Add find visible items for list and flowlayout

doric-demo/src/FlowLayoutDemo.ts

@@ -41,6 +41,7 @@ class FlowDemo extends Panel {
                     }).also(it => {
                         if (idx == 15) {
                             it.fullSpan = true
+                            it.identifier = "fullSpan"
                         }
                     })
             },
@@ -62,7 +63,14 @@ class FlowDemo extends Panel {
                     height: 50,
                     fullSpan: true,
                     layoutConfig: layoutConfig().configWidth(LayoutSpec.MOST),
-                })
+                }),
+            onScrollEnd: async () => {
+                const ret = await flowView.findCompletelyVisibleItems(context)
+                loge('completelyVisible Items is:', ret)
+
+                const ret2 = await flowView.findVisibleItems(context)
+                loge('visible Items is:', ret2)
+            }
         }).in(rootView)
 
     }

doric-demo/src/ListDemo.ts

@@ -111,6 +111,12 @@ class ListVM extends ViewModel<ListModel, ListVH> {
                     state.data = state.data.concat(ret.data)
                     state.offset = state.data.length
                 })
+            },
+            onScrollEnd: async () => {
+                const ret = await vh.list.findCompletelyVisibleItems(context)
+                loge('completelyVisible Items is:', ret)
+                const ret2 = await vh.list.findVisibleItems(context)
+                loge('visible Items is:', ret2)
             }
         })
         loadData(state.offset).then(ret => {