Split allocators into area and cell allocators

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

@@ -1,24 +1,40 @@
 package eu.joaocosta.interim
 
-import eu.joaocosta.interim.{Font, HorizontalAlignment, Rect, TextLayout, VerticalAlignment}
+import eu.joaocosta.interim._
 
-/** A layout allocator is a side-effectful function that, given a size (width or height) tries to allocate
-  * a new area.
+/** A layout allocator is a side-effectful function that tries to allocate some space inside of an area.
   *
   * Note that calls to this function are side effectful, as each call reserves an area.
   */
-trait LayoutAllocator:
+sealed 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)
+object LayoutAllocator:
+  /** Allocator that allows one to allocate space based on a required area.
+    */
+  trait AreaAllocator extends LayoutAllocator:
+    def allocate(width: Int, height: Int): Rect
+    def fill(): Rect = allocate(Int.MaxValue, Int.MaxValue)
+    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)
+  /** Allocator that allows one to request new cells.
+    *
+    * The preallocated cells can also be accessed as an `IndexedSeq`
+    */
+  trait CellAllocator extends LayoutAllocator with IndexedSeq[Rect]:
+    lazy val cells: IndexedSeq[Rect]
+    protected lazy val cellsIterator = cells.iterator
+
+    def apply(i: Int): Rect = cells(i)
+    val length              = cells.length
+
+    def nextCell(): Rect =
+      if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)
+      else cellsIterator.next()
 
-object LayoutAllocator:
   trait RowAllocator extends LayoutAllocator:
     def nextRow(height: Int): Rect
     def allocate(width: Int, height: Int): Rect = nextRow(height)

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

@@ -14,11 +14,11 @@ trait Components:
   type Component[+T] = (inputState: InputState.Historical, uiContext: UiContext) ?=> T
 
   trait ComponentWithValue[T]:
-    def allocateArea(using allocator: LayoutAllocator): Rect
+    def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect
 
     def render(area: Rect, value: Ref[T]): Component[Unit]
 
-    def render(value: Ref[T])(using allocator: LayoutAllocator): Component[Unit] =
+    def render(value: Ref[T])(using allocator: LayoutAllocator.AreaAllocator): Component[Unit] =
       render(allocateArea, value)
 
     def applyRef(area: Rect, value: Ref[T]): Component[T] =
@@ -32,23 +32,25 @@ trait Components:
       case x: T      => applyValue(area, x)
       case x: Ref[T] => applyRef(area, x)
 
-    inline def apply(value: T | Ref[T])(using allocator: LayoutAllocator): Component[T] = apply(allocateArea, value)
+    inline def apply(value: T | Ref[T])(using allocator: LayoutAllocator.AreaAllocator): Component[T] =
+      apply(allocateArea, value)
 
   trait ComponentWithBody[I, F[_]]:
-    def allocateArea(using allocator: LayoutAllocator): Rect
+    def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect
 
     def render[T](area: Rect, body: I => T): Component[F[T]]
 
-    def render[T](body: I => T)(using allocator: LayoutAllocator): Component[Unit] =
+    def render[T](body: I => T)(using allocator: LayoutAllocator.AreaAllocator): Component[Unit] =
       render(allocateArea, body)
 
     def apply[T](area: Rect)(body: I => T): Component[F[T]] = render(area, body)
 
     def apply[T](area: Rect)(body: => T)(using ev: I =:= Unit): Component[F[T]] = render(area, _ => body)
 
-    def apply[T](body: I => T)(using allocator: LayoutAllocator): Component[F[T]] = render(allocateArea, body)
+    def apply[T](body: I => T)(using allocator: LayoutAllocator.AreaAllocator): Component[F[T]] =
+      render(allocateArea, body)
 
-    def apply[T](body: => T)(using allocator: LayoutAllocator, ev: I =:= Unit): Component[F[T]] =
+    def apply[T](body: => T)(using allocator: LayoutAllocator.AreaAllocator, ev: I =:= Unit): Component[F[T]] =
       render(allocateArea, _ => body)
 
   /** Button component. Returns true if it's being clicked, false otherwise.
@@ -61,7 +63,7 @@ trait Components:
       skin: ButtonSkin = ButtonSkin.default()
   ): ComponentWithBody[Unit, Option] =
     new ComponentWithBody[Unit, Option]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator, label)
 
       def render[T](area: Rect, body: Unit => T): Component[Option[T]] =
@@ -77,7 +79,7 @@ trait Components:
       skin: CheckboxSkin = CheckboxSkin.default()
   ): ComponentWithValue[Boolean] =
     new ComponentWithValue[Boolean]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[Boolean]): Component[Unit] =
@@ -99,7 +101,7 @@ trait Components:
       skin: ButtonSkin = ButtonSkin.default()
   ): ComponentWithValue[T] =
     new ComponentWithValue[T]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator, label)
 
       def render(area: Rect, value: Ref[T]): Component[Unit] =
@@ -121,7 +123,7 @@ trait Components:
       skin: SelectSkin = SelectSkin.default()
   ): ComponentWithValue[PanelState[Int]] =
     new ComponentWithValue[PanelState[Int]]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator, labels)
 
       def render(area: Rect, value: Ref[PanelState[Int]]): Component[Unit] =
@@ -152,7 +154,7 @@ trait Components:
       skin: SliderSkin = SliderSkin.default()
   ): ComponentWithValue[Int] =
     new ComponentWithValue[Int]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[Int]): Component[Unit] =
@@ -175,7 +177,7 @@ trait Components:
       skin: TextInputSkin = TextInputSkin.default()
   ): ComponentWithValue[String] =
     new ComponentWithValue[String]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[String]): Component[Unit] =
@@ -191,7 +193,7 @@ trait Components:
     */
   final def moveHandle(id: ItemId, skin: HandleSkin = HandleSkin.default()): ComponentWithValue[Rect] =
     new ComponentWithValue[Rect]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[Rect]): Component[Unit] =
@@ -209,7 +211,7 @@ trait Components:
     */
   final def resizeHandle(id: ItemId, skin: HandleSkin = HandleSkin.default()): ComponentWithValue[Rect] =
     new ComponentWithValue[Rect]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[Rect]): Component[Unit] =
@@ -230,7 +232,7 @@ trait Components:
       skin: HandleSkin = HandleSkin.default()
   ): ComponentWithValue[PanelState[T]] =
     new ComponentWithValue[PanelState[T]]:
-      def allocateArea(using allocator: LayoutAllocator): Rect =
+      def allocateArea(using allocator: LayoutAllocator.AreaAllocator): Rect =
         skin.allocateArea(allocator)
 
       def render(area: Rect, value: Ref[PanelState[T]]): Component[Unit] =

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

@@ -12,16 +12,26 @@ trait Primitives:
 
   /** Draws a rectangle filling the specified area with a color.
     */
-  final def rectangle(area: Rect, color: Color)(using uiContext: UiContext): Unit =
-    uiContext.pushRenderOp(RenderOp.DrawRect(area, color))
+  final def rectangle(area: Rect | LayoutAllocator.CellAllocator, color: Color)(using uiContext: UiContext): Unit =
+    val reservedArea = area match {
+      case rect: Rect                           => rect
+      case alloc: LayoutAllocator.CellAllocator => alloc.nextCell()
+    }
+    uiContext.pushRenderOp(RenderOp.DrawRect(reservedArea, color))
 
   /** Draws the outline a rectangle inside the specified area with a color.
     */
-  final def rectangleOutline(area: Rect, color: Color, strokeSize: Int)(using uiContext: UiContext): Unit =
-    val top    = area.copy(h = strokeSize)
-    val bottom = top.move(dx = 0, dy = area.h - strokeSize)
-    val left   = area.copy(w = strokeSize)
-    val right  = left.move(dx = area.w - strokeSize, dy = 0)
+  final def rectangleOutline(area: Rect | LayoutAllocator.CellAllocator, color: Color, strokeSize: Int)(using
+      uiContext: UiContext
+  ): Unit =
+    val reservedArea = area match {
+      case rect: Rect                           => rect
+      case alloc: LayoutAllocator.CellAllocator => alloc.nextCell()
+    }
+    val top    = reservedArea.copy(h = strokeSize)
+    val bottom = top.move(dx = 0, dy = reservedArea.h - strokeSize)
+    val left   = reservedArea.copy(w = strokeSize)
+    val right  = left.move(dx = reservedArea.w - strokeSize, dy = 0)
     rectangle(top, color)
     rectangle(bottom, color)
     rectangle(left, color)
@@ -35,7 +45,7 @@ trait Primitives:
     * @param verticalAlignment how the text should be aligned vertically
     */
   final def text(
-      area: Rect | LayoutAllocator,
+      area: Rect | LayoutAllocator.AreaAllocator,
       color: Color,
       message: String,
       font: Font = Font.default,
@@ -46,8 +56,8 @@ trait Primitives:
   ): Unit =
     if (message.nonEmpty)
       val reservedArea = area match {
-        case rect: Rect             => rect
-        case alloc: LayoutAllocator => alloc.allocate(message, font)
+        case rect: Rect                           => rect
+        case alloc: LayoutAllocator.AreaAllocator => alloc.allocate(message, font)
       }
       uiContext.pushRenderOp(
         RenderOp.DrawText(reservedArea, color, message, font, reservedArea, horizontalAlignment, verticalAlignment)

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

@@ -7,6 +7,7 @@ final class DynamicColumnAllocator(
     padding: Int,
     alignment: HorizontalAlignment.Left.type | HorizontalAlignment.Right.type
 ) extends LayoutAllocator.ColumnAllocator
+    with LayoutAllocator.AreaAllocator
     with (Int => Rect):
   private var currentX = area.x
   private var currentW = area.w

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

@@ -7,6 +7,7 @@ final class DynamicRowAllocator(
     padding: Int,
     alignment: VerticalAlignment.Top.type | VerticalAlignment.Bottom.type
 ) extends LayoutAllocator.RowAllocator
+    with LayoutAllocator.AreaAllocator
     with (Int => Rect):
   private var currentY = area.y
   private var currentH = area.h

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

@@ -8,8 +8,9 @@ final class StaticColumnAllocator(
     numColumns: Int,
     alignment: HorizontalAlignment.Left.type | HorizontalAlignment.Right.type
 ) extends LayoutAllocator.ColumnAllocator
-    with IndexedSeq[Rect]:
-  val cells: IndexedSeq[Rect] =
+    with LayoutAllocator.AreaAllocator
+    with LayoutAllocator.CellAllocator:
+  lazy val cells: IndexedSeq[Rect] =
     if (numColumns == 0) Vector.empty
     else
       val columnSize    = (area.w - (numColumns - 1) * padding) / numColumns.toDouble
@@ -21,14 +22,7 @@ final class StaticColumnAllocator(
       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(): Rect = nextCell()
 
   def nextColumn(width: Int): Rect =
     if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)

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

@@ -8,8 +8,9 @@ final class StaticRowAllocator(
     numRows: Int,
     alignment: VerticalAlignment.Top.type | VerticalAlignment.Bottom.type
 ) extends LayoutAllocator.RowAllocator
-    with IndexedSeq[Rect]:
-  val cells: IndexedSeq[Rect] =
+    with LayoutAllocator.AreaAllocator
+    with LayoutAllocator.CellAllocator:
+  lazy val cells: IndexedSeq[Rect] =
     if (numRows == 0) Vector.empty
     else
       val rowSize    = (area.h - (numRows - 1) * padding) / numRows.toDouble
@@ -21,14 +22,7 @@ final class StaticRowAllocator(
       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(): Rect = nextCell()
 
   def nextRow(height: Int): Rect =
     if (!cellsIterator.hasNext) area.copy(w = 0, h = 0)

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

@@ -5,7 +5,7 @@ import eu.joaocosta.interim._
 import eu.joaocosta.interim.api.Primitives._
 
 trait ButtonSkin:
-  def allocateArea(allocator: LayoutAllocator, label: String): Rect
+  def allocateArea(allocator: LayoutAllocator.AreaAllocator, label: String): Rect
   def buttonArea(area: Rect): Rect
   def renderButton(area: Rect, label: String, itemStatus: UiContext.ItemStatus)(using
       uiContext: UiContext
@@ -19,7 +19,7 @@ object ButtonSkin extends DefaultSkin:
       colorScheme: ColorScheme
   ) extends ButtonSkin:
 
-    def allocateArea(allocator: LayoutAllocator, label: String): Rect =
+    def allocateArea(allocator: LayoutAllocator.AreaAllocator, label: String): Rect =
       allocator.allocate(label, font, paddingH = buttonHeight / 2)
 
     def buttonArea(area: Rect): Rect =

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

@@ -4,7 +4,7 @@ import eu.joaocosta.interim._
 import eu.joaocosta.interim.api.Primitives._
 
 trait CheckboxSkin:
-  def allocateArea(allocator: LayoutAllocator): Rect
+  def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect
   def checkboxArea(area: Rect): Rect
   def renderCheckbox(area: Rect, value: Boolean, itemStatus: UiContext.ItemStatus)(using uiContext: UiContext): Unit
 
@@ -15,7 +15,7 @@ object CheckboxSkin extends DefaultSkin:
       colorScheme: ColorScheme
   ) extends CheckboxSkin:
 
-    def allocateArea(allocator: LayoutAllocator): Rect =
+    def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect =
       allocator.allocate(Font.default.fontSize, Font.default.fontSize)
 
     def checkboxArea(area: Rect): Rect =

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

@@ -4,7 +4,7 @@ import eu.joaocosta.interim._
 import eu.joaocosta.interim.api.Primitives._
 
 trait HandleSkin:
-  def allocateArea(allocator: LayoutAllocator): Rect
+  def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect
 
   def moveHandleArea(area: Rect): Rect
   def closeHandleArea(area: Rect): Rect
@@ -18,7 +18,7 @@ object HandleSkin extends DefaultSkin:
 
   final case class Default(colorScheme: ColorScheme) extends HandleSkin:
 
-    def allocateArea(allocator: LayoutAllocator): Rect =
+    def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect =
       allocator.allocate(Font.default.fontSize, Font.default.fontSize)
 
     def moveHandleArea(area: Rect): Rect =

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

@@ -4,7 +4,7 @@ import eu.joaocosta.interim._
 import eu.joaocosta.interim.api.Primitives._
 
 trait SelectSkin:
-  def allocateArea(allocator: LayoutAllocator, labels: Vector[String]): Rect
+  def allocateArea(allocator: LayoutAllocator.AreaAllocator, labels: Vector[String]): Rect
 
   def selectBoxArea(area: Rect): Rect
   def renderSelectBox(area: Rect, value: Int, labels: Vector[String], itemStatus: UiContext.ItemStatus)(using
@@ -24,7 +24,7 @@ object SelectSkin extends DefaultSkin:
       colorScheme: ColorScheme
   ) extends SelectSkin:
 
-    def allocateArea(allocator: LayoutAllocator, labels: Vector[String]): Rect =
+    def allocateArea(allocator: LayoutAllocator.AreaAllocator, labels: Vector[String]): Rect =
       val largestLabel = labels.maxByOption(_.size).getOrElse("")
       allocator.allocate(largestLabel, font, paddingW = padding, paddingH = padding)
 

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

@@ -4,7 +4,7 @@ import eu.joaocosta.interim._
 import eu.joaocosta.interim.api.Primitives._
 
 trait SliderSkin:
-  def allocateArea(allocator: LayoutAllocator): Rect
+  def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect
   def sliderArea(area: Rect): Rect
   def renderSlider(area: Rect, min: Int, value: Int, max: Int, itemStatus: UiContext.ItemStatus)(using
       uiContext: UiContext
@@ -18,7 +18,7 @@ object SliderSkin extends DefaultSkin:
       colorScheme: ColorScheme
   ) extends SliderSkin:
 
-    def allocateArea(allocator: LayoutAllocator): Rect =
+    def allocateArea(allocator: LayoutAllocator.AreaAllocator): Rect =
       allocator.allocate(Font.default.fontSize + 2 * padding, Font.default.fontSize + 2 * padding)
 
     def sliderArea(area: Rect): Rect = area.shrink(padding)