Merge "Implement .add( controller ) & its use for custom Controllers" from dataarts#243.

Author: superkelvint

example.html

@@ -58,6 +58,44 @@
     var f3 = f2.addFolder('Nested Folder');
     f3.add(obj, 'growthSpeed');
 
+    //  alternative StringController add
+    gui.add(new dat.controllers.StringController(obj, 'message'));
+
+    //  a custom controller
+    class KnobController extends dat.controllers.Controller {
+      constructor(object, property, a, b) {
+        super(object, property);
+        const _this = this;
+        this.__input = document.createElement('input');
+        this.__input.setAttribute('type', 'number');
+        this.__input.style.width = '40%';
+        this.updateDisplay();
+        this.domElement.appendChild(this.__input);
+        var button = document.createElement('input');
+        button.setAttribute('type', 'button');
+        button.value = 'Set ' + property;
+        button.style.width = '50%';
+        button.onclick = function(e) {
+          object[property] = a + b;
+          _this.updateDisplay();
+        };
+        this.domElement.appendChild(button);
+      }
+      updateDisplay() {
+        this.__input.value = this.getValue();
+      }
+    }
+
+    const api = {
+
+      color: '#ffffff',
+      value: 0.5,
+
+    };
+
+    gui.add(new KnobController(api, 'value', 0.5, 25), {
+      liClass: 'knobby'
+    });
   </script>
 </body>
 </html>

src/dat/gui/GUI.js

@@ -1128,19 +1128,23 @@ function recallSavedValue(gui, controller) {
 }
 
 function add(gui, object, property, params) {
-  if (object[property] === undefined) {
-    throw new Error(`Object "${object}" has no property "${property}"`);
-  }
-
   let controller;
 
-  if (params.color) {
-    controller = new ColorController(object, property);
-  } else if (params.image) {
-    controller = new ImageController(object, property, params.factoryArgs[0]);
-  } else {
-    const factoryArgs = [object, property].concat(params.factoryArgs);
-    controller = ControllerFactory.apply(gui, factoryArgs);
+  if (object instanceof Controller) {
+    controller = object;
+    params = property || { };
+  }  else {
+
+    if (object[property] === undefined) {
+      throw new Error(`Object "${object}" has no property "${property}"`);
+    }
+
+    if (params.color) {
+      controller = new ColorController(object, property);
+    } else {
+      const factoryArgs = [object, property].concat(params.factoryArgs);
+      controller = ControllerFactory.apply(gui, factoryArgs);
+    }
   }
 
   if (params.before instanceof Controller) {
@@ -1164,6 +1168,10 @@ function add(gui, object, property, params) {
   dom.addClass(li, GUI.CLASS_CONTROLLER_ROW);
   if (controller instanceof ColorController) {
     dom.addClass(li, 'color');
+  } else if ( params.liClass ) {
+    dom.addClass(li, params.liClass);
+  } else if ( controller.liClass ) {
+    dom.addClass(li, controller.liClass);
   } else if (controller instanceof ImageController) {
     dom.addClass(li, 'image');
   } else {