generalize EntrySpriteSystem into PlaygroundSystem which all ui will provide

src/nat/ArchiveController.kiss

@@ -162,6 +162,10 @@
     (archive.addSystem (new ImageAttachmentSystem))
     (archive.addSystem (new KeyShortcutSystem this))
     (archive.addSystem (new DLSystem))
+    (whenLet [ps (ui.playgroundSystem)]
+        (archive.addSystem ps)
+        // TODO allow saving a different default playground
+        (ps.switchPlaygroundKey "Playground-MAIN"))
 
     // Just for testing:
     // (archive.addSystem (new AttachmentSystem ["jpg" "jpeg" "png"] ->[archive e files] ~files))

src/nat/ArchiveUI.hx

@@ -3,6 +3,7 @@ package nat;
 import nat.Entry;
 import nat.ArchiveController;
 import kiss_tools.KeyShortcutHandler;
+import nat.systems.PlaygroundSystem;
 
 interface ArchiveUI {
     /**
@@ -15,6 +16,11 @@ interface ArchiveUI {
      */
     var shortcutHandler(default, null):Null<KeyShortcutHandler<Entry>>;
 
+    /**
+     * A PlaygroundSystem that will display interactible entry representations
+     */
+    function playgroundSystem():Null<PlaygroundSystem>;
+
     /**
      * Prompt the user to enter text
      */

src/nat/components/Position.hx

@@ -0,0 +1,3 @@
+package nat.components;
+
+typedef Position = {x:Float, y:Float, z:Float};

src/nat/components/Positions.hx

@@ -1,6 +1,7 @@
 package nat.components;
 
+
 /**
  * Entries can have multiple positions in different UIs/folders/whatever.
  */
-typedef Positions = Map<String, {x:Float, y:Float, z:Float}>;
+typedef Positions = Map<String, Position>;

src/nat/systems/PlaygroundSystem.hx

@@ -0,0 +1,15 @@
+package nat.systems;
+
+import kiss.Prelude;
+import kiss.List;
+import nat.System;
+import nat.components.Position;
+
+typedef PlaygroundEntryProcessor = (Archive, Entry, Position, ?ArchiveUI) -> Dynamic; // Whatever value is returned will be dropped, but this is easier than requiring ->:Void
+
+/**
+ * Base class for Systems that process Entries in a playground view and displays them in an interactive form
+ * (EntrySpriteSystem, for example)
+ */
+@:build(kiss.Kiss.build())
+class PlaygroundSystem extends System {}

src/nat/systems/PlaygroundSystem.kiss

@@ -0,0 +1,37 @@
+(load "../Lib.kiss")
+
+(prop &mut :String _playgroundKey "")
+(method :String getPlaygroundKey [] _playgroundKey)
+
+(defNew [&prop :ArchiveUI ui
+            :EntryChecker canProcess
+            &prop :PlaygroundEntryProcessor processor]
+
+    (super
+        ->[archive e]
+            (and (tagsMatch e "!(or done hidden)") (canProcess archive e))
+        ->[archive e &opt ui]
+            {
+                (when !(hasComponent e Positions)
+                    (addComponent archive e Positions (new Map)))
+                (withWritableComponents archive e [positions Positions]
+                    (when !(positions.exists _playgroundKey)
+                        // TODO do a playground check before giving a default position.
+                        (dictSet positions _playgroundKey (defaultPosition e))))
+                (let [pos (dictGet (readComponent e Positions) _playgroundKey)]
+                    (processor archive e pos ui))
+            }))
+
+(method switchPlaygroundKey [key]
+    (when _playgroundKey
+        (clear))
+    (set _playgroundKey key)
+    (process ui.controller.archive ui))
+
+(method clear [])
+
+(method &override :Void process [:Archive archive &opt :ArchiveUI ui]
+    (when _playgroundKey (super.process archive ui)))
+
+(method defaultPosition [:Entry e]
+    (object x 0.0 y 0.0 z 0.0))