Disable command list.scrollUp/scrollDown when the list scrollbar is at boundary

Author: hsfzxjy

src/vs/platform/list/browser/listService.ts

@@ -113,6 +113,14 @@ export class ListService implements IListService {
 	}
 }
 
+export const RawWorkbenchListScrollAtBoundaryContextKey = new RawContextKey<'none' | 'top' | 'bottom' | 'both'>('listScrollAtBoundary', 'none');
+export const WorkbenchListScrollAtTopContextKey = ContextKeyExpr.or(
+	RawWorkbenchListScrollAtBoundaryContextKey.isEqualTo('top'),
+	RawWorkbenchListScrollAtBoundaryContextKey.isEqualTo('both'));
+export const WorkbenchListScrollAtBottomContextKey = ContextKeyExpr.or(
+	RawWorkbenchListScrollAtBoundaryContextKey.isEqualTo('bottom'),
+	RawWorkbenchListScrollAtBoundaryContextKey.isEqualTo('both'));
+
 export const RawWorkbenchListFocusContextKey = new RawContextKey<boolean>('listFocus', true);
 export const WorkbenchListSupportsMultiSelectContextKey = new RawContextKey<boolean>('listSupportsMultiselect', true);
 export const WorkbenchListFocusContextKey = ContextKeyExpr.and(RawWorkbenchListFocusContextKey, ContextKeyExpr.not(InputFocusedContextKey));
@@ -139,6 +147,33 @@ function createScopedContextKeyService(contextKeyService: IContextKeyService, wi
 	return result;
 }
 
+// Note: We must declare IScrollObservarable as the arithmetic of concrete classes,
+// instead of object type like { onDidScroll: Event<any>; ... }. The latter will not mark
+// those properties as referenced during tree-shaking, causing them to be shaked away.
+type IScrollObservarable = Exclude<WorkbenchListWidget, WorkbenchPagedList<any>> | List<any>;
+
+function createScrollObserver(contextKeyService: IContextKeyService, widget: IScrollObservarable): IDisposable {
+	const listScrollAt = RawWorkbenchListScrollAtBoundaryContextKey.bindTo(contextKeyService);
+	const update = () => {
+		const atTop = widget.scrollTop === 0;
+
+		// We need a threshold `1` since scrollHeight is rounded.
+		// https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollHeight#determine_if_an_element_has_been_totally_scrolled
+		const atBottom = widget.scrollHeight - widget.renderHeight - widget.scrollTop < 1;
+		if (atTop && atBottom) {
+			listScrollAt.set('both');
+		} else if (atTop) {
+			listScrollAt.set('top');
+		} else if (atBottom) {
+			listScrollAt.set('bottom');
+		} else {
+			listScrollAt.set('none');
+		}
+	};
+	update();
+	return widget.onDidScroll(update);
+}
+
 const multiSelectModifierSettingKey = 'workbench.list.multiSelectModifier';
 const openModeSettingKey = 'workbench.list.openMode';
 const horizontalScrollingKey = 'workbench.list.horizontalScrolling';
@@ -259,6 +294,8 @@ export class WorkbenchList<T> extends List<T> {
 
 		this.contextKeyService = createScopedContextKeyService(contextKeyService, this);
 
+		this.disposables.add(createScrollObserver(this.contextKeyService, this));
+
 		this.listSupportsMultiSelect = WorkbenchListSupportsMultiSelectContextKey.bindTo(this.contextKeyService);
 		this.listSupportsMultiSelect.set(options.multipleSelectionSupport !== false);
 
@@ -390,6 +427,8 @@ export class WorkbenchPagedList<T> extends PagedList<T> {
 
 		this.contextKeyService = createScopedContextKeyService(contextKeyService, this);
 
+		this.disposables.add(createScrollObserver(this.contextKeyService, this.widget));
+
 		this.horizontalScrolling = options.horizontalScrolling;
 
 		this.listSupportsMultiSelect = WorkbenchListSupportsMultiSelectContextKey.bindTo(this.contextKeyService);
@@ -514,6 +553,8 @@ export class WorkbenchTable<TRow> extends Table<TRow> {
 
 		this.contextKeyService = createScopedContextKeyService(contextKeyService, this);
 
+		this.disposables.add(createScrollObserver(this.contextKeyService, this));
+
 		this.listSupportsMultiSelect = WorkbenchListSupportsMultiSelectContextKey.bindTo(this.contextKeyService);
 		this.listSupportsMultiSelect.set(options.multipleSelectionSupport !== false);
 
@@ -1165,6 +1206,8 @@ class WorkbenchTreeInternals<TInput, T, TFilterData> {
 	) {
 		this.contextKeyService = createScopedContextKeyService(contextKeyService, tree);
 
+		this.disposables.push(createScrollObserver(this.contextKeyService, tree));
+
 		this.listSupportsMultiSelect = WorkbenchListSupportsMultiSelectContextKey.bindTo(this.contextKeyService);
 		this.listSupportsMultiSelect.set(options.multipleSelectionSupport !== false);
 

src/vs/workbench/browser/actions/listCommands.ts

@@ -7,7 +7,7 @@ import { KeyMod, KeyCode } from 'vs/base/common/keyCodes';
 import { ServicesAccessor } from 'vs/platform/instantiation/common/instantiation';
 import { KeybindingsRegistry, KeybindingWeight } from 'vs/platform/keybinding/common/keybindingsRegistry';
 import { List } from 'vs/base/browser/ui/list/listWidget';
-import { WorkbenchListFocusContextKey, IListService, WorkbenchListSupportsMultiSelectContextKey, ListWidget, WorkbenchListHasSelectionOrFocus, getSelectionKeyboardEvent, WorkbenchListWidget, WorkbenchListSelectionNavigation, WorkbenchTreeElementCanCollapse, WorkbenchTreeElementHasParent, WorkbenchTreeElementHasChild, WorkbenchTreeElementCanExpand, RawWorkbenchListFocusContextKey, WorkbenchTreeFindOpen, WorkbenchListSupportsFind } from 'vs/platform/list/browser/listService';
+import { WorkbenchListFocusContextKey, IListService, WorkbenchListSupportsMultiSelectContextKey, ListWidget, WorkbenchListHasSelectionOrFocus, getSelectionKeyboardEvent, WorkbenchListWidget, WorkbenchListSelectionNavigation, WorkbenchTreeElementCanCollapse, WorkbenchTreeElementHasParent, WorkbenchTreeElementHasChild, WorkbenchTreeElementCanExpand, RawWorkbenchListFocusContextKey, WorkbenchTreeFindOpen, WorkbenchListSupportsFind, WorkbenchListScrollAtBottomContextKey, WorkbenchListScrollAtTopContextKey } from 'vs/platform/list/browser/listService';
 import { PagedList } from 'vs/base/browser/ui/list/listPaging';
 import { equals, range } from 'vs/base/common/arrays';
 import { ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
@@ -692,7 +692,12 @@ KeybindingsRegistry.registerCommandAndKeybindingRule({
 KeybindingsRegistry.registerCommandAndKeybindingRule({
 	id: 'list.scrollUp',
 	weight: KeybindingWeight.WorkbenchContrib,
-	when: WorkbenchListFocusContextKey,
+	// Since the default keybindings for list.scrollUp and widgetNavigation.focusPrevious
+	// are both Ctrl+UpArrow, we disable this command when the scrollbar is at
+	// top-most position. This will give chance for widgetNavigation.focusPrevious to execute
+	when: ContextKeyExpr.and(
+		WorkbenchListFocusContextKey,
+		WorkbenchListScrollAtTopContextKey?.negate()),
 	primary: KeyMod.CtrlCmd | KeyCode.UpArrow,
 	handler: accessor => {
 		const focused = accessor.get(IListService).lastFocusedList;
@@ -708,7 +713,10 @@ KeybindingsRegistry.registerCommandAndKeybindingRule({
 KeybindingsRegistry.registerCommandAndKeybindingRule({
 	id: 'list.scrollDown',
 	weight: KeybindingWeight.WorkbenchContrib,
-	when: WorkbenchListFocusContextKey,
+	// same as above
+	when: ContextKeyExpr.and(
+		WorkbenchListFocusContextKey,
+		WorkbenchListScrollAtBottomContextKey?.negate()),
 	primary: KeyMod.CtrlCmd | KeyCode.DownArrow,
 	handler: accessor => {
 		const focused = accessor.get(IListService).lastFocusedList;