list add findVisibleItems api

doric-android/doric/src/main/java/pub/doric/shader/flowlayout/FlowLayoutNode.java

@@ -20,6 +20,7 @@ import android.text.TextUtils;
 import android.view.View;
 
 import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 import androidx.recyclerview.widget.StaggeredGridLayoutManager;
 
@@ -28,6 +29,9 @@ import com.github.pengfeizhou.jscore.JSONBuilder;
 import com.github.pengfeizhou.jscore.JSObject;
 import com.github.pengfeizhou.jscore.JSValue;
 
+import org.json.JSONArray;
+import org.json.JSONObject;
+
 import java.util.HashSet;
 import java.util.Set;
 import java.util.concurrent.Callable;
@@ -36,6 +40,7 @@ import pub.doric.DoricContext;
 import pub.doric.DoricScrollChangeListener;
 import pub.doric.IDoricScrollable;
 import pub.doric.async.AsyncResult;
+import pub.doric.extension.bridge.DoricMethod;
 import pub.doric.extension.bridge.DoricPlugin;
 import pub.doric.shader.SuperNode;
 import pub.doric.shader.ViewNode;
@@ -326,6 +331,53 @@ public class FlowLayoutNode extends SuperNode<RecyclerView> implements IDoricScr
         listeners.remove(listener);
     }
 
+    private int calibratePosition(int position) {
+        if (hasHeader() && position == 0) {
+            return -11;
+        }
+        if (hasFooter() && position == this.itemCount
+                + (this.loadMore ? 1 : 0)
+                + (this.hasHeader() ? 1 : 0)
+                + (this.hasFooter() ? 1 : 0) - 1) {
+            return -12;
+        }
+        if (position >= this.itemCount + (this.hasHeader() ? 1 : 0)) {
+            return -10;
+        }
+        if (this.hasHeader()) {
+            return position - 1;
+        }
+        return position;
+    }
+
+    @DoricMethod
+    public JSONArray findVisibleItems() {
+        int[] startPos = staggeredGridLayoutManager.findFirstVisibleItemPositions(null);
+        int[] endPos = staggeredGridLayoutManager.findLastVisibleItemPositions(null);
+        JSONArray jsonArray = new JSONArray();
+        for (int i = 0; i < staggeredGridLayoutManager.getSpanCount(); i++) {
+            jsonArray.put(new JSONBuilder()
+                    .put("first", calibratePosition(startPos[i]))
+                    .put("last", calibratePosition(endPos[i]))
+                    .toJSONObject());
+        }
+        return jsonArray;
+    }
+
+    @DoricMethod
+    public JSONArray findCompletelyVisibleItems() {
+        int[] startPos = staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(null);
+        int[] endPos = staggeredGridLayoutManager.findFirstCompletelyVisibleItemPositions(null);
+        JSONArray jsonArray = new JSONArray();
+        for (int i = 0; i < staggeredGridLayoutManager.getSpanCount(); i++) {
+            jsonArray.put(new JSONBuilder()
+                    .put("first", calibratePosition(startPos[i]))
+                    .put("last", calibratePosition(endPos[i]))
+                    .toJSONObject());
+        }
+        return jsonArray;
+    }
+
     boolean hasHeader() {
         return !TextUtils.isEmpty(this.headerViewId);
     }

doric-android/doric/src/main/java/pub/doric/shader/list/ListNode.java

@@ -26,12 +26,15 @@ import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
+import com.github.pengfeizhou.jscore.JSArray;
 import com.github.pengfeizhou.jscore.JSDecoder;
 import com.github.pengfeizhou.jscore.JSNumber;
 import com.github.pengfeizhou.jscore.JSONBuilder;
 import com.github.pengfeizhou.jscore.JSObject;
 import com.github.pengfeizhou.jscore.JSValue;
 
+import org.json.JSONObject;
+
 import java.util.HashSet;
 import java.util.Set;
 import java.util.concurrent.Callable;
@@ -300,6 +303,47 @@ public class ListNode extends SuperNode<RecyclerView> implements IDoricScrollabl
         moveToPosition(pos.toInt(), animated);
     }
 
+    private int calibratePosition(int position) {
+        if (hasHeader() && position == 0) {
+            return -11;
+        }
+        if (hasFooter() && position == this.itemCount
+                + (this.loadMore ? 1 : 0)
+                + (this.hasHeader() ? 1 : 0)
+                + (this.hasFooter() ? 1 : 0) - 1) {
+            return -12;
+        }
+        if (position >= this.itemCount + (this.hasHeader() ? 1 : 0)) {
+            return -10;
+        }
+        if (this.hasHeader()) {
+            return position - 1;
+        }
+        return position;
+    }
+
+    @DoricMethod
+    public JSONObject findVisibleItems() {
+        LinearLayoutManager linearLayoutManager = (LinearLayoutManager) this.mView.getLayoutManager();
+        assert linearLayoutManager != null;
+        int startPos = linearLayoutManager.findFirstVisibleItemPosition();
+        int endPos = linearLayoutManager.findLastVisibleItemPosition();
+        return new JSONBuilder()
+                .put("first", calibratePosition(startPos))
+                .put("last", calibratePosition(endPos)).toJSONObject();
+    }
+
+    @DoricMethod
+    public JSONObject findCompletelyVisibleItems() {
+        LinearLayoutManager linearLayoutManager = (LinearLayoutManager) this.mView.getLayoutManager();
+        assert linearLayoutManager != null;
+        int startPos = linearLayoutManager.findFirstCompletelyVisibleItemPosition();
+        int endPos = linearLayoutManager.findLastCompletelyVisibleItemPosition();
+        return new JSONBuilder()
+                .put("first", calibratePosition(startPos))
+                .put("last", calibratePosition(endPos)).toJSONObject();
+    }
+
     private void moveToPosition(int pos, boolean smooth) {
         if (mView.getLayoutManager() == null) {
             return;

doric-js/src/widget/flowlayout.ts

@@ -16,6 +16,7 @@
 import { Stack } from './layouts'
 import { Property, Superview, View, NativeViewModel } from '../ui/view'
 import { layoutConfig } from '../util/index.util'
+import { BridgeContext } from '../..'
 
 export class FlowLayoutItem extends Stack {
     /**
@@ -94,6 +95,21 @@ export class FlowLayout extends Superview {
 
     @Property
     footer?: FlowLayoutItem
+    /**
+     * @param context 
+     * @returns Returns the range of the visible views for each column.
+     */
+    findVisibleItems(context: BridgeContext) {
+        return this.nativeChannel(context, 'findVisibleItems')() as Promise<{ first: number, last: number }[]>
+    }
+    /**
+     * @param context 
+     * @returns Returns the range of the completely visible views for each column.
+     */
+    findCompletelyVisibleItems(context: BridgeContext) {
+        return this.nativeChannel(context, 'findCompletelyVisibleItems')() as Promise<{ first: number, last: number }[]>
+    }
+
 
     reset() {
         this.cachedViews.clear()

doric-js/src/widget/list.ts

@@ -35,6 +35,12 @@ export class ListItem extends Stack {
     }[]
 }
 
+export enum OtherItems {
+    LoadMore = -10,
+    Header = -11,
+    Footer = -12,
+}
+
 export class List extends Superview {
     private cachedViews: Map<string, ListItem> = new Map
 
@@ -97,6 +103,20 @@ export class List extends Superview {
         const animated = config?.animated
         return this.nativeChannel(context, 'scrollToItem')({ index, animated, }) as Promise<any>
     }
+    /**
+     * @param context 
+     * @returns Returns the range of the visible views.
+     */
+    findVisibleItems(context: BridgeContext) {
+        return this.nativeChannel(context, 'findVisibleItems')() as Promise<{ first: number, last: number }>
+    }
+    /**
+     * @param context 
+     * @returns Returns the range of the completely visible views.
+     */
+    findCompletelyVisibleItems(context: BridgeContext) {
+        return this.nativeChannel(context, 'findCompletelyVisibleItems')() as Promise<{ first: number, last: number }>
+    }
 
     reset() {
         this.cachedViews.clear()