[*] General code improvement.

* Rework navigation allowing direct management and triggering for grabkeyboard widgets.
* Navigation code now behaves better with deeply nested layouts.
* Allow widget hierarchies deeper than 2 (__call() is implemented for every Widget metatable).
* Make BASE locals more secure (match '<filename>$' in regexp)

button.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('button', '')
+local BASE = (...):gsub('button$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')

checkbox.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('checkbox', '')
+local BASE = (...):gsub('checkbox$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')

choice.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('choice', '')
+local BASE = (...):gsub('choice$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')
@@ -6,7 +6,9 @@ local core = require(BASE..'core')
 local shadowtext = require 'lib.gear.shadowtext'
 local T = require('lib.moonspeak').translate
 
-local Choice = setmetatable({}, Widget)
+local Choice = setmetatable({
+    __call = function(cls, args) return cls.new(args) end
+}, Widget)
 Choice.__index = Choice
 
 

columns.lua

@@ -1,21 +1,20 @@
-local BASE = (...):gsub('columns', '')
+local BASE = (...):gsub('columns$', '')
 
 local Layout = require(BASE..'layout')
 
-
 -- Advance position to next column,
 -- given current position, widget dimensions and padding.
 local function columnadvance(x,y, ww,wh, padding)
     return x + ww + padding, y
 end
 
-function Columns(args)
-    local self = Layout.new(args)
+local Columns = setmetatable({
+    advance = columnadvance,
+    __call = function(cls, args) return cls.new(args) end
+}, Layout)
+Columns.__index = Columns
 
-    self.advance = columnadvance
-    self.prev = 'left'
-    self.next = 'right'
-    return self
-end
+
+function Columns.new(args) return setmetatable(Layout.new(args), Columns) end
 
 return Columns

core.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('core', '')
+local BASE = (...):gsub('core$', '')
 
 local core = { theme = require(BASE..'theme') }
 core.__index = core

input.lua

@@ -1,12 +1,15 @@
-local BASE = (...):gsub('input', '')
+local BASE = (...):gsub('input$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')
 
 local utf8 = require 'utf8'
 
--- Grabs keyboard on focus
-local Input = setmetatable({ grabkeyboard = true }, Widget)
+-- NOTE: Input manages keyboard directly.
+local Input = setmetatable({
+    grabkeyboard = true,
+    __call = function(cls, args) return cls.new(args) end
+}, Widget)
 Input.__index = Input
 
 
@@ -28,6 +31,18 @@ function Input.new(args)
     return self
 end
 
+-- NOTE: Input steals keyboard input on focus.
+function Input:gainFocus()
+    love.keyboard.setTextInput(true, self.x,self.y,self.w,self.h)
+    love.keyboard.setKeyRepeat(true)
+end
+function Input:loseFocus()
+    if love.system.getOS() == 'Android' or love.system.getOS() == 'iOS' then
+        love.keyboard.setTextInput(false)
+    end
+    love.keyboard.setKeyRepeat(false)
+end
+
 function Input:onPointerInput(px,py, clicked)
     if clicked then
         self:grabFocus()
@@ -92,9 +107,12 @@ function Input:keyreleased(key)
             self.cursor = 1
         elseif key == 'end' then
             self.cursor = utf8.len(self.text)+1
-        elseif key == 'return' then
-            self:onChange(self.text)
-            self.cursor = 1
+        elseif key == 'up' or key == 'down' then
+            self.ui:navigate(key)
+        elseif key == 'tab' or key == 'return' then
+            self.ui:navigate('right')
+        elseif key == 'escape' then
+            self.ui:navigate('cancel')
         end
     end
 end

label.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('label', '')
+local BASE = (...):gsub('label$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')
@@ -7,7 +7,10 @@ local shadowtext = require 'lib.gear.shadowtext'
 local T = require('lib.moonspeak').translate
 
 -- Labels don't accept focus
-local Label = setmetatable({ nofocus = true }, Widget)
+local Label = setmetatable({
+    nofocus = true,
+    __call = function(cls, args) return cls.new(args) end
+}, Widget)
 Label.__index = Label
 
 

layout.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('layout', '')
+local BASE = (...):gsub('layout$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')
@@ -9,7 +9,9 @@ local isinstance = gear.meta.isinstance
 local rectunion = gear.rect.union
 local pointinrect = gear.rect.pointinside
 
-local Layout = setmetatable({}, Widget)
+local Layout = setmetatable({
+    __call = function(cls, args) return cls.new(args) end
+}, Widget)
 Layout.__index = Layout
 
 
@@ -113,21 +115,6 @@ function Layout:layoutWidgets()
     self.h = math.max(rh, 0)
 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
-
-        if pointinrect(px,py, x,y,w,h) then
-            widget:onPointerInput(px,py, clicked, down)
-            break
-        end
-    end
-end
-
 -- Find layout's child containing the provided widget.
 local function childof(layout, widget)
     local parent = widget.parent
@@ -137,98 +124,27 @@ local function childof(layout, widget)
     end
     return widget
 end
-local function findfirst(widget)
-    while isinstance(widget, Layout) do
-        -- Find first element accepting focus
-        for i = 1,#widget do
-            if not widget[i].nofocus then
-                widget = widget[i]
-                break
-            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
         end
     end
-    return widget
 end
-local function findnext(layout, widget)
-    local child = childof(layout, widget)
+local function scanbackwards(layout, from)
+    from = from or #layout
 
-    for i,w in ipairs(layout) do
-        if w == child then
-            -- Search to the right, wraparound to the left
-            for j = i+1,#layout do
-                if not layout[j].nofocus then
-                    return findfirst(layout[j])
-                end
-            end
-            for j = 1,i-1 do
-                if not layout[j].nofocus then
-                    return findfirst(layout[j])
-                end
-            end
+    for i = from,1,-1 do
+        local w = layout[i]
+
+        if not w.nofocus then
+            return isinstance(w, Layout) and scanforward(w) or w
         end
     end
-    return widget
-end
-local function findprev(layout, widget)
-    local child = childof(layout, widget)
-
-    for i,w in ipairs(layout) do
-        if w == child then
-            -- Search to the left, wraparound to the right
-            for j = i-1,1,-1 do
-                if not layout[j].nofocus then
-                    return findfirst(layout[j])
-                end
-            end
-            for j = #layout,i+1,-1 do
-                if not layout[j].nofocus then
-                    return findfirst(layout[j])
-                end
-            end
-        end
-    end
-    return widget
-end
-
-function Layout:firstFocusableWidget()
-    return findfirst(self)
-end
-function Layout:nextFocusableWidget()
-    return findnext(self, self.ui.focused)
-end
-function Layout:previousFocusableWidget()
-    return findprev(self, self.ui.focused)
-end
-
-function Layout:onActionInput(action)
-    local handled = false
-
-    if action[self.next] then
-        local n = self:nextFocusableWidget()
-
-        n:grabFocus()
-        handled = true
-    end
-    if action[self.prev] then
-        local p = self:previousFocusableWidget()
-
-        p:grabFocus()
-        handled = true
-    end
-    return handled
-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
 
 function Layout.new(args)
@@ -245,7 +161,70 @@ function Layout.new(args)
             break
         end
     end
+
     return self
 end
 
+--- Find first widget in layout accepting focus.
+function Layout:first()
+    return scanforward(self)
+end
+
+--- Find last widget in layout accepting focus.
+function Layout:last()
+    return scanbackwards(self)
+end
+
+--- Find next focusable widget after the provided one.
+function Layout:after(widget)
+    widget = childof(self, widget)
+
+    for i = 1,#self do
+        if self[i] == widget then
+            -- Search to the right/down
+            return scanforward(self, i+1)
+        end
+    end
+end
+
+--- Find 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
+    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
+
+        if pointinrect(px,py, x,y,w,h) then
+            widget:onPointerInput(px,py, clicked, down)
+            break
+        end
+    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

rows.lua

@@ -1,21 +1,20 @@
-local BASE = (...):gsub('rows', '')
+local BASE = (...):gsub('rows$', '')
 
 local Layout = require(BASE..'layout')
 
-
 -- Advance position to next row,
 -- given current position, widget dimensions and padding.
 local function rowadvance(x,y, ww,wh, padding)
     return x, y + wh + padding
 end
 
-function Rows(args)
-    local self = Layout.new(args)
+local Rows = setmetatable({
+    advance = rowadvance,
+    __call = function(cls, args) return cls.new(args) end
+}, Layout)
+Rows.__index = Rows
 
-    self.advance = rowadvance
-    self.prev = 'up'
-    self.next = 'down'
-    return self
-end
+
+function Rows.new(args) return setmetatable(Layout.new(args), Rows) end
 
 return Rows

slider.lua

@@ -1,4 +1,4 @@
-local BASE = (...):gsub('slider', '')
+local BASE = (...):gsub('slider$', '')
 
 local Widget = require(BASE..'widget')
 local core = require(BASE..'core')

spacer.lua

@@ -1,14 +1,15 @@
-local BASE = (...):gsub('spacer', '')
+local BASE = (...):gsub('spacer$', '')
 
 local Widget = require(BASE..'widget')
 
 -- Spacers don't accept focus
-local Spacer = setmetatable({ nofocus = true }, Widget)
+local Spacer = setmetatable({
+    nofocus = true,
+    __call = function(cls, args) return cls.new(args) end
+}, Widget)
 Spacer.__index = Spacer
 
 
-function Spacer.new(args)
-    return setmetatable(args, Spacer)
-end
+function Spacer.new(args) return setmetatable(args, Spacer) end
 
 return Spacer

ui.lua

@@ -2,6 +2,8 @@ local BASE = (...):gsub('ui$', '')
 
 local Widget = require(BASE..'widget')
 local Layout = require(BASE..'layout')
+local Columns = require(BASE..'columns')
+local Rows = require(BASE..'rows')
 
 local gear = require 'lib.gear'
 
@@ -50,24 +52,6 @@ local function resolveautofocus(widget)
     return firstfocus, cancelfocus
 end
 
-local function propagateaction(ui, action)
-    local focused = ui.focused
-    if focused.grabkeyboard then
-        -- A widget stealing input
-        -- explicitly consumes any action.
-        return true
-    end
-    while focused ~= nil do
-        if focused:onActionInput(action) then
-            return true  -- action consumed
-        end
-
-        focused = focused.parent
-    end
-
-    return false
-end
-
 function Ui.new(args)
     local self = setmetatable(args, Ui)
     assert(#self == 1, "Ui.new() must have exactly one root widget.")
@@ -98,7 +82,7 @@ function Ui.new(args)
     local firstfocus, cancelfocus = resolveautofocus(root)
     if firstfocus == nil then
         firstfocus = isinstance(root, Layout) and
-                     root:firstFocusableWidget() or
+                     root:first() or
                      root
     end
 
@@ -138,28 +122,136 @@ function Ui:textedited(text, start, length)
     end
 end
 
-function Ui:update(dt)
-    local root = self[1]
-    local x,y,w,h = root.x,root.y,root.w,root.h
-    local snap = self.device:snapshot()
+local function actionpropagate(widget, action)
+    while widget ~= nil do
+        if widget:onActionInput(action) then
+            return true  -- action consumed
+        end
 
-    self.timer:update(dt)
+        widget = widget.parent
+    end
+
+    return false
+end
+
+local navs = { 'cancel', 'up', 'down', 'left', 'right' }
+
+local function globalactions(ui, snap)
+    for _,nav in ipairs(navs) do
+        if snap[nav] then
+            ui:navigate(nav)
+            break  -- discard other directions, if any
+        end
+    end
+end
+
+local function eventpropagate(ui, snap)
+    -- 1. Pointer events
+    if snap.pointer and not ui.grabpointer then
+        local root = ui[1]
+        local x,y,w,h = root.x,root.y,root.w,root.h
 
-    -- Propagate pointer events in focus order
-    if self.pointerActive then
         if snap.pointer and pointinrect(snap.px,snap.py, x,y,w,h) then
             root:onPointerInput(snap.px,snap.py, snap.clicked, snap.pointing)
         end
     end
 
-    -- Propagate actions from focused widget up
-    if snap.action and not propagateaction(self, snap) then
-        -- Take global actions if nobody consumed the event
-        if snap.cancel and self.cancelfocus then
-            -- Focus on the last widget with 'cancelfocus'
-            self.cancelfocus:grabFocus()
+    -- 2. Actions (keyboard/buttons)
+    if snap.action and not ui.grabkeyboard then
+        local consumed = actionpropagate(ui.focused, snap)
+
+        if not consumed then
+            -- 3. If no widget consumed action,
+            --    take global actions (e.g. navigation).
+            globalactions(ui, snap)
         end
     end
+end
+
+-- cls may be Rows, Columns or Layout in general
+local function containerof(widget, cls)
+    repeat
+        widget = widget.parent
+        if isinstance(widget, cls) then
+            return widget
+        end
+    until widget == nil
+end
+
+local function findprev(ui, cls, widget)
+    local child = widget
+
+    while true do
+        local container = containerof(child, cls)
+        if container == nil then
+            -- All the way up, either return the original
+            -- widget or wraparound to the bottom
+            return isinstance(child, cls) and child:last() or widget
+        end
+
+        local w = container:before(child)
+        if w ~= nil then
+            return w
+        end
+
+        child = container  -- move up into the hierarchy
+    end
+end
+
+-- Specular to findprev()
+local function findnext(ui, cls, widget)
+    local child = widget
+
+    while true do
+        local container = containerof(child, cls)
+        if container == nil then
+            return isinstance(child, cls) and child:first() or widget
+        end
+
+        local w = container:after(child)
+        if w ~= nil then
+            return w
+        end
+
+        child = container
+    end
+end
+
+--- Move focus to the given direction.
+--
+-- @param where (string) Direction to move to,
+--                       one of: 'up', 'down', 'left', 'right', 'cancel'.
+function Ui:navigate(where)
+    local nextfocus = nil
+
+    if where == 'cancel' then
+        nextfocus = self.cancelfocus
+    elseif where == 'up' then
+        nextfocus = findprev(self, Rows, self.focused)
+    elseif where == 'down' then
+        nextfocus = findnext(self, Rows, self.focused)
+    elseif where == 'left' then
+        nextfocus = findprev(self, Columns, self.focused)
+    elseif where == 'right' then
+        nextfocus = findnext(self, Columns, self.focused)
+    else
+        error("Bad direction: "..tostring(where))
+    end
+
+    if nextfocus ~= nil then
+        nextfocus:grabFocus()
+    end
+end
+
+function Ui:update(dt)
+    local root = self[1]
+    local snap = self.device:snapshot()
+
+    -- Update timer related effects
+    self.timer:update(dt)
+
+    -- Regular event propagation
+    eventpropagate(self, snap)
 
     -- Perform regular lifetime updates
     root:update(dt)

widget.lua

@@ -1,9 +1,7 @@
 local rectunion = require('lib.gear.rect').union
 
 local Widget = {
-    __call = function(cls, args)
-        return cls.new(args)
-    end
+    __call = function(cls, args) return cls.new(args) end
 }
 Widget.__index = Widget
 
@@ -40,25 +38,26 @@ function Widget:grabFocus()
     if focused ~= nil then
         -- Notify leave
         focused.hovered = false
-        if focused.grabkeyboard then
-            if love.system.getOS() == 'Android' or love.system.getOS() == 'iOS' then
-                love.keyboard.setTextInput(false)
-            end
-            love.keyboard.setKeyRepeat(false)
-        end
-
+        -- Widget specific focus loss
+        focused:loseFocus()
+        -- Event handler
         focused:onLeave()
+
+        if focused.grabkeyboard then
+            -- If focused widget stole input,
+            -- then drop current input snapshot, since
+            -- those events should have been already
+            -- managed directly
+            ui.device:snapshot()
+        end
     end
 
     local wasHovered = self.hovered
 
     self.hovered = true
-    if self.grabkeyboard then
-        love.keyboard.setTextInput(true, self.x,self.y,self.w,self.h)
-        love.keyboard.setKeyRepeat(true)
-    end
     if not wasHovered then
         -- First time hovered, notify enter
+        self:gainFocus()
         self:onEnter()
     end
 
@@ -100,7 +99,11 @@ function Widget:colorForState()
     end
 end
 
--- Common NOP event handlers
+-- NOP hooks for UI internal use
+function Widget:loseFocus() end
+function Widget:gainFocus() end
+
+-- NOP event handlers, publicly overridable
 function Widget:onHit() end
 function Widget:onEnter() end
 function Widget:onLeave() end