add padding widget

lib/ui/core.lua

@@ -471,6 +471,62 @@ local function mk_ctor(class)
     return class
 end
 
+-- =============== Padding (single child) ===============
+
+---@class Padding: SingleChildElement
+---@field padding {left?: number, right?: number, top?: number, bottom?: number}
+local Padding = setmetatable({}, { __index = SingleChildElement })
+Padding.__index = Padding
+
+---@param props { padding?: {left?: number, right?: number, top?: number, bottom?: number}, child?: Element }|nil
+---@return Padding
+function Padding:new(props)
+    local o = SingleChildElement.new(self, props)
+    ---@cast o Padding
+    local p = o.padding or {}
+    o.padding = {
+        left   = tonumber(p.left) or 0,
+        right  = tonumber(p.right) or 0,
+        top    = tonumber(p.top) or 0,
+        bottom = tonumber(p.bottom) or 0,
+    }
+    return o
+end
+
+function Padding:layout(constraints)
+    local L = self.padding.left
+    local R = self.padding.right
+    local T = self.padding.top
+    local B = self.padding.bottom
+    local hp = L + R
+    local vp = T + B
+
+    -- Вычитаем паддинги из ограничений для ребёнка
+    local child_min_w = math.max(0, constraints.min_w - hp)
+    local child_min_h = math.max(0, constraints.min_h - vp)
+    local child_max_w = math.max(0, constraints.max_w - hp)
+    local child_max_h = math.max(0, constraints.max_h - vp)
+    local child_c = make_constraints(child_min_w, child_min_h, child_max_w, child_max_h)
+
+    if self.child then
+        self.child:layout(child_c)
+        local w = self.child.size.x + hp
+        local h = self.child.size.y + vp
+        self.size.x, self.size.y = clamp_size(w, h, constraints)
+    else
+        -- Нет ребёнка: размер равен сумме паддингов (с учётом ограничений)
+        self.size.x, self.size.y = clamp_size(hp, vp, constraints)
+    end
+end
+
+function Padding:arrange(origin)
+    self.origin = Vec3 { origin.x, origin.y, origin.z or 0 }
+    if not self.child then return end
+    local L = self.padding.left
+    local T = self.padding.top
+    self.child:arrange(Vec3 { self.origin.x + L, self.origin.y + T, self.origin.z })
+end
+
 ui.Element     = Element
 ui.Root        = mk_ctor(Root)
 ui.Align       = mk_ctor(Align)
@@ -478,6 +534,7 @@ ui.Row         = mk_ctor(Row)
 ui.Column      = mk_ctor(Column)
 ui.Rectangle   = mk_ctor(Rectangle)
 ui.Expanded    = mk_ctor(Expanded)
+ui.Padding     = mk_ctor(Padding)
 
 -- Экспорт вспомогательных, если пригодится
 ui.constraints = {

main.lua

@@ -33,7 +33,7 @@ function love.load()
                         children = {
                             ui.Rectangle { size = Vec3 { 100, 100 }, color = { 0, 0, 1 } },
                             ui.Rectangle { size = Vec3 { 200, 100 }, color = { 1, 0, 0 } },
-                            ui.Expanded { flex = 1, child = ui.Rectangle { size = Vec3 { 100, 150 }, color = { 0, 1, 0 } } },
+                            ui.Padding { padding = { left = 10, right = 10 }, child = ui.Rectangle { size = Vec3 { 100, 150 }, color = { 0, 1, 0 } } },
                             ui.Rectangle { size = Vec3 { 100, 100 }, color = { 1, 1, 0 } },
                         }
                     },