Refactor: delete StackItem

Callers skip a hidden child with if !hidden { build() }; an unbuilt
child already takes no room and no gap. Docs, Example and Gallery
updated.

docs/components/005-stack.md

@@ -2,14 +2,16 @@
 
 ## 用途
 
-按横向或纵向排列子元素，统一间距、对齐与换行。用 `StackItem` 包裹可隐藏的子项，隐藏时不占位置也不留间距。
+按横向或纵向排列子元素，统一间距、对齐与换行。要隐藏子项就不构建它（`if !hidden { build() }`），未构建的子项不占位置也不留间距。
 
 ## 最小示例
 
 ```go
 mujica.Stack(c, mujica.StackOptions{Horizontal: true, Gap: mujica.SpaceM}, func() {
 	mujica.Button(c, "Save", mujica.ButtonOptions{})
-	mujica.StackItem(!showDraft, func() { mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary}) })
+	if showDraft {
+		mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary})
+	}
 	mujica.Button(c, "Cancel", mujica.ButtonOptions{Variant: mujica.Ghost})
 })
 ```
@@ -17,7 +19,6 @@ mujica.Stack(c, mujica.StackOptions{Horizontal: true, Gap: mujica.SpaceM}, func(
 签名：
 
 - `func Stack(c *ui.Context, opts StackOptions, children func()) *ui.Element`
-- `func StackItem(hidden bool, build func())`
 
 ## 参数
 
@@ -29,8 +30,6 @@ mujica.Stack(c, mujica.StackOptions{Horizontal: true, Gap: mujica.SpaceM}, func(
 | `Justify` | `ui.Align` | `ui.Start` | 主轴分布：Start、Center、End、SpaceBetween、SpaceAround、SpaceEvenly。 |
 | `Wrap` | `bool` | false | 横向换行；纵向时设置会 panic。 |
 
-`StackItem`：`hidden` 为 true 时不构建 `build`，因此既不占空间也不产生间距。`build` 为 nil 时 panic。
-
 ## 状态
 
 布局组件，无交互状态。

example_layout_test.go

@@ -61,7 +61,9 @@ func ExampleStack() {
 		mujica.Use(c, mujica.Settings{})
 		mujica.Stack(c, mujica.StackOptions{Horizontal: true, Gap: mujica.SpaceM}, func() {
 			mujica.Button(c, "Save", mujica.ButtonOptions{})
-			mujica.StackItem(!showDraft, func() { mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary}) })
+			if showDraft {
+				mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary})
+			}
 			mujica.Button(c, "Cancel", mujica.ButtonOptions{Variant: mujica.Ghost})
 		})
 	}

examples/gallery/pages_layout.go

@@ -245,7 +245,9 @@ func layoutContainerDemo(c *ui.Context, log func(string)) {
 
 const layoutStackCode = `mujica.Stack(c, mujica.StackOptions{Horizontal: true, Gap: mujica.SpaceM}, func() {
 	mujica.Button(c, "Save", mujica.ButtonOptions{})
-	mujica.StackItem(!showDraft, func() { mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary}) })
+	if showDraft {
+		mujica.Button(c, "Draft", mujica.ButtonOptions{Variant: mujica.Secondary})
+	}
 	mujica.Button(c, "Cancel", mujica.ButtonOptions{Variant: mujica.Ghost})
 })`
 
@@ -276,11 +278,9 @@ func layoutStackDemo(c *ui.Context, log func(string)) {
 			mujica.Stack(c, mujica.StackOptions{Horizontal: s.horizontal, Wrap: s.wrap, Gap: layoutSpace(s.gap),
 				Align: align, Justify: justifies[s.justify]}, func() {
 				for _, n := range []string{"Save", "Draft", "Publish", "Archive", "Cancel"} {
-					mujica.StackItem(s.hide && n == "Draft", func() {
-						if mujica.Button(c, n, mujica.ButtonOptions{Variant: mujica.Secondary}).Clicked() {
-							log(n + " clicked")
-						}
-					})
+					if (!s.hide || n != "Draft") && mujica.Button(c, n, mujica.ButtonOptions{Variant: mujica.Secondary}).Clicked() {
+						log(n + " clicked")
+					}
 				}
 			}).Grow(1).Padding(12)
 		})

stack.go

@@ -26,7 +26,7 @@ type StackOptions struct {
 	Wrap bool
 }
 
-// Stack arranges children in a row or column. Build children with StackItem to hide them without leaving a gap.
+// Stack arranges children in a row or column. A child not built takes no room and no gap.
 func Stack(c *ui.Context, opts StackOptions, children func()) *ui.Element {
 	if children == nil {
 		panic("mujica: Stack needs children")
@@ -57,13 +57,3 @@ func Stack(c *ui.Context, opts StackOptions, children func()) *ui.Element {
 	}
 	return e.Children(children)
 }
-
-// StackItem builds one child of a Stack unless hidden; a hidden item takes no room and no gap.
-func StackItem(hidden bool, build func()) {
-	if build == nil {
-		panic("mujica: StackItem needs build")
-	}
-	if !hidden {
-		build()
-	}
-}

stack_test.go

@@ -30,7 +30,9 @@ func TestStackHiddenItemTakesNoGap(t *testing.T) {
 			Use(c, Settings{})
 			Stack(c, StackOptions{Horizontal: true, Gap: SpaceL}, func() {
 				a = ui.Box(c).Size(30, 10).Bounds()
-				StackItem(hide, func() { ui.Box(c).Size(30, 10) })
+				if !hide {
+					ui.Box(c).Size(30, 10)
+				}
 				last = ui.Box(c).Size(30, 10).Bounds()
 			})
 		}, 300, 300).Frame()
@@ -105,7 +107,6 @@ func TestStackSnapshot(t *testing.T) {
 			})
 			Stack(c, StackOptions{Horizontal: true, Justify: ui.SpaceBetween}, func() {
 				chip("Start")
-				StackItem(true, func() { chip("Hidden") })
 				chip("Between")
 				chip("End")
 			})