feat:scroller add onScroll and onScrollEnd property

doric-js/src/pattern/mvvm.ts

@@ -35,6 +35,10 @@ export abstract class ViewModel<M extends Object, V extends ViewHolder> {
         return this.state
     }
 
+    getViewHolder() {
+        return this.viewHolder;
+    }
+
     updateState(setter: Setter<M>) {
         setter(this.state)
         this.onBind(this.state, this.viewHolder)

doric-js/src/widget/scroller.ts

@@ -40,6 +40,12 @@ export class Scroller extends Superview implements IScroller {
     @Property
     contentOffset?: { x: number, y: number }
 
+    @Property
+    onScroll?: (offset: { x: number, y: number }) => void
+
+    @Property
+    onScrollEnd?: (offset: { x: number, y: number }) => void
+
     allSubviews() {
         return [this.content]
     }