feat(window): add fill-center title bar policy and BasicTitleBar APIs

decorated-window-core/src/main/kotlin/io/github/kdroidfilter/nucleus/window/DialogTitleBarImpl.kt

@@ -17,6 +17,7 @@ fun DecoratedDialogScope.DialogTitleBarImpl(
     gradientStartColor: Color = Color.Unspecified,
     style: TitleBarStyle = LocalTitleBarStyle.current,
     controlButtonsDirection: LayoutDirection = LocalLayoutDirection.current,
+    layoutPolicy: TitleBarLayoutPolicy = TitleBarLayoutPolicy.Default,
     applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
     onPlace: (() -> Unit)? = null,
     backgroundContent: @Composable () -> Unit = {},
@@ -30,10 +31,36 @@ fun DecoratedDialogScope.DialogTitleBarImpl(
         gradientStartColor = gradientStartColor,
         style = style,
         controlButtonsDirection = controlButtonsDirection,
+        layoutPolicy = layoutPolicy,
         applyTitleBar = applyTitleBar,
         onPlace = onPlace,
         backgroundContent = backgroundContent,
     ) { _ ->
         content(dialogState)
     }
 }
+
+@Suppress("FunctionNaming", "LongParameterList")
+@Composable
+fun DecoratedDialogScope.DialogTitleBarImpl(
+    modifier: Modifier = Modifier,
+    gradientStartColor: Color = Color.Unspecified,
+    style: TitleBarStyle = LocalTitleBarStyle.current,
+    controlButtonsDirection: LayoutDirection = LocalLayoutDirection.current,
+    applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
+    onPlace: (() -> Unit)? = null,
+    backgroundContent: @Composable () -> Unit = {},
+    content: @Composable TitleBarScope.(DecoratedDialogState) -> Unit,
+) {
+    DialogTitleBarImpl(
+        modifier = modifier,
+        gradientStartColor = gradientStartColor,
+        style = style,
+        controlButtonsDirection = controlButtonsDirection,
+        layoutPolicy = TitleBarLayoutPolicy.Default,
+        applyTitleBar = applyTitleBar,
+        onPlace = onPlace,
+        backgroundContent = backgroundContent,
+        content = content,
+    )
+}

decorated-window-core/src/main/kotlin/io/github/kdroidfilter/nucleus/window/TitleBarCore.kt

@@ -24,30 +24,23 @@ import androidx.compose.ui.input.pointer.PointerEventPass
 import androidx.compose.ui.input.pointer.PointerEventType
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.layout.Layout
-import androidx.compose.ui.layout.Measurable
-import androidx.compose.ui.layout.MeasurePolicy
-import androidx.compose.ui.layout.MeasureResult
-import androidx.compose.ui.layout.MeasureScope
-import androidx.compose.ui.layout.Placeable
 import androidx.compose.ui.layout.layoutId
+import androidx.compose.ui.layout.onPlaced
 import androidx.compose.ui.layout.onSizeChanged
 import androidx.compose.ui.node.ModifierNodeElement
 import androidx.compose.ui.node.ParentDataModifierNode
 import androidx.compose.ui.platform.InspectorInfo
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.LocalLayoutDirection
-import androidx.compose.ui.unit.Constraints
 import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.LayoutDirection
-import androidx.compose.ui.unit.offset
 import io.github.kdroidfilter.nucleus.core.runtime.Platform
 import io.github.kdroidfilter.nucleus.window.styling.LocalTitleBarStyle
 import io.github.kdroidfilter.nucleus.window.styling.TitleBarStyle
 import kotlinx.coroutines.currentCoroutineContext
 import kotlinx.coroutines.isActive
 import java.awt.Window
-import kotlin.math.max
 
 private const val GRADIENT_MIDPOINT = 0.5f
 
@@ -70,6 +63,7 @@ fun GenericTitleBarImpl(
     gradientStartColor: Color = Color.Unspecified,
     style: TitleBarStyle = LocalTitleBarStyle.current,
     controlButtonsDirection: LayoutDirection = LocalLayoutDirection.current,
+    layoutPolicy: TitleBarLayoutPolicy = TitleBarLayoutPolicy.Default,
     applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
     onPlace: (() -> Unit)? = null,
     backgroundContent: @Composable () -> Unit = {},
@@ -128,16 +122,24 @@ fun GenericTitleBarImpl(
                     scope.content(state)
                 }
             },
-            modifier = Modifier.fillMaxSize(),
+            modifier = Modifier.fillMaxSize().onPlaced { onPlace?.invoke() },
             measurePolicy =
-                rememberTitleBarMeasurePolicy(window, state, applyTitleBar, controlButtonsDirection, onPlace),
+                rememberTitleBarMeasurePolicy(
+                    window = window,
+                    state = state,
+                    applyTitleBar = applyTitleBar,
+                    controlButtonsDirection = controlButtonsDirection,
+                    layoutPolicy = layoutPolicy,
+                ),
         )
     }
 }
 
-@Suppress("FunctionNaming")
+@Suppress("FunctionNaming", "LongParameterList")
 @Composable
-fun DecoratedWindowScope.TitleBarImpl(
+fun GenericTitleBarImpl(
+    window: Window,
+    state: DecoratedWindowState,
     modifier: Modifier = Modifier,
     gradientStartColor: Color = Color.Unspecified,
     style: TitleBarStyle = LocalTitleBarStyle.current,
@@ -154,147 +156,66 @@ fun DecoratedWindowScope.TitleBarImpl(
         gradientStartColor = gradientStartColor,
         style = style,
         controlButtonsDirection = controlButtonsDirection,
+        layoutPolicy = TitleBarLayoutPolicy.Default,
         applyTitleBar = applyTitleBar,
         onPlace = onPlace,
         backgroundContent = backgroundContent,
         content = content,
     )
 }
 
-class TitleBarMeasurePolicy(
-    private val window: Window,
-    private val state: DecoratedWindowState,
-    private val applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
-    private val controlButtonsDirection: LayoutDirection,
-    private val onPlace: (() -> Unit)? = null,
-) : MeasurePolicy {
-    @Suppress("CyclomaticComplexMethod", "LongMethod")
-    override fun MeasureScope.measure(
-        measurables: List<Measurable>,
-        constraints: Constraints,
-    ): MeasureResult {
-        if (measurables.isEmpty()) {
-            return layout(width = constraints.minWidth, height = constraints.minHeight) {}
-        }
-
-        var maxSpaceVertically = constraints.minHeight
-        val contentConstraints = constraints.copy(minWidth = 0, minHeight = 0)
-
-        // Two-pass measurement: End items are measured independently so they
-        // don't reduce the available width for Start/Center items.  This keeps
-        // behaviour consistent with JBR where native caption buttons reserve
-        // space via padding insets rather than Compose item measurement.
-        val endMeasurables = mutableListOf<Pair<Measurable, Placeable>>()
-        val otherMeasurables = mutableListOf<Pair<Measurable, Placeable>>()
-
-        // Pass 1 – measure End-aligned items among themselves
-        var endOccupied = 0
-        for (it in measurables) {
-            val alignment = (it.parentData as? TitleBarChildDataNode)?.horizontalAlignment
-            if (alignment != Alignment.End) continue
-            val placeable = it.measure(contentConstraints.offset(horizontal = -endOccupied))
-            endOccupied += placeable.width
-            maxSpaceVertically = max(maxSpaceVertically, placeable.height)
-            endMeasurables += it to placeable
-        }
-
-        // Pass 2 – measure non-End items with full available width
-        var otherOccupied = 0
-        @Suppress("LoopWithTooManyJumpStatements")
-        for (it in measurables) {
-            val alignment = (it.parentData as? TitleBarChildDataNode)?.horizontalAlignment
-            if (alignment == Alignment.End) continue
-            val placeable = it.measure(contentConstraints.offset(horizontal = -otherOccupied))
-            if (constraints.maxWidth < otherOccupied + placeable.width) break
-            otherOccupied += placeable.width
-            maxSpaceVertically = max(maxSpaceVertically, placeable.height)
-            otherMeasurables += it to placeable
-        }
-
-        val measuredPlaceable = endMeasurables + otherMeasurables
-        val boxHeight = maxSpaceVertically
-
-        val contentPadding = applyTitleBar(boxHeight.toDp(), state)
-
-        // Use Ltr to get absolute left/right insets.
-        val leftInset = contentPadding.calculateLeftPadding(LayoutDirection.Ltr).roundToPx()
-        val rightInset = contentPadding.calculateRightPadding(LayoutDirection.Ltr).roundToPx()
-
-        val occupiedSpaceHorizontally = endOccupied + otherOccupied + leftInset + rightInset
-        val boxWidth = maxOf(constraints.minWidth, occupiedSpaceHorizontally)
-
-        return layout(boxWidth, boxHeight) {
-            onPlace?.invoke()
-
-            val placeableGroups =
-                measuredPlaceable.groupBy { (measurable, _) ->
-                    (measurable.parentData as? TitleBarChildDataNode)?.horizontalAlignment
-                        ?: Alignment.CenterHorizontally
-                }
-
-            val contentIsRtl = layoutDirection == LayoutDirection.Rtl
-            val controlsOnRight = controlButtonsDirection == LayoutDirection.Ltr
-
-            // Absolute occupied-space tracking for each side
-            var leftUsed = leftInset
-            var rightUsed = rightInset
-
-            // End items (control buttons) first — they claim the extreme edge
-            // before Start items, so they always stay at their designated side
-            // even when content and controls share the same edge.
-            placeableGroups[Alignment.End]?.forEach { (_, placeable) ->
-                val y = Alignment.CenterVertically.align(placeable.height, boxHeight)
-                if (controlsOnRight) {
-                    placeable.place(boxWidth - rightUsed - placeable.width, y)
-                    rightUsed += placeable.width
-                } else {
-                    placeable.place(leftUsed, y)
-                    leftUsed += placeable.width
-                }
-            }
-
-            // Start items: leading edge of the content direction
-            placeableGroups[Alignment.Start]?.forEach { (_, placeable) ->
-                val y = Alignment.CenterVertically.align(placeable.height, boxHeight)
-                if (contentIsRtl) {
-                    placeable.place(boxWidth - rightUsed - placeable.width, y)
-                    rightUsed += placeable.width
-                } else {
-                    placeable.place(leftUsed, y)
-                    leftUsed += placeable.width
-                }
-            }
-
-            // Center items: clamped between occupied edges
-            val centerPlaceable = placeableGroups[Alignment.CenterHorizontally].orEmpty()
-            val requiredCenterSpace = centerPlaceable.sumOf { it.second.width }
-            val minX = leftUsed
-            val maxX = boxWidth - rightUsed - requiredCenterSpace
-            var centerX = (boxWidth - requiredCenterSpace) / 2
-
-            if (minX <= maxX) {
-                centerX = centerX.coerceIn(minX, maxX)
-                centerPlaceable.forEach { (_, placeable) ->
-                    val y = Alignment.CenterVertically.align(placeable.height, boxHeight)
-                    placeable.place(centerX, y)
-                    centerX += placeable.width
-                }
-            }
-        }
-    }
+@Suppress("FunctionNaming")
+@Composable
+fun DecoratedWindowScope.TitleBarImpl(
+    modifier: Modifier = Modifier,
+    gradientStartColor: Color = Color.Unspecified,
+    style: TitleBarStyle = LocalTitleBarStyle.current,
+    controlButtonsDirection: LayoutDirection = LocalLayoutDirection.current,
+    layoutPolicy: TitleBarLayoutPolicy = TitleBarLayoutPolicy.Default,
+    applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
+    onPlace: (() -> Unit)? = null,
+    backgroundContent: @Composable () -> Unit = {},
+    content: @Composable TitleBarScope.(DecoratedWindowState) -> Unit,
+) {
+    GenericTitleBarImpl(
+        window = window,
+        state = state,
+        modifier = modifier,
+        gradientStartColor = gradientStartColor,
+        style = style,
+        controlButtonsDirection = controlButtonsDirection,
+        layoutPolicy = layoutPolicy,
+        applyTitleBar = applyTitleBar,
+        onPlace = onPlace,
+        backgroundContent = backgroundContent,
+        content = content,
+    )
 }
 
+@Suppress("FunctionNaming")
 @Composable
-fun rememberTitleBarMeasurePolicy(
-    window: Window,
-    state: DecoratedWindowState,
-    applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
+fun DecoratedWindowScope.TitleBarImpl(
+    modifier: Modifier = Modifier,
+    gradientStartColor: Color = Color.Unspecified,
+    style: TitleBarStyle = LocalTitleBarStyle.current,
     controlButtonsDirection: LayoutDirection = LocalLayoutDirection.current,
+    applyTitleBar: (Dp, DecoratedWindowState) -> PaddingValues,
     onPlace: (() -> Unit)? = null,
-): MeasurePolicy =
-    remember(window, state, applyTitleBar, controlButtonsDirection, onPlace) {
-        TitleBarMeasurePolicy(window, state, applyTitleBar, controlButtonsDirection, onPlace)
-    }
+    backgroundContent: @Composable () -> Unit = {},
+    content: @Composable TitleBarScope.(DecoratedWindowState) -> Unit,
+) {
+    TitleBarImpl(
+        modifier = modifier,
+        gradientStartColor = gradientStartColor,
+        style = style,
+        controlButtonsDirection = controlButtonsDirection,
+        layoutPolicy = TitleBarLayoutPolicy.Default,
+        applyTitleBar = applyTitleBar,
+        onPlace = onPlace,
+        backgroundContent = backgroundContent,
+        content = content,
+    )
+}
 
 @Stable
 interface TitleBarScope {
@@ -309,7 +230,7 @@ interface TitleBarScope {
      * fullscreen on non-notch screens.
      *
      * Standard [clickable][androidx.compose.foundation.clickable] requires a
-     * complete Press → Release (tap) gesture. On some JDK/macOS combinations,
+     * complete Press -> Release (tap) gesture. On some JDK/macOS combinations,
      * the system injects phantom pointer-exit events between Press and Release
      * in fullscreen, which cancels the tap gesture and prevents `onClick` from
      * firing.