ScrollComponent: Implement better specification of direction

api/Elementa.api

@@ -5,6 +5,7 @@ public final class gg/essential/elementa/ElementaVersion : java/lang/Enum {
 	public static final field V2 Lgg/essential/elementa/ElementaVersion;
 	public static final field V3 Lgg/essential/elementa/ElementaVersion;
 	public static final field V4 Lgg/essential/elementa/ElementaVersion;
+	public static final field V5 Lgg/essential/elementa/ElementaVersion;
 	public final fun enableFor (Lkotlin/jvm/functions/Function0;)Ljava/lang/Object;
 	public static fun valueOf (Ljava/lang/String;)Lgg/essential/elementa/ElementaVersion;
 	public static fun values ()[Lgg/essential/elementa/ElementaVersion;
@@ -337,14 +338,17 @@ public final class gg/essential/elementa/components/ScrollComponent : gg/essenti
 	public fun <init> (Ljava/lang/String;)V
 	public fun <init> (Ljava/lang/String;F)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;)V
+	public fun <init> (Ljava/lang/String;FLjava/awt/Color;Lgg/essential/elementa/components/ScrollComponent$Direction;ZZZFFLgg/essential/elementa/UIComponent;)V
+	public synthetic fun <init> (Ljava/lang/String;FLjava/awt/Color;Lgg/essential/elementa/components/ScrollComponent$Direction;ZZZFFLgg/essential/elementa/UIComponent;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;Z)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZ)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZ)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZ)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZF)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZFF)V
 	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZFFLgg/essential/elementa/UIComponent;)V
-	public synthetic fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZFFLgg/essential/elementa/UIComponent;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZFFLgg/essential/elementa/UIComponent;Z)V
+	public synthetic fun <init> (Ljava/lang/String;FLjava/awt/Color;ZZZZFFLgg/essential/elementa/UIComponent;ZILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public synthetic fun addChild (Lgg/essential/elementa/UIComponent;)Lgg/essential/elementa/UIComponent;
 	public fun addChild (Lgg/essential/elementa/UIComponent;)Lgg/essential/elementa/components/ScrollComponent;
 	public final fun addScrollAdjustEvent (ZLkotlin/jvm/functions/Function2;)V
@@ -360,6 +364,7 @@ public final class gg/essential/elementa/components/ScrollComponent : gg/essenti
 	public final fun getEmptyText ()Lgg/essential/elementa/components/UIWrappedText;
 	public final fun getHorizontalOffset ()F
 	public final fun getHorizontalOverhang ()F
+	public final fun getMouseScrollLambda ()Lkotlin/jvm/functions/Function2;
 	public final fun getVerticalOffset ()F
 	public final fun getVerticalOverhang ()F
 	public fun hitTest (FF)Lgg/essential/elementa/UIComponent;
@@ -409,6 +414,15 @@ public final class gg/essential/elementa/components/ScrollComponent$DefaultScrol
 	public final fun getGrip ()Lgg/essential/elementa/UIComponent;
 }
 
+public final class gg/essential/elementa/components/ScrollComponent$Direction : java/lang/Enum {
+	public static final field Horizontal Lgg/essential/elementa/components/ScrollComponent$Direction;
+	public static final field PreferHorizontal Lgg/essential/elementa/components/ScrollComponent$Direction;
+	public static final field PreferVertical Lgg/essential/elementa/components/ScrollComponent$Direction;
+	public static final field Vertical Lgg/essential/elementa/components/ScrollComponent$Direction;
+	public static fun valueOf (Ljava/lang/String;)Lgg/essential/elementa/components/ScrollComponent$Direction;
+	public static fun values ()[Lgg/essential/elementa/components/ScrollComponent$Direction;
+}
+
 public final class gg/essential/elementa/components/ScrollComponent$ScrollChildConstraint : gg/essential/elementa/constraints/HeightConstraint, gg/essential/elementa/constraints/WidthConstraint {
 	public fun <init> (Lgg/essential/elementa/components/ScrollComponent;F)V
 	public synthetic fun <init> (Lgg/essential/elementa/components/ScrollComponent;FILkotlin/jvm/internal/DefaultConstructorMarker;)V

src/main/kotlin/gg/essential/elementa/ElementaVersion.kt

@@ -78,8 +78,14 @@ enum class ElementaVersion {
      * On prior versions, calling [gg.essential.elementa.UIComponent.enableEffect] on a component that wasn't yet initialized would result
      * in the Effect's `beforeDraw` being called once before `setup`.
      */
+    @Deprecated(DEPRECATION_MESSAGE)
     V4,
 
+    /**
+     * Change the behavior of scroll components to no longer require holding down shift when horizontal is the only possible scrolling direction.
+     */
+    V5,
+
     ;
 
     /**
@@ -118,7 +124,9 @@ Be sure to read through all the changes between your current version and your ne
         internal val v2 = V2
         @Suppress("DEPRECATION")
         internal val v3 = V3
+        @Suppress("DEPRECATION")
         internal val v4 = V4
+        internal val v5 = V5
 
 
         @PublishedApi

src/main/kotlin/gg/essential/elementa/components/ScrollComponent.kt

@@ -1,11 +1,13 @@
 package gg.essential.elementa.components
 
+import gg.essential.elementa.ElementaVersion
 import gg.essential.elementa.UIComponent
 import gg.essential.elementa.constraints.*
 import gg.essential.elementa.constraints.animation.Animations
 import gg.essential.elementa.constraints.resolution.ConstraintVisitor
 import gg.essential.elementa.dsl.*
 import gg.essential.elementa.effects.ScissorEffect
+import gg.essential.elementa.events.UIScrollEvent
 import gg.essential.elementa.utils.bindLast
 import gg.essential.universal.UKeyboard
 import gg.essential.universal.UMatrixStack
@@ -20,18 +22,64 @@ import kotlin.math.max
  *
  * Also prevents scrolling past what should be reasonable.
  */
-class ScrollComponent @JvmOverloads constructor(
+class ScrollComponent constructor(
     emptyString: String = "",
     private val innerPadding: Float = 0f,
     private val scrollIconColor: Color = Color.WHITE,
-    private val horizontalScrollEnabled: Boolean = false,
-    private val verticalScrollEnabled: Boolean = true,
+    private val scrollDirection: Direction = Direction.PreferVertical,
     private val horizontalScrollOpposite: Boolean = false,
     private val verticalScrollOpposite: Boolean = false,
+    private val passthroughScroll: Boolean = true,
     private val pixelsPerScroll: Float = 15f,
     private val scrollAcceleration: Float = 1.0f,
     customScissorBoundingBox: UIComponent? = null
 ) : UIContainer() {
+    @JvmOverloads constructor(
+        emptyString: String = "",
+        innerPadding: Float = 0f,
+        scrollIconColor: Color = Color.WHITE,
+        horizontalScrollEnabled: Boolean = false,
+        verticalScrollEnabled: Boolean = true,
+        horizontalScrollOpposite: Boolean = false,
+        verticalScrollOpposite: Boolean = false,
+        pixelsPerScroll: Float = 15f,
+        scrollAcceleration: Float = 1.0f,
+        customScissorBoundingBox: UIComponent? = null,
+        passthroughScroll: Boolean = true
+    ) : this (
+        emptyString,
+        innerPadding,
+        scrollIconColor,
+        when {
+            horizontalScrollEnabled && verticalScrollEnabled -> Direction.PreferVertical
+            horizontalScrollEnabled && !verticalScrollEnabled -> Direction.Horizontal
+            !horizontalScrollEnabled && verticalScrollEnabled -> Direction.Vertical
+            else -> throw IllegalArgumentException("ScrollComponent must have at least one direction of scrolling enabled")
+        },
+        horizontalScrollOpposite,
+        verticalScrollOpposite,
+        passthroughScroll,
+        pixelsPerScroll,
+        scrollAcceleration,
+        customScissorBoundingBox
+    )
+
+    private val primaryScrollDirection
+        get() = when (scrollDirection) {
+            Direction.Horizontal, Direction.PreferHorizontal -> Direction.Horizontal
+            Direction.Vertical, Direction.PreferVertical -> Direction.Vertical
+        }
+    private val secondaryScrollDirection
+        get() = when (scrollDirection) {
+            Direction.PreferHorizontal -> Direction.Vertical
+            Direction.PreferVertical -> Direction.Horizontal
+            else -> null
+        }
+    private val horizontalScrollEnabled
+        get() = primaryScrollDirection == Direction.Horizontal || secondaryScrollDirection == Direction.Horizontal
+    private val verticalScrollEnabled
+        get() = primaryScrollDirection == Direction.Vertical || secondaryScrollDirection == Direction.Vertical
+
     private var animationFPS: Int? = null
 
     private val actualHolder = UIContainer().constrain {
@@ -95,31 +143,45 @@ class ScrollComponent @JvmOverloads constructor(
     val verticalOverhang: Float
         get() = max(0f, calculateActualHeight() - getHeight())
 
+
+
+    val mouseScrollLambda: UIComponent.(UIScrollEvent) -> Unit = {
+        if (Window.of(this).version >= ElementaVersion.v5) {
+            // new behavior
+            val scrollDirection = if (!UKeyboard.isShiftKeyDown()) primaryScrollDirection else secondaryScrollDirection
+            scrollDirection?.let { direction ->
+                if (!onScroll(it.delta.toFloat(), isHorizontal = direction == Direction.Horizontal) && passthroughScroll) {
+                    getNextHighestScrollComponent()?.fireScrollEvent(it)
+                }
+            }
+
+            it.stopPropagation()
+        } else {
+            // old behavior
+            if (UKeyboard.isShiftKeyDown() && horizontalScrollEnabled) {
+                onScroll(it.delta.toFloat(), isHorizontal = true)
+            } else if (!UKeyboard.isShiftKeyDown() && verticalScrollEnabled) {
+                onScroll(it.delta.toFloat(), isHorizontal = false)
+            }
+
+            it.stopPropagation()
+        }
+    }
+
     init {
         this.constrain {
             width = ScrollChildConstraint() coerceAtMost 100.percentOfWindow()
             height = ScrollChildConstraint() coerceAtMost 100.percentOfWindow()
         }
 
-        if (!horizontalScrollEnabled && !verticalScrollEnabled)
-            throw IllegalArgumentException("ScrollComponent must have at least one direction of scrolling enabled")
-
         super.addChild(actualHolder)
         actualHolder.addChild(emptyText)
         this.enableEffects(ScissorEffect(customScissorBoundingBox))
         emptyText.setFontProvider(getFontProvider())
         super.addChild(scrollIconComponent)
         scrollIconComponent.hide(instantly = true)
 
-        onMouseScroll {
-            if (UKeyboard.isShiftKeyDown() && horizontalScrollEnabled) {
-                onScroll(it.delta.toFloat(), isHorizontal = true)
-            } else if (!UKeyboard.isShiftKeyDown() && verticalScrollEnabled) {
-                onScroll(it.delta.toFloat(), isHorizontal = false)
-            }
-
-            it.stopPropagation()
-        }
+        onMouseScroll(mouseScrollLambda)
 
         onMouseClick { event ->
             onClick(event.relativeX, event.relativeY, event.mouseButton)
@@ -228,15 +290,7 @@ class ScrollComponent @JvmOverloads constructor(
             verticalHideScrollWhenUseless = hideWhenUseless
         }
 
-        component.onMouseScroll {
-            if (isHorizontal && horizontalScrollEnabled && UKeyboard.isShiftKeyDown()) {
-                onScroll(it.delta.toFloat(), isHorizontal = true)
-            } else if (!isHorizontal && verticalScrollEnabled) {
-                onScroll(it.delta.toFloat(), isHorizontal = false)
-            }
-
-            it.stopPropagation()
-        }
+        component.onMouseScroll(mouseScrollLambda)
 
         component.onMouseClick { event ->
             if (isHorizontal) {
@@ -378,17 +432,24 @@ class ScrollComponent @JvmOverloads constructor(
         needsUpdate = true
     }
 
-    private fun onScroll(delta: Float, isHorizontal: Boolean) {
-        if (isHorizontal) {
-            horizontalOffset += delta * pixelsPerScroll * currentScrollAcceleration
-        } else {
-            verticalOffset += delta * pixelsPerScroll * currentScrollAcceleration
+    /**
+     * @return whether the offset changed
+     */
+    private fun onScroll(delta: Float, isHorizontal: Boolean): Boolean {
+        var changed = false
+        val offset = if (isHorizontal) ::horizontalOffset else ::verticalOffset
+        val range = calculateOffsetRange(isHorizontal)
+        val newOffset = if(range.isEmpty()) innerPadding else offset.get() + delta * pixelsPerScroll * currentScrollAcceleration
+        if (newOffset in range) {
+            changed = true
+            offset.set(newOffset.coerceIn(range))
         }
 
         currentScrollAcceleration =
             (currentScrollAcceleration + (scrollAcceleration - 1.0f) * 0.15f).coerceIn(0f, scrollAcceleration)
 
         needsUpdate = true
+        return changed
     }
 
     private fun updateScrollBar(scrollPercentage: Float, percentageOfParent: Float, isHorizontal: Boolean) {
@@ -655,6 +716,16 @@ class ScrollComponent @JvmOverloads constructor(
     private fun ClosedFloatingPointRange<Double>.width() = abs(this.start - this.endInclusive)
     private fun ClosedFloatingPointRange<Float>.width() = abs(this.start - this.endInclusive)
 
+    private fun getNextHighestScrollComponent(): ScrollComponent? {
+        var current: UIComponent = this.parent
+
+        while (current !is ScrollComponent && current.hasParent && current.parent != current) {
+            current = current.parent
+        }
+
+        return current as? ScrollComponent
+    }
+
     class DefaultScrollBar(isHorizontal: Boolean) : UIComponent() {
         val grip: UIComponent
 
@@ -743,6 +814,13 @@ class ScrollComponent @JvmOverloads constructor(
 
     }
 
+    enum class Direction {
+        Vertical,
+        Horizontal,
+        /*BothBut*/PreferVertical,
+        /*BothBut*/PreferHorizontal,
+    }
+
     companion object {
 
         fun getScrollImage(): UIImage {