From 6c8dc6a52b97e3eab59cecc90ba37eb5f8027563 Mon Sep 17 00:00:00 2001
From: PeaAshMeter <ivanyr44@gmail.com>
Date: Sun, 31 May 2026 06:00:53 +0300
Subject: [PATCH] enscapsulate SingleChildElement.child

---
 lib/simple_ui/core/builder.lua              | 23 ++++++++++++++-------
 lib/simple_ui/core/element.lua              |  1 -
 lib/simple_ui/core/single_child_element.lua | 15 +++++++-------
 lib/simple_ui/elements/center.lua           | 12 +++++------
 lib/simple_ui/elements/flex.lua             |  4 ++--
 lib/simple_ui/elements/padding.lua          | 10 ++++-----
 lib/simple_ui/elements/placeholder.lua      | 10 ++++-----
 lib/simple_ui/elements/screen_area.lua      |  8 +++----
 lib/simple_ui/elements/sized_box.lua        |  8 +++----
 lib/simple_ui/level/test.lua                | 19 ++++++++++++-----
 10 files changed, 64 insertions(+), 46 deletions(-)

diff --git a/lib/simple_ui/core/builder.lua b/lib/simple_ui/core/builder.lua
index f777fd9..643fd8b 100644
--- a/lib/simple_ui/core/builder.lua
+++ b/lib/simple_ui/core/builder.lua
@@ -51,22 +51,31 @@ function builder:_makeKey(element)
     return element.key
 end
 
+--- @param cur UIElement
 --- @private
 function builder:build_step(cur)
+    cur = cur --[[@as SingleChildElement | MultiChildElement]]
     if cur.build then
-        local orphan = cur:build()
-        local child = cur.child
-        child = orphan
+        cur = cur --[[@as SingleChildElement]]
+
+        local child = cur:build()
         if not child then return end
 
-        child._parent_ = cur
-        cur.child = child
+        -- local oldChild = cur._child_
+        -- if oldChild then
+        --     for key, value in pairs(oldChild) do
+        --         if (not Element[key]) then child[key] = value end
+        --     end
+        -- end
 
-        self:build_step(cur.child)
+        cur._child_ = child
+        child._parent_ = cur
+
+        self:build_step(cur._child_)
     elseif cur.children then
+        cur = cur --[[@as MultiChildElement]]
         for _, child in ipairs(cur.children) do
             child._parent_ = cur
-
             self:build_step(child)
         end
     end
diff --git a/lib/simple_ui/core/element.lua b/lib/simple_ui/core/element.lua
index 4c96a2e..98de443 100644
--- a/lib/simple_ui/core/element.lua
+++ b/lib/simple_ui/core/element.lua
@@ -8,7 +8,6 @@ local Vec3 = require "lib.utils.vec3"
 --- @field _constraints_ Constraints
 --- @field _offset_ Vec3 Положение левого верхнего угла элемента в локальных координатах {x, y}. Устанавливается родительским элементом.
 --- @field _size_ Vec3 Размеры элемента {x, y}
---- @field build? fun(self, ctx: UIElement): UIElement
 local element = {}
 element.__index = element
 element.type = "Element"
diff --git a/lib/simple_ui/core/single_child_element.lua b/lib/simple_ui/core/single_child_element.lua
index 962dbb4..f21c94f 100644
--- a/lib/simple_ui/core/single_child_element.lua
+++ b/lib/simple_ui/core/single_child_element.lua
@@ -3,10 +3,11 @@ local Constraints = require "lib.simple_ui.core.constraints"
 
 --- @class SingleChildElement : UIElement
 --- @field child? UIElement
+--- @field _child_? UIElement
 local element = setmetatable({}, require "lib.simple_ui.core.element")
 element.__index = element
 
---- дефолтное поведение -- просто возвращать своего ребенка
+--- дефолтное поведение -- просто возвращать переданного ребенка
 function element:build()
     return self.child
 end
@@ -15,20 +16,20 @@ function element:layout()
     --- передать ребенку ограничения
     --- получить назад размеры
     --- разместить ребенка
-    if not self.child then return end
-    self.child._constraints_ = Constraints(self._constraints_)
-    self.child:layout()
-    self.child._offset_ = Vec3 {}
+    if not self._child_ then return end
+    self._child_._constraints_ = Constraints(self._constraints_)
+    self._child_:layout()
+    self._child_._offset_ = Vec3 {}
 end
 
 function element:update(dt)
-    if self.child then self.child:update(dt) end
+    if self._child_ then self._child_:update(dt) end
 end
 
 function element:draw()
     love.graphics.push("transform")
     love.graphics.translate(self._offset_.x, self._offset_.y)
-    if self.child then self.child:draw() end
+    if self._child_ then self._child_:draw() end
     love.graphics.pop()
 end
 
diff --git a/lib/simple_ui/elements/center.lua b/lib/simple_ui/elements/center.lua
index 3f564a5..98c42ce 100644
--- a/lib/simple_ui/elements/center.lua
+++ b/lib/simple_ui/elements/center.lua
@@ -9,13 +9,13 @@ element.type = "Center"
 function element:layout()
     self._size_ = Vec3 { self._constraints_.maxWidth, self._constraints_.maxHeight }
 
-    if not self.child then return end
-    self.child._constraints_ = Constraints(self._constraints_)
-    self.child:layout()
+    if not self._child_ then return end
+    self._child_._constraints_ = Constraints(self._constraints_)
+    self._child_:layout()
 
-    self.child._offset_ = Vec3 {
-        (self._size_.x - self.child._size_.x) / 2,
-        (self._size_.y - self.child._size_.y) / 2,
+    self._child_._offset_ = Vec3 {
+        (self._size_.x - self._child_._size_.x) / 2,
+        (self._size_.y - self._child_._size_.y) / 2,
     }
 end
 
diff --git a/lib/simple_ui/elements/flex.lua b/lib/simple_ui/elements/flex.lua
index 0058143..c98cd09 100644
--- a/lib/simple_ui/elements/flex.lua
+++ b/lib/simple_ui/elements/flex.lua
@@ -31,7 +31,7 @@ function element:layout()
         end
         local shift = 0
         for _, child in ipairs(self.children) do
-            child._offset_ = Vec3 { self._offset_.x + start + shift, self._offset_.y }
+            child._offset_ = Vec3 { start + shift, 0 }
             shift = shift + child._size_.x
         end
 
@@ -57,7 +57,7 @@ function element:layout()
         end
         local shift = 0
         for _, child in ipairs(self.children) do
-            child._offset_ = Vec3 { self._offset_.x, self._offset_.y + start + shift }
+            child._offset_ = Vec3 { 0, start + shift }
             shift = shift + child._size_.y
         end
 
diff --git a/lib/simple_ui/elements/padding.lua b/lib/simple_ui/elements/padding.lua
index 9ced4ef..71ea048 100644
--- a/lib/simple_ui/elements/padding.lua
+++ b/lib/simple_ui/elements/padding.lua
@@ -19,17 +19,17 @@ element.bottom = 0
 ---
 --- as in https://api.flutter.dev/flutter/widgets/Padding-class.html
 function element:layout()
-    if not self.child then return end
+    if not self._child_ then return end
     local c = Constraints(self._constraints_)
     c.maxWidth = c.maxWidth - self.left - self.right
     c.maxHeight = c.maxHeight - self.top - self.bottom
     c.maxWidth = c.maxWidth > 0 and c.maxWidth or 0
     c.maxHeight = c.maxHeight > 0 and c.maxHeight or 0
-    self.child._constraints_ = c
+    self._child_._constraints_ = c
 
-    self.child:layout()
-    self._size_ = Vec3 { self.child._size_.x + self.left + self.right, self.child._size_.y + self.top + self.bottom }
-    self.child._offset_ = Vec3 { self.left, self.top }
+    self._child_:layout()
+    self._size_ = Vec3 { self._child_._size_.x + self.left + self.right, self._child_._size_.y + self.top + self.bottom }
+    self._child_._offset_ = Vec3 { self.left, self.top }
 end
 
 --- @return Padding
diff --git a/lib/simple_ui/elements/placeholder.lua b/lib/simple_ui/elements/placeholder.lua
index 2146165..c4b175d 100644
--- a/lib/simple_ui/elements/placeholder.lua
+++ b/lib/simple_ui/elements/placeholder.lua
@@ -9,17 +9,17 @@ element.type = "Placeholder"
 function element:layout()
     self._size_ = Vec3 { self._constraints_.maxWidth, self._constraints_.maxHeight }
 
-    if not self.child then return end
-    self.child._constraints_ = Constraints(self._constraints_)
-    self.child:layout()
+    if not self._child_ then return end
+    self._child_._constraints_ = Constraints(self._constraints_)
+    self._child_:layout()
 end
 
 function element:draw()
     love.graphics.rectangle("line", self._offset_.x, self._offset_.y, self._size_.x, self._size_.y)
     love.graphics.line(self._offset_.x, self._offset_.y, self._offset_.x + self._size_.x, self._offset_.y + self._size_
-    .y)
+        .y)
     love.graphics.line(self._offset_.x, self._offset_.y + self._size_.y, self._offset_.x + self._size_.x, self._offset_
-    .y)
+        .y)
 end
 
 --- @return Placeholder
diff --git a/lib/simple_ui/elements/screen_area.lua b/lib/simple_ui/elements/screen_area.lua
index bab3124..60a1dfb 100644
--- a/lib/simple_ui/elements/screen_area.lua
+++ b/lib/simple_ui/elements/screen_area.lua
@@ -14,10 +14,10 @@ function element:layout()
     }
     self._size_ = Vec3 { screenW, screenH }
 
-    if not self.child then return end
-    self.child._constraints_ = Constraints(self._constraints_)
-    self.child:layout()
-    self.child._offset_ = Vec3 {}
+    if not self._child_ then return end
+    self._child_._constraints_ = Constraints(self._constraints_)
+    self._child_:layout()
+    self._child_._offset_ = Vec3 {}
 end
 
 --- @return ScreenArea
diff --git a/lib/simple_ui/elements/sized_box.lua b/lib/simple_ui/elements/sized_box.lua
index 37444be..94dbd00 100644
--- a/lib/simple_ui/elements/sized_box.lua
+++ b/lib/simple_ui/elements/sized_box.lua
@@ -11,13 +11,13 @@ element.height = 0
 function element:layout()
     self._size_ = Vec3 { self.width, self.height }
 
-    if not self.child then return end
-    self.child._constraints_ = Constraints {
+    if not self._child_ then return end
+    self._child_._constraints_ = Constraints {
         maxWidth = self.width,
         maxHeight = self.height,
     }
-    self.child:layout()
-    self.child._offset_ = Vec3 {}
+    self._child_:layout()
+    self._child_._offset_ = Vec3 {}
 end
 
 --- @return SizedBox
diff --git a/lib/simple_ui/level/test.lua b/lib/simple_ui/level/test.lua
index c567e92..049b639 100644
--- a/lib/simple_ui/level/test.lua
+++ b/lib/simple_ui/level/test.lua
@@ -18,8 +18,8 @@ Canary.type = "Canary"
 
 local reported = false
 function Canary:build()
-    -- self.i = self.i and self.i + 1 or 0
-    -- print(self.i)
+    self.i = self.i and self.i + 1 or 0
+    print(self.i)
     -- if not reported then
     --     self:traverseUp(function(element)
     --         print(element.type)
@@ -60,7 +60,7 @@ function MyWidget:build()
                             width = 100,
                             height = 100,
                             child = Canary:new {
-                                i = 10
+                                i = 0
                             }
                         },
                     },
@@ -68,7 +68,7 @@ function MyWidget:build()
             },
             Flex:new {
                 key = "inner_flex2",
-                mainAxisAlignment = "center",
+                mainAxisAlignment = "end",
                 children = {
                     SizedBox:new {
                         width = 100,
@@ -84,6 +84,7 @@ function MyWidget:build()
                 },
 
             },
+            math.floor(love.timer.getTime()) % 2 == 0 and self.child or nil
         }
     }
 end
@@ -119,6 +120,14 @@ end
 
 return Builder {
     elementTree = ScreenArea:new {
-        child = MyWidget:new {}
+        child = MyWidget:new {
+            child = SizedBox:new {
+                width = 100,
+                height = 100,
+                child = Canary:new {
+                    i = 100
+                }
+            }
+        }
     }
 }