From 275d2a02ca922738b58cea7dbf9dce229ea75f21 Mon Sep 17 00:00:00 2001
From: Joao Moreno <joao.moreno@microsoft.com>
Date: Fri, 22 Feb 2019 10:05:54 +0100
Subject: [PATCH] fixes #64749

---
 src/vs/base/browser/ui/list/listView.ts      | 10 ++++++++++
 src/vs/base/browser/ui/list/listWidget.ts    |  8 ++++++++
 src/vs/base/browser/ui/tree/abstractTree.ts  | 12 ++++++++++++
 src/vs/base/browser/ui/tree/asyncDataTree.ts |  8 ++++++++
 4 files changed, 38 insertions(+)

diff --git a/src/vs/base/browser/ui/list/listView.ts b/src/vs/base/browser/ui/list/listView.ts
index 73ca98dabcf..513fddb0126 100644
--- a/src/vs/base/browser/ui/list/listView.ts
+++ b/src/vs/base/browser/ui/list/listView.ts
@@ -431,6 +431,16 @@ export class ListView<T> implements ISpliceable<T>, IDisposable {
 		return scrollDimensions.height;
 	}
 
+	get firstVisibleIndex(): number {
+		const range = this.getRenderRange(this.lastRenderTop, this.lastRenderHeight);
+		return range.start;
+	}
+
+	get lastVisibleIndex(): number {
+		const range = this.getRenderRange(this.lastRenderTop, this.lastRenderHeight);
+		return range.end - 1;
+	}
+
 	element(index: number): T {
 		return this.items[index].element;
 	}
diff --git a/src/vs/base/browser/ui/list/listWidget.ts b/src/vs/base/browser/ui/list/listWidget.ts
index 69ccfbbdb3c..1f36e8a2f10 100644
--- a/src/vs/base/browser/ui/list/listWidget.ts
+++ b/src/vs/base/browser/ui/list/listWidget.ts
@@ -1308,6 +1308,14 @@ export class List<T> implements ISpliceable<T>, IDisposable {
 		return this.view.renderHeight;
 	}
 
+	get firstVisibleIndex(): number {
+		return this.view.firstVisibleIndex;
+	}
+
+	get lastVisibleIndex(): number {
+		return this.view.lastVisibleIndex;
+	}
+
 	domFocus(): void {
 		this.view.domNode.focus();
 	}
diff --git a/src/vs/base/browser/ui/tree/abstractTree.ts b/src/vs/base/browser/ui/tree/abstractTree.ts
index 08a218b4d54..5b3273a7b8f 100644
--- a/src/vs/base/browser/ui/tree/abstractTree.ts
+++ b/src/vs/base/browser/ui/tree/abstractTree.ts
@@ -1090,6 +1090,18 @@ export abstract class AbstractTree<T, TFilterData, TRef> implements IDisposable
 		return this.view.renderHeight;
 	}
 
+	get firstVisibleElement(): T {
+		const index = this.view.firstVisibleIndex;
+		const node = this.view.element(index);
+		return node.element;
+	}
+
+	get lastVisibleElement(): T {
+		const index = this.view.lastVisibleIndex;
+		const node = this.view.element(index);
+		return node.element;
+	}
+
 	domFocus(): void {
 		this.view.domFocus();
 	}
diff --git a/src/vs/base/browser/ui/tree/asyncDataTree.ts b/src/vs/base/browser/ui/tree/asyncDataTree.ts
index da776a66b4e..12ed97d4497 100644
--- a/src/vs/base/browser/ui/tree/asyncDataTree.ts
+++ b/src/vs/base/browser/ui/tree/asyncDataTree.ts
@@ -372,6 +372,14 @@ export class AsyncDataTree<TInput, T, TFilterData = void> implements IDisposable
 		return this.tree.renderHeight;
 	}
 
+	get firstVisibleElement(): T {
+		return this.tree.firstVisibleElement!.element as T;
+	}
+
+	get lastVisibleElement(): T {
+		return this.tree.lastVisibleElement!.element as T;
+	}
+
 	domFocus(): void {
 		this.tree.domFocus();
 	}
-- 
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