w = self._strategy(w, self._width)
h = self._strategy(h, self._height)
return w, h
end
--- Set the widget that this layout adds a constraint on.
function constraint:set_widget(widget)
if self.widget then
self.widget:disconnect_signal("widget::updated", self._emit_updated)
end
if widget then
widget_base.check_widget(widget)
widget:connect_signal("widget::updated", self._emit_updated)
end
self.widget = widget
self:emit_signal("widget::updated")
end
--- Set the strategy to use for the constraining. Valid values are 'max',
-- 'min' or 'exact'. Throws an error on invalid values.
function constraint:set_strategy(val)
local func = {
min = function(real_size, constraint)
return constraint and math.max(constraint, real_size) or real_size
end,
max = function(real_size, constraint)
return constraint and math.min(constraint, real_size) or real_size
end,
exact = function(real_size, constraint)
return constraint or real_size
end
}
if not func[val] then
error("Invalid strategy for constraint layout: " .. tostring(val))
end
self._strategy = func[val]
self:emit_signal("widget::updated")
end
--- Set the maximum width to val. nil for no width limit.
function constraint:set_width(val)
self._width = val
self:emit_signal("widget::updated")
end
--- Set the maximum height to val. nil for no height limit.
function constraint:set_height(val)
self._height = val
self:emit_signal("widget::updated")
end
--- Reset this layout. The widget will be unreferenced, strategy set to "max"
-- and the constraints set to nil.
function constraint:reset()
self._width = nil
self._height = nil
self:set_strategy("max")
self:set_widget(nil)
end
--- Returns a new constraint layout. This layout will constraint the size of a
-- widget according to the strategy. Note that this will only work for layouts
-- that respect the widget's size, eg. fixed layout. In layouts that don't
-- (fully) respect widget's requested size, the inner widget still might get
-- drawn with a size that does not fit the constraint, eg. in flex layout.
-- @param widget A widget to use (optional)
-- @param strategy How to constraint the size. 'max' (default), 'min' or
-- 'exact'. (optional)
-- @param width The maximum width of the widget. nil for no limit. (optional)
-- @param height The maximum height of the widget. nil for no limit. (optional)
local function new(widget, strategy, width, height)
local ret = widget_base.make_widget()
for k, v in pairs(constraint) do
if type(v) == "function" then
ret[k] = v
end
end
ret._emit_updated = function()
ret:emit_signal("widget::updated")
end
ret:set_strategy(strategy or "max")
ret:set_width(width)
ret:set_height(height)
if widget then
ret:set_widget(widget)
end
return ret
end
function constraint.mt:__call(...)
return new(...)
end
return setmetatable(constraint, constraint.mt)
-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80