From 1fac718a58d571f52c2e99c6c67dd21070b5d2e6 Mon Sep 17 00:00:00 2001
From: Shiva Prasad <sp@shiv19.com>
Date: Thu, 19 Jul 2018 19:10:59 +0530
Subject: [PATCH] feat(UI): Added animated scroll to index for ListView (#6077)

* feat(UI): Added animated scroll to index for ListView

* Update list-view.d.ts
---
 tns-core-modules/ui/list-view/list-view-common.ts  | 4 ++++
 tns-core-modules/ui/list-view/list-view.android.ts | 7 +++++++
 tns-core-modules/ui/list-view/list-view.d.ts       | 8 ++++++++
 tns-core-modules/ui/list-view/list-view.ios.ts     | 7 +++++++
 4 files changed, 26 insertions(+)

diff --git a/tns-core-modules/ui/list-view/list-view-common.ts b/tns-core-modules/ui/list-view/list-view-common.ts
index 6f468aa01..447fc09ef 100644
--- a/tns-core-modules/ui/list-view/list-view-common.ts
+++ b/tns-core-modules/ui/list-view/list-view-common.ts
@@ -90,6 +90,10 @@ export abstract class ListViewBase extends View implements ListViewDefinition, T
         //
     }
 
+    public scrollToIndexAnimated(index: number) {
+        //
+    }
+
     public _getItemTemplate(index: number): KeyedTemplate {
         let templateKey = "default";
         if (this.itemTemplateSelector) {
diff --git a/tns-core-modules/ui/list-view/list-view.android.ts b/tns-core-modules/ui/list-view/list-view.android.ts
index 8cc6528f0..46023cf5a 100644
--- a/tns-core-modules/ui/list-view/list-view.android.ts
+++ b/tns-core-modules/ui/list-view/list-view.android.ts
@@ -124,6 +124,13 @@ export class ListView extends ListViewBase {
         }
     }
 
+    public scrollToIndexAnimated(index: number) {
+        const nativeView = this.nativeViewProtected;
+        if (nativeView) {
+            nativeView.smoothScrollToPosition(index);
+        }
+    }
+
     get _childrenCount(): number {
         return this._realizedItems.size;
     }
diff --git a/tns-core-modules/ui/list-view/list-view.d.ts b/tns-core-modules/ui/list-view/list-view.d.ts
index 08db3a021..b64181693 100644
--- a/tns-core-modules/ui/list-view/list-view.d.ts
+++ b/tns-core-modules/ui/list-view/list-view.d.ts
@@ -97,6 +97,14 @@ export class ListView extends View {
      */
     scrollToIndex(index: number);
 
+    /**
+     * Scrolls the specified item with index into view with animation. 
+     * [iOS](https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UITableView_Class/#//apple_ref/occ/instm/UITableView/scrollToRowAtIndexPath:atScrollPosition:animated:)
+     * [Android](https://developer.android.com/reference/android/widget/ListView.html#smoothScrollToPosition(int))
+     * @param index - Item index. 
+     */
+    scrollToIndexAnimated(index: number);
+
     /**
      * Checks if Specified item with index is visible.
      * @param index - Item index.
diff --git a/tns-core-modules/ui/list-view/list-view.ios.ts b/tns-core-modules/ui/list-view/list-view.ios.ts
index 35b933327..8417d8682 100644
--- a/tns-core-modules/ui/list-view/list-view.ios.ts
+++ b/tns-core-modules/ui/list-view/list-view.ios.ts
@@ -261,6 +261,13 @@ export class ListView extends ListViewBase {
         }
     }
 
+    public scrollToIndexAnimated(index: number) {
+        if (this._ios) {
+            this._ios.scrollToRowAtIndexPathAtScrollPositionAnimated(NSIndexPath.indexPathForItemInSection(index, 0),
+                UITableViewScrollPosition.Top, true);
+        }
+    }
+
     public refresh() {
         // clear bindingContext when it is not observable because otherwise bindings to items won't reevaluate
         this._map.forEach((view, nativeView, map) => {