yui/layout.lua

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--- Layout container widget
--
-- Implements a layout widget
--
-- @classmod yui.Layout
-- @copyright 2022, The DoubleFourteen Code Forge
-- @author Lorenzo Cogotti, Andrea Pasquini
--
-- @{Layout} is an internal class, serving as a container of widgets and
-- defining their organization and display order.
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-- It is useful for arrangement customization.
local BASE = (...):gsub('layout$', '')
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local Widget = require(BASE..'widget')
local core = require(BASE..'core')
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local gear = require 'lib.gear'
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local isinstance = gear.meta.isinstance
local rectunion = gear.rect.union
local pointinrect = gear.rect.pointinside
local Layout = setmetatable({
__call = function(cls, args) return cls:new(args) end
}, Widget)
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Layout.__index = Layout
-- Calculate initial widget size.
local function calcsize(sizes, widget)
local w, h = widget.w, widget.h
if w == nil then
assert(#sizes > 0, "Default width is undefined!")
w = sizes[#sizes].w
end
if h == nil then
assert(#sizes > 0, "Default height is undefined!")
h = sizes[#sizes].h
end
if w == 'max' then
w = 0
for _,v in ipairs(sizes) do
if v.w > w then
w = v.w
end
end
elseif w == 'median' then
w = 0
for _,v in ipairs(sizes) do
w = w + v.w
end
w = math.ceil(w / #sizes)
elseif w == 'min' then
w = math.huge
for _,v in ipairs(sizes) do
if v.w < w then
w = v.w
end
end
else
assert(type(w) == 'number')
end
if h == 'max' then
h = 0
for _,v in ipairs(sizes) do
if v.h > h then
h = v.h
end
end
elseif h == 'median' then
h = 0
for _,v in ipairs(sizes) do
h = h + v.h
end
h = math.ceil(h / #sizes)
elseif h == 'min' then
h = math.huge
for _,v in ipairs(sizes) do
if v.h < h then
h = v.h
end
end
else
assert(type(h) == 'number')
end
sizes[#sizes+1] = { w = w, h = h }
widget.w, widget.h = w, h
return w, h
end
-- Lay down container widgets according to Layout type.
function Layout:layoutWidgets()
local nx,ny = self.x,self.y
local sizes = {}
local stack = self.stack
local pad = self.padding
-- Container bounds, empty
local rx,ry,rw,rh = nx,ny,-1,-1
-- Layout container children
for _,widget in ipairs(self) do
widget.x, widget.y = nx, ny
widget.ui = self.ui
widget.parent = self
if isinstance(widget, Layout) then
widget:layoutWidgets()
end
local w,h = calcsize(sizes, widget)
rx,ry,rw,rh = rectunion(rx,ry,rw,rh, nx,ny,w,h)
nx,ny = self.advance(nx,ny, w,h, pad)
stack[#stack+1] = widget
end
self.x = rx
self.y = ry
self.w = math.max(rw, 0)
self.h = math.max(rh, 0)
end
-- Find layout's child containing the provided widget.
local function childof(layout, widget)
local parent = widget.parent
while parent ~= layout do
widget = parent
parent = widget.parent
end
return widget
end
local function scanforward(layout, from)
from = from or 1
for i = from,#layout do
local w = layout[i]
if not w.nofocus then
return isinstance(w, Layout) and scanforward(w) or w
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end
end
end
local function scanbackwards(layout, from)
from = from or #layout
for i = from,1,-1 do
local w = layout[i]
if not w.nofocus then
return isinstance(w, Layout) and scanforward(w) or w
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end
end
end
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--- Attributes accepted by the Layout widget
--
-- @field padding (number) number of pixels between two elements
-- @table LayoutAttributes
--- Layout constructor
-- @param args (@{LayoutAttributes}) widget attributes
function Layout:new(args)
self = setmetatable(args, self)
self.padding = self.padding or 0
self.stack = {}
-- A Layout ignores focus if empty or containing only nofocus widgets
self.nofocus = true
for _,w in ipairs(self) do
if not w.nofocus then
self.nofocus = false
break
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end
end
return self
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end
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--- Find the first widget in the layout accepting focus.
function Layout:first()
return scanforward(self)
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end
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--- Find the last widget in the layout accepting focus.
function Layout:last()
return scanbackwards(self)
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end
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--- Find the next focusable widget after the provided one.
function Layout:after(widget)
widget = childof(self, widget)
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for i = 1,#self do
if self[i] == widget then
-- Search to the right/down
return scanforward(self, i+1)
end
end
end
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--- Find the previous focusable widget before the provided one.
function Layout:before(widget)
widget = childof(self, widget)
for i = 1,#self do
if self[i] == widget then
-- Search to the left/up
return scanbackwards(self, i-1)
end
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end
end
function Layout:onPointerInput(px,py, clicked, down)
local stack = self.stack
-- Propagate pointer event from topmost widget to bottom
for i = #stack,1,-1 do
local widget = stack[i]
local x,y,w,h = widget.x,widget.y,widget.w,widget.h
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if pointinrect(px,py, x,y,w,h) then
widget:onPointerInput(px,py, clicked, down)
break
end
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end
end
function Layout:update(dt)
for _,widget in ipairs(self.stack) do
widget:update(dt)
end
end
function Layout:draw()
-- Draw all children according to their order (topmost last)
for _,widget in ipairs(self.stack) do
widget:draw()
end
end
return Layout