Merge pull request #109 from JD557/one-frame-delay

Add scratch state to UI context

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

@@ -1,6 +1,6 @@
 package eu.joaocosta.interim
 
-import eu.joaocosta.interim.TextLayout.*
+import eu.joaocosta.interim.TextLayout._
 
 /** Object with all the DSL operations.
   *
@@ -21,14 +21,15 @@ object InterIm extends api.Primitives with api.Layouts with api.Components with
       run: (historicalInputState: InputState.Historical, uiContext: UiContext) ?=> T
   ): (List[RenderOp], T) =
     // prepare
+    uiContext.commit()
     uiContext.ops.clear()
     uiContext.currentZ = 0
-    uiContext.hotItem = None
+    uiContext.scratchItemState.hotItem = None
     val historicalInputState = uiContext.pushInputState(inputState)
-    if (inputState.mouseInput.isPressed) uiContext.selectedItem = None
+    if (inputState.mouseInput.isPressed) uiContext.scratchItemState.selectedItem = None
     // run
     val res = run(using historicalInputState, uiContext)
     // finish
-    if (!historicalInputState.mouseInput.isPressed) uiContext.activeItem = None
+    if (!historicalInputState.mouseInput.isPressed) uiContext.scratchItemState.activeItem = None
     // return
     (uiContext.getOrderedOps(), res)

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

@@ -12,25 +12,30 @@ import scala.collection.mutable
 final class UiContext private (
     private[interim] var currentZ: Int,
     private[interim] var previousInputState: Option[InputState],
-    private[interim] var hotItem: Option[(Int, ItemId)], // Item being hovered by the mouse
-    private[interim] var activeItem: Option[ItemId],     // Item being clicked by the mouse
-    private[interim] var selectedItem: Option[ItemId],   // Last item clicked
+    private[interim] var currentItemState: UiContext.ItemState,
+    private[interim] var scratchItemState: UiContext.ItemState,
     private[interim] val ops: mutable.TreeMap[Int, mutable.Queue[RenderOp]]
 ):
 
+  private def getItemStatus(id: ItemId)(using inputState: InputState): UiContext.ItemStatus =
+    currentItemState.getItemStatus(id)
+
+  private def getScratchItemStatus(id: ItemId)(using inputState: InputState): UiContext.ItemStatus =
+    scratchItemState.getItemStatus(id)
+
   private def registerItem(id: ItemId, area: Rect, passive: Boolean)(using
       inputState: InputState
   ): UiContext.ItemStatus =
-    if (area.isMouseOver && hotItem.forall((hotZ, _) => hotZ <= currentZ))
-      hotItem = Some(currentZ -> id)
-      if (!passive && (activeItem == None || activeItem == Some(id)) && inputState.mouseInput.isPressed)
-        activeItem = Some(id)
-        selectedItem = Some(id)
-    val hot      = hotItem.map(_._2) == Some(id)
-    val active   = activeItem == Some(id)
-    val selected = selectedItem == Some(id)
-    val clicked  = hot && active && inputState.mouseInput.isPressed == false
-    UiContext.ItemStatus(hot, active, selected, clicked)
+    if (area.isMouseOver && scratchItemState.hotItem.forall((hotZ, _) => hotZ <= currentZ))
+      scratchItemState.hotItem = Some(currentZ -> id)
+      if (inputState.mouseInput.isPressed)
+        if (passive && currentItemState.activeItem == None)
+          scratchItemState.activeItem = None
+          scratchItemState.selectedItem = None
+        else if (!passive && currentItemState.activeItem.forall(_ == id))
+          scratchItemState.activeItem = Some(id)
+          scratchItemState.selectedItem = Some(id)
+    getItemStatus(id)
 
   private[interim] def getOrderedOps(): List[RenderOp] =
     ops.values.toList.flatten
@@ -46,26 +51,27 @@ final class UiContext private (
     previousInputState = Some(inputState)
     history
 
-  def this() = this(0, None, None, None, None, new mutable.TreeMap())
+  private[interim] def commit(): this.type =
+    currentItemState = scratchItemState.clone()
+    this
+
+  def this() = this(0, None, UiContext.ItemState(), UiContext.ItemState(), new mutable.TreeMap())
 
   override def clone(): UiContext =
     new UiContext(
       currentZ,
       previousInputState,
-      hotItem,
-      activeItem,
-      selectedItem,
+      currentItemState.clone(),
+      scratchItemState.clone(),
       ops.clone().mapValuesInPlace((_, v) => v.clone())
     )
 
   def fork(): UiContext =
-    new UiContext(currentZ, previousInputState, hotItem, activeItem, selectedItem, new mutable.TreeMap())
+    new UiContext(currentZ, previousInputState, currentItemState, scratchItemState, new mutable.TreeMap())
 
   def ++=(that: UiContext): this.type =
     // previousInputState stays the same
-    this.hotItem = that.hotItem
-    this.activeItem = that.activeItem
-    this.selectedItem = that.selectedItem
+    this.scratchItemState = that.scratchItemState.clone()
     that.ops.foreach: (z, ops) =>
       if (this.ops.contains(z)) this.ops(z) ++= that.ops(z)
       else this.ops(z) = that.ops(z)
@@ -77,6 +83,20 @@ final class UiContext private (
     this
 
 object UiContext:
+  private[interim] class ItemState(
+      var hotItem: Option[(Int, ItemId)] = None, // Item being hovered by the mouse
+      var activeItem: Option[ItemId] = None,     // Item being clicked by the mouse
+      var selectedItem: Option[ItemId] = None    // Last item clicked
+  ):
+    def getItemStatus(id: ItemId)(using inputState: InputState): UiContext.ItemStatus =
+      val hot      = hotItem.map(_._2) == Some(id)
+      val active   = activeItem == Some(id)
+      val selected = selectedItem == Some(id)
+      val clicked  = hot && active && inputState.mouseInput.isPressed == false
+      UiContext.ItemStatus(hot, active, selected, clicked)
+
+    override def clone(): ItemState = new ItemState(hotItem, activeItem, selectedItem)
+
   /** Status of an item.
     *
     *  @param hot if the mouse is on top of the item
@@ -92,7 +112,12 @@ object UiContext:
     *
     * Components register themselves on every frame to update and check their status.
     *
-    * Note that this is only required when creating new components.
+    * This is only required when creating new components. If you are using the premade components
+    * you do not need to call this.
+    *
+    * Also of note is that this method returns the status from computed in the previous iteration,
+    * as that's the only consistent information.
+    * If you need the status as it's being computed, check [[getScratchItemStatus]].
     *
     * @param id Item ID to register
     * @param area the area of this component
@@ -106,6 +131,33 @@ object UiContext:
   ): UiContext.ItemStatus =
     uiContext.registerItem(id, area, passive)
 
+  /** Checks the status of a component from the previous UI computation without registering it.
+    *
+    *  This method can be used if one needs to check the status of an item in the previous iteration
+    *  without registering it.
+    * @param id Item ID to register
+    * @return the item status of the component.
+    */
+  def getItemStatus(id: ItemId)(using
+      uiContext: UiContext,
+      inputState: InputState
+  ): UiContext.ItemStatus =
+    uiContext.getItemStatus(id)
+
+  /** Checks the status of a component at the current point in the UI computation without registering it.
+    *
+    * This method can be used if one needs to check the status of an item in the middle of the current iteration.
+    *
+    * This is can return inconsistent state, and is only recommended for unit tests or debugging.
+    * @param id Item ID to register
+    * @return the item status of the component.
+    */
+  def getScratchItemStatus(id: ItemId)(using
+      uiContext: UiContext,
+      inputState: InputState
+  ): UiContext.ItemStatus =
+    uiContext.getScratchItemStatus(id)
+
   /** Applies the operations in a code block at a specified z-index
     *  (higher z-indices show on front of lower z-indices).
     */

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

@@ -1,7 +1,7 @@
 package eu.joaocosta.interim.api
 
-import eu.joaocosta.interim.*
-import eu.joaocosta.interim.skins.*
+import eu.joaocosta.interim._
+import eu.joaocosta.interim.skins._
 
 /** Object containing the default components.
   *
@@ -102,12 +102,13 @@ trait Components:
         if (value.get.isOpen)
           value.modifyIf(!itemStatus.selected)(_.close)
           val selectableLabels = labels.drop(if (undefinedFirstValue) 1 else 0)
-          selectableLabels.zipWithIndex
-            .foreach: (label, idx) =>
-              val selectOptionArea = skin.selectOptionArea(area, idx)
-              val optionStatus     = UiContext.registerItem(id |> idx, selectOptionArea)
-              skin.renderSelectOption(area, idx, selectableLabels, optionStatus)
-              if (optionStatus.active) value := PanelState.closed(if (undefinedFirstValue) idx + 1 else idx)
+          Primitives.onTop:
+            selectableLabels.zipWithIndex
+              .foreach: (label, idx) =>
+                val selectOptionArea = skin.selectOptionArea(area, idx)
+                val optionStatus     = UiContext.registerItem(id |> idx, selectOptionArea)
+                skin.renderSelectOption(area, idx, selectableLabels, optionStatus)
+                if (optionStatus.active) value := PanelState.closed(if (undefinedFirstValue) idx + 1 else idx)
 
   /** Slider component. Returns the current position of the slider, between min and max.
     *

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

@@ -1,7 +1,7 @@
 package eu.joaocosta.interim.skins
 
-import eu.joaocosta.interim.*
-import eu.joaocosta.interim.api.Primitives.*
+import eu.joaocosta.interim._
+import eu.joaocosta.interim.api.Primitives._
 
 trait SelectSkin:
   def selectBoxArea(area: Rect): Rect
@@ -56,22 +56,21 @@ object SelectSkin extends DefaultSkin:
     ): Unit =
       val selectOptionArea = this.selectOptionArea(area, value)
       val optionLabel      = labels.applyOrElse(value, _ => "")
-      onTop:
-        itemStatus match
-          case UiContext.ItemStatus(_, _, true, _) | UiContext.ItemStatus(_, true, _, _) =>
-            rectangle(selectOptionArea, colorScheme.primaryHighlight)
-          case UiContext.ItemStatus(true, _, _, _) =>
-            rectangle(selectOptionArea, colorScheme.secondaryHighlight)
-          case _ =>
-            rectangle(selectOptionArea, colorScheme.secondary)
-        text(
-          selectOptionArea.shrink(padding),
-          colorScheme.text,
-          optionLabel,
-          font,
-          TextLayout.HorizontalAlignment.Left,
-          TextLayout.VerticalAlignment.Center
-        )
+      itemStatus match
+        case UiContext.ItemStatus(_, _, true, _) | UiContext.ItemStatus(_, true, _, _) =>
+          rectangle(selectOptionArea, colorScheme.primaryHighlight)
+        case UiContext.ItemStatus(true, _, _, _) =>
+          rectangle(selectOptionArea, colorScheme.secondaryHighlight)
+        case _ =>
+          rectangle(selectOptionArea, colorScheme.secondary)
+      text(
+        selectOptionArea.shrink(padding),
+        colorScheme.text,
+        optionLabel,
+        font,
+        TextLayout.HorizontalAlignment.Left,
+        TextLayout.VerticalAlignment.Center
+      )
 
   val lightDefault: Default = Default(
     padding = 2,

core/shared/src/test/scala/eu/joaocosta/interim/UiContextSpec.scala

@@ -5,45 +5,59 @@ class UiContextSpec extends munit.FunSuite:
   test("registerItem should not mark an item not under the cursor"):
     given uiContext: UiContext   = new UiContext()
     given inputState: InputState = InputState(0, 0, false, "")
-    val itemStatus               = UiContext.registerItem(1, Rect(1, 1, 10, 10))
+
+    UiContext.registerItem(1, Rect(1, 1, 10, 10))
+    assertEquals(uiContext.scratchItemState.hotItem, None)
+    assertEquals(uiContext.scratchItemState.activeItem, None)
+    assertEquals(uiContext.scratchItemState.selectedItem, None)
+
+    val itemStatus = UiContext.getScratchItemStatus(1)
     assertEquals(itemStatus.hot, false)
     assertEquals(itemStatus.active, false)
     assertEquals(itemStatus.selected, false)
     assertEquals(itemStatus.clicked, false)
-    assertEquals(uiContext.hotItem, None)
-    assertEquals(uiContext.activeItem, None)
-    assertEquals(uiContext.selectedItem, None)
 
   test("registerItem should mark an item under the cursor as hot"):
     given uiContext: UiContext   = new UiContext()
     given inputState: InputState = InputState(5, 5, false, "")
-    val itemStatus               = UiContext.registerItem(1, Rect(1, 1, 10, 10))
+
+    UiContext.registerItem(1, Rect(1, 1, 10, 10))
+    assertEquals(uiContext.scratchItemState.hotItem, Some(0 -> 1))
+    assertEquals(uiContext.scratchItemState.activeItem, None)
+    assertEquals(uiContext.scratchItemState.selectedItem, None)
+
+    val itemStatus = UiContext.getScratchItemStatus(1)
     assertEquals(itemStatus.hot, true)
     assertEquals(itemStatus.active, false)
     assertEquals(itemStatus.selected, false)
     assertEquals(itemStatus.clicked, false)
-    assertEquals(uiContext.hotItem, Some(0 -> 1))
-    assertEquals(uiContext.activeItem, None)
-    assertEquals(uiContext.selectedItem, None)
 
   test("registerItem should mark a clicked item as active and focused"):
     given uiContext: UiContext   = new UiContext()
     given inputState: InputState = InputState(5, 5, true, "")
-    val itemStatus               = UiContext.registerItem(1, Rect(1, 1, 10, 10))
+
+    UiContext.registerItem(1, Rect(1, 1, 10, 10))
+    assertEquals(uiContext.scratchItemState.hotItem, Some(0 -> 1))
+    assertEquals(uiContext.scratchItemState.activeItem, Some(1))
+    assertEquals(uiContext.scratchItemState.selectedItem, Some(1))
+
+    val itemStatus = UiContext.getScratchItemStatus(1)
     assertEquals(itemStatus.hot, true)
     assertEquals(itemStatus.active, true)
     assertEquals(itemStatus.selected, true)
     assertEquals(itemStatus.clicked, false)
-    assertEquals(uiContext.hotItem, Some(0 -> 1))
-    assertEquals(uiContext.activeItem, Some(1))
-    assertEquals(uiContext.selectedItem, Some(1))
 
   test("registerItem should mark a clicked item as clicked once the mouse is released"):
     val uiContext: UiContext    = new UiContext()
     val inputState1: InputState = InputState(5, 5, true, "")
     UiContext.registerItem(1, Rect(1, 1, 10, 10))(using uiContext, inputState1)
+    uiContext.commit()
+
     val inputState2: InputState = InputState(5, 5, false, "")
-    val itemStatus              = UiContext.registerItem(1, Rect(1, 1, 10, 10))(using uiContext, inputState2)
+    UiContext.registerItem(1, Rect(1, 1, 10, 10))(using uiContext, inputState2)
+    uiContext.commit()
+
+    val itemStatus = UiContext.getItemStatus(1)(using uiContext, inputState2)
     assertEquals(itemStatus.hot, true)
     assertEquals(itemStatus.active, true)
     assertEquals(itemStatus.selected, true)
@@ -53,16 +67,21 @@ class UiContextSpec extends munit.FunSuite:
     val uiContext   = new UiContext()
     val inputState1 = InputState(5, 5, true, "")
     UiContext.registerItem(1, Rect(1, 1, 10, 10))(using uiContext, inputState1)
+    uiContext.commit()
+
     val inputState2 = InputState(20, 20, true, "")
     UiContext.registerItem(1, Rect(1, 1, 10, 10))(using uiContext, inputState2)
-    val itemStatus = UiContext.registerItem(2, Rect(15, 15, 10, 10))(using uiContext, inputState2)
+    UiContext.registerItem(2, Rect(15, 15, 10, 10))(using uiContext, inputState2)
+    assertEquals(uiContext.scratchItemState.hotItem, Some(0 -> 2))
+    assertEquals(uiContext.scratchItemState.activeItem, Some(1))
+    assertEquals(uiContext.scratchItemState.selectedItem, Some(1))
+    uiContext.commit()
+
+    val itemStatus = UiContext.getItemStatus(2)(using uiContext, inputState2)
     assertEquals(itemStatus.hot, true)
     assertEquals(itemStatus.active, false)
     assertEquals(itemStatus.selected, false)
     assertEquals(itemStatus.clicked, false)
-    assertEquals(uiContext.hotItem, Some(0 -> 2))
-    assertEquals(uiContext.activeItem, Some(1))
-    assertEquals(uiContext.selectedItem, Some(1))
 
   test("fork should create a new UiContext with no ops, and merge them back with ++="):
     val uiContext: UiContext = new UiContext()

core/shared/src/test/scala/eu/joaocosta/interim/api/LayoutsSpec.scala

@@ -14,17 +14,17 @@ class LayoutsSpec extends munit.FunSuite:
   test("clip ignores input outside the clip area"):
     given uiContext: UiContext   = new UiContext()
     given inputState: InputState = InputState(5, 5, false, "")
-    val itemStatus =
-      Layouts.clip(Rect(10, 10, 10, 10)):
-        UiContext.registerItem(1, Rect(0, 0, 15, 15))
+    Layouts.clip(Rect(10, 10, 10, 10)):
+      UiContext.registerItem(1, Rect(0, 0, 15, 15))
+    val itemStatus = UiContext.getScratchItemStatus(1)
     assertEquals(itemStatus.hot, false)
 
   test("clip considers input inside the clip area"):
     given uiContext: UiContext   = new UiContext()
     given inputState: InputState = InputState(12, 12, false, "")
-    val itemStatus =
-      Layouts.clip(Rect(10, 10, 10, 10)):
-        UiContext.registerItem(1, Rect(0, 0, 15, 15))
+    Layouts.clip(Rect(10, 10, 10, 10)):
+      UiContext.registerItem(1, Rect(0, 0, 15, 15))
+    val itemStatus = UiContext.getScratchItemStatus(1)
     assertEquals(itemStatus.hot, true)
 
   test("grid correctly lays out elements in a grid"):