[orx-delegate-magic, orx-envelopes] Add orx-delegate-magic, orx-envelopes

orx-delegate-magic/src/commonMain/kotlin/tracking/PropertyTracker.kt

@@ -0,0 +1,39 @@
+@file:Suppress("PackageDirectoryMismatch")
+
+package org.openrndr.extra.delegatemagic.tracking
+
+import org.openrndr.Program
+import kotlin.reflect.KProperty
+import kotlin.reflect.KProperty0
+
+class PropertyTracker<T>(private val program: Program, private val property: KProperty0<T>, val length: Int = 30) {
+    private val track = mutableListOf<T>()
+    private var lastTime: Double? = null
+
+    operator fun getValue(any: Any?, property: KProperty<*>): List<T> {
+        if (lastTime != null) {
+            val dt = program.seconds - lastTime!!
+            if (dt > 1E-10) {
+                track.add(this.property.get())
+            }
+        } else {
+            track.add(this.property.get())
+        }
+        if (track.size > length) {
+            track.removeAt(0)
+        }
+        lastTime = program.seconds
+        return track
+    }
+}
+
+/**
+ * Create a property tracker
+ * @param property the property to track
+ * @param length the maximum length of the tracked history
+ * @return a property tracker
+ * @since 0.4.3
+ */
+fun <T> Program.tracking(property: KProperty0<T>, length: Int = 30): PropertyTracker<T> {
+    return PropertyTracker(this, property, length)
+}