Add clip element and fix clipping bug on iOS

element/api/element.api

@@ -25,6 +25,22 @@ public abstract interface class com/juul/krayon/element/ClickHandler {
 	public abstract fun onClick (Ljava/lang/Object;)V
 }
 
+public final class com/juul/krayon/element/ClipElement : com/juul/krayon/element/Element {
+	public static final field Companion Lcom/juul/krayon/element/ClipElement$Companion;
+	public fun <init> ()V
+	public fun draw (Lcom/juul/krayon/kanvas/Kanvas;)V
+	public final fun getClip ()Lcom/juul/krayon/kanvas/Clip;
+	public fun getTag ()Ljava/lang/String;
+	public final fun setClip (Lcom/juul/krayon/kanvas/Clip;)V
+}
+
+public final class com/juul/krayon/element/ClipElement$Companion : com/juul/krayon/element/ElementBuilder, com/juul/krayon/element/ElementSelector {
+	public fun build ()Lcom/juul/krayon/element/ClipElement;
+	public synthetic fun build ()Lcom/juul/krayon/element/Element;
+	public fun trySelect (Lcom/juul/krayon/element/Element;)Lcom/juul/krayon/element/ClipElement;
+	public synthetic fun trySelect (Lcom/juul/krayon/element/Element;)Lcom/juul/krayon/element/Element;
+}
+
 public abstract class com/juul/krayon/element/Element {
 	public static final field Companion Lcom/juul/krayon/element/Element$Companion;
 	public fun <init> ()V

element/src/commonMain/kotlin/ClipElement.kt

@@ -0,0 +1,31 @@
+package com.juul.krayon.element
+
+import com.juul.krayon.kanvas.Clip
+import com.juul.krayon.kanvas.Kanvas
+import com.juul.krayon.kanvas.withClip
+
+/**
+ * An element that clips rendering of child elements.
+ *
+ * Note that this does not prevent clipped children from being hit-tested for interactions.
+ */
+public class ClipElement : Element() {
+
+    override val tag: String get() = "clip"
+
+    public var clip: Clip? by attributes.withDefault { null }
+
+    override fun draw(kanvas: Kanvas) {
+        when (val clip = this.clip) {
+            null -> children.forEach { it.draw(kanvas) }
+            else -> kanvas.withClip(clip) {
+                children.forEach { it.draw(kanvas) }
+            }
+        }
+    }
+
+    public companion object : ElementBuilder<ClipElement>, ElementSelector<ClipElement> {
+        override fun build(): ClipElement = ClipElement()
+        override fun trySelect(element: Element): ClipElement? = element as? ClipElement
+    }
+}

kanvas/src/nativeDarwinMain/kotlin/CGContextKanvas.kt

@@ -97,9 +97,11 @@ public class CGContextKanvas(
 
     override fun pushClip(clip: Clip) {
         CGContextSaveGState(unmanagedContext)
-        CGContextBeginPath(unmanagedContext)
-        clip.path.withCGPath { cgPath ->
-            CGContextAddPath(unmanagedContext, cgPath)
+        withInverseY {
+            CGContextBeginPath(unmanagedContext)
+            clip.path.withCGPath { cgPath ->
+                CGContextAddPath(unmanagedContext, cgPath)
+            }
         }
         CGContextClip(unmanagedContext)
     }