Plv render after first draw (#688)

* PLV now render after first onLayout

* ..

Co-authored-by: Talha Naqvi <talha.naqvi@shopify.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "recyclerlistview",
-  "version": "3.1.0-beta.3",
+  "version": "3.1.0-beta.4",
   "description": "The listview that you need and deserve. It was built for performance, uses cell recycling to achieve smooth scrolling.",
   "main": "dist/reactnative/index.js",
   "types": "dist/reactnative/index.d.ts",

src/core/ProgressiveListView.tsx

@@ -24,12 +24,23 @@ export default class ProgressiveListView extends RecyclerListView<ProgressiveLis
         renderAheadOffset: 0,
     };
     private renderAheadUdpateCallbackId?: number;
+    private isFirstLayoutComplete: boolean = false;
 
     public componentDidMount(): void {
-        if (super.componentDidMount) {
-            super.componentDidMount();
+        super.componentDidMount();
+        if (!this.props.forceNonDeterministicRendering) {
+            this.updateRenderAheadProgessively(this.getCurrentRenderAheadOffset());
         }
-        this.updateRenderAheadProgessively(this.getCurrentRenderAheadOffset());
+    }
+
+    protected onItemLayout(index: number): void {
+        if (!this.isFirstLayoutComplete) {
+            this.isFirstLayoutComplete = true;
+            if (this.props.forceNonDeterministicRendering) {
+                this.updateRenderAheadProgessively(this.getCurrentRenderAheadOffset());
+            }
+        }
+        super.onItemLayout(index);
     }
 
     private updateRenderAheadProgessively(newVal: number): void {

src/core/RecyclerListView.tsx

@@ -391,6 +391,15 @@ export default class RecyclerListView<P extends RecyclerListViewProps, S extends
     protected getVirtualRenderer(): VirtualRenderer {
         return this._virtualRenderer;
     }
+    protected onItemLayout(index: number): void {
+        if (this.props.onItemLayout) {
+            this.props.onItemLayout(index);
+        }
+    }
+
+    private _onItemLayout = (index: number) => {
+        this.onItemLayout(index);
+    }
 
     private _processInitialOffset(): void {
         if (this._pendingScrollToOffset) {
@@ -630,7 +639,7 @@ export default class RecyclerListView<P extends RecyclerListViewProps, S extends
                     extendedState={this.props.extendedState}
                     internalSnapshot={this.state.internalSnapshot}
                     renderItemContainer={this.props.renderItemContainer}
-                    onItemLayout={this.props.onItemLayout}/>
+                    onItemLayout={this._onItemLayout}/>
             );
         }
         return null;
@@ -829,5 +838,6 @@ RecyclerListView.propTypes = {
     // This can be used to hook an itemLayoutListener to listen to which item at what index is layout.
     // To get the layout params of the item, you can use the ref to call method getLayout(index), e.x. : `this._recyclerRef.getLayout(index)`
     // but there is a catch here, since there might be a pending relayout due to which the queried layout might not be precise.
+    // Caution: RLV only listens to layout changes if forceNonDeterministicRendering is true
     onItemLayout: PropTypes.func,
 };