Move LayoutAllocators to the layouts package

core/shared/src/main/scala/eu/joaocosta/interim/LayoutAllocator.scala

@@ -0,0 +1,28 @@
+package eu.joaocosta.interim
+
+import eu.joaocosta.interim.{Font, HorizontalAlignment, Rect, TextLayout, VerticalAlignment}
+
+/** A layout allocator is a side-effectful function that, given a size (width or height) tries to allocate
+  * a new area.
+  *
+  * Note that calls to this function are side effectful, as each call reserves an area.
+  */
+trait LayoutAllocator:
+  def area: Rect
+
+  def allocate(width: Int, height: Int): Rect
+  def allocate(text: String, font: Font, paddingW: Int = 0, paddingH: Int = 0): Rect =
+    val textArea =
+      TextLayout.computeArea(area.resize(-2 * paddingW, -2 * paddingH), text, font)
+    allocate(textArea.w + 2 * paddingW, textArea.h + 2 * paddingH)
+
+  def fill(): Rect = allocate(Int.MaxValue, Int.MaxValue)
+
+object LayoutAllocator:
+  trait RowAllocator extends LayoutAllocator:
+    def nextRow(height: Int): Rect
+    def allocate(width: Int, height: Int): Rect = nextRow(height)
+
+  trait ColumnAllocator extends LayoutAllocator:
+    def nextColumn(width: Int): Rect
+    def allocate(width: Int, height: Int): Rect = nextColumn(width)

core/shared/src/main/scala/eu/joaocosta/interim/api/Layouts.scala

@@ -1,7 +1,7 @@
 package eu.joaocosta.interim.api
 
-import eu.joaocosta.interim.api.LayoutAllocator._
-import eu.joaocosta.interim.{HorizontalAlignment, InputState, Rect, UiContext, VerticalAlignment}
+import eu.joaocosta.interim._
+import eu.joaocosta.interim.layouts._
 
 /** Objects containing all default layouts.
   *
@@ -75,7 +75,7 @@ trait Layouts:
       padding: Int,
       alignment: VerticalAlignment.Top.type | VerticalAlignment.Bottom.type = VerticalAlignment.Top
   )(body: DynamicRowAllocator ?=> T): T =
-    val allocator = new LayoutAllocator.DynamicRowAllocator(area, padding, alignment)
+    val allocator = new DynamicRowAllocator(area, padding, alignment)
     body(using allocator)
 
   /** Lays out the components in a sequence of columns of different sizes, separated by a padding.
@@ -88,7 +88,7 @@ trait Layouts:
       padding: Int,
       alignment: HorizontalAlignment.Left.type | HorizontalAlignment.Right.type = HorizontalAlignment.Left
   )(body: DynamicColumnAllocator ?=> T): T =
-    val allocator = new LayoutAllocator.DynamicColumnAllocator(area, padding, alignment)
+    val allocator = new DynamicColumnAllocator(area, padding, alignment)
     body(using allocator)
 
   /** Handle mouse events inside a specified area.

core/shared/src/main/scala/eu/joaocosta/interim/api/Primitives.scala

@@ -1,6 +1,6 @@
 package eu.joaocosta.interim.api
 
-import eu.joaocosta.interim.{Color, Font, HorizontalAlignment, Rect, RenderOp, UiContext, VerticalAlignment}
+import eu.joaocosta.interim._
 
 /** Object containing the default primitives.
   *

core/shared/src/main/scala/eu/joaocosta/interim/layouts/DynamicColumnAllocator.scala

@@ -0,0 +1,35 @@
+package eu.joaocosta.interim.layouts
+
+import eu.joaocosta.interim._
+
+final class DynamicColumnAllocator(
+    val area: Rect,
+    padding: Int,
+    alignment: HorizontalAlignment.Left.type | HorizontalAlignment.Right.type
+) extends LayoutAllocator.ColumnAllocator
+    with (Int => Rect):
+  private var currentX = area.x
+  private var currentW = area.w
+  private val dirMod   = if (alignment == HorizontalAlignment.Left) 1 else -1
+
+  def nextColumn(width: Int): Rect =
+    val absWidth = math.abs(width).toInt
+    if (absWidth == 0 || currentW <= 0) // Empty
+      area.copy(x = currentX, w = 0)
+    else if (absWidth >= currentW) // Fill remaining area
+      val areaX = currentX
+      val areaW = currentW
+      currentX = area.w
+      currentW = 0
+      area.copy(x = areaX, w = areaW)
+    else if (dirMod * width >= 0) // Fill from the left
+      val areaX = currentX
+      currentX += absWidth + padding
+      currentW -= absWidth + padding
+      area.copy(x = areaX, w = absWidth)
+    else // Fill from the right
+      val areaX = currentX + currentW - absWidth
+      currentW -= absWidth + padding
+      area.copy(x = areaX, w = absWidth)
+
+  def apply(height: Int) = nextColumn(height)

core/shared/src/main/scala/eu/joaocosta/interim/layouts/DynamicRowAllocator.scala

@@ -0,0 +1,35 @@
+package eu.joaocosta.interim.layouts
+
+import eu.joaocosta.interim._
+
+final class DynamicRowAllocator(
+    val area: Rect,
+    padding: Int,
+    alignment: VerticalAlignment.Top.type | VerticalAlignment.Bottom.type
+) extends LayoutAllocator.RowAllocator
+    with (Int => Rect):
+  private var currentY = area.y
+  private var currentH = area.h
+  private val dirMod   = if (alignment == VerticalAlignment.Top) 1 else -1
+
+  def nextRow(height: Int) =
+    val absHeight = math.abs(height).toInt
+    if (absHeight == 0 || currentH <= 0) // Empty
+      area.copy(y = currentY, h = 0)
+    else if (absHeight >= currentH) // Fill remaining area
+      val areaY = currentY
+      val areaH = currentH
+      currentY = area.h
+      currentH = 0
+      area.copy(y = areaY, h = areaH)
+    else if (dirMod * height >= 0) // Fill from the top
+      val areaY = currentY
+      currentY += absHeight + padding
+      currentH -= absHeight + padding
+      area.copy(y = areaY, h = absHeight)
+    else // Fill from the bottom
+      val areaY = currentY + currentH - absHeight
+      currentH -= absHeight + padding
+      area.copy(y = areaY, h = absHeight)
+
+  def apply(height: Int) = nextRow(height)

core/shared/src/main/scala/eu/joaocosta/interim/layouts/StaticColumnAllocator.scala

@@ -0,0 +1,39 @@
+package eu.joaocosta.interim.layouts
+
+import eu.joaocosta.interim._
+
+final class StaticColumnAllocator(
+    val area: Rect,
+    padding: Int,
+    numColumns: Int,
+    alignment: HorizontalAlignment.Left.type | HorizontalAlignment.Right.type
+) extends LayoutAllocator.ColumnAllocator
+    with IndexedSeq[Rect]:
+  val cells: IndexedSeq[Rect] =
+    if (numColumns == 0) Vector.empty
+    else
+      val columnSize    = (area.w - (numColumns - 1) * padding) / numColumns.toDouble
+      val intColumnSize = columnSize.toInt
+      val baseCells = for
+        column <- (0 until numColumns)
+        dx = (column * (columnSize + padding)).toInt
+      yield Rect(area.x + dx, area.y, intColumnSize, area.h)
+      if (alignment == HorizontalAlignment.Left) baseCells
+      else baseCells.reverse
+
+  def apply(i: Int): Rect = cells(i)
+  val length              = cells.length
+
+  private val cellsIterator = cells.iterator
+
+  def nextColumn(): Rect =
+    if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)
+    else cellsIterator.next()
+
+  def nextColumn(width: Int): Rect =
+    if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)
+    else
+      var acc = cellsIterator.next()
+      while (acc.w < width && cellsIterator.hasNext)
+        acc = acc ++ cellsIterator.next()
+      acc

core/shared/src/main/scala/eu/joaocosta/interim/layouts/StaticRowAllocator.scala

@@ -0,0 +1,39 @@
+package eu.joaocosta.interim.layouts
+
+import eu.joaocosta.interim._
+
+final class StaticRowAllocator(
+    val area: Rect,
+    padding: Int,
+    numRows: Int,
+    alignment: VerticalAlignment.Top.type | VerticalAlignment.Bottom.type
+) extends LayoutAllocator.RowAllocator
+    with IndexedSeq[Rect]:
+  val cells: IndexedSeq[Rect] =
+    if (numRows == 0) Vector.empty
+    else
+      val rowSize    = (area.h - (numRows - 1) * padding) / numRows.toDouble
+      val intRowSize = rowSize.toInt
+      val baseCells = for
+        row <- (0 until numRows)
+        dy = (row * (rowSize + padding)).toInt
+      yield Rect(area.x, area.y + dy, area.w, intRowSize)
+      if (alignment == VerticalAlignment.Top) baseCells
+      else baseCells.reverse
+
+  def apply(i: Int): Rect = cells(i)
+  val length              = cells.length
+
+  private val cellsIterator = cells.iterator
+
+  def nextRow(): Rect =
+    if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)
+    else cellsIterator.next()
+
+  def nextRow(height: Int): Rect =
+    if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)
+    else
+      var acc = cellsIterator.next()
+      while (acc.h < height && cellsIterator.hasNext)
+        acc = acc ++ cellsIterator.next()
+      acc

core/shared/src/main/scala/eu/joaocosta/interim/skins/ButtonSkin.scala

@@ -2,7 +2,6 @@ package eu.joaocosta.interim.skins
 
 import eu.joaocosta.interim.TextLayout._
 import eu.joaocosta.interim._
-import eu.joaocosta.interim.api.LayoutAllocator
 import eu.joaocosta.interim.api.Primitives._
 
 trait ButtonSkin:

core/shared/src/main/scala/eu/joaocosta/interim/skins/CheckboxSkin.scala

@@ -1,7 +1,6 @@
 package eu.joaocosta.interim.skins
 
 import eu.joaocosta.interim._
-import eu.joaocosta.interim.api.LayoutAllocator
 import eu.joaocosta.interim.api.Primitives._
 
 trait CheckboxSkin: