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/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import * as vscode from 'vscode';
import { Disposable } from '../util/dispose';
import { isMarkdownFile } from '../util/file';
export interface LastScrollLocation {
readonly line: number;
readonly uri: vscode.Uri;
}
export class TopmostLineMonitor extends Disposable {
private readonly pendingUpdates = new Map<string, number>();
private readonly throttle = 50;
private previousTextEditorInfo = new Map<string, LastScrollLocation>();
private previousStaticEditorInfo = new Map<string, LastScrollLocation>();
constructor() {
super();
if (vscode.window.activeTextEditor) {
const line = getVisibleLine(vscode.window.activeTextEditor);
this.setPreviousTextEditorLine({ uri: vscode.window.activeTextEditor.document.uri, line: line ?? 0 });
}
this._register(vscode.window.onDidChangeTextEditorVisibleRanges(event => {
if (isMarkdownFile(event.textEditor.document)) {
const line = getVisibleLine(event.textEditor);
if (typeof line === 'number') {
this.updateLine(event.textEditor.document.uri, line);
this.setPreviousTextEditorLine({ uri: event.textEditor.document.uri, line: line });
}
}
}));
}
private readonly _onChanged = this._register(new vscode.EventEmitter<{ readonly resource: vscode.Uri; readonly line: number }>());
public readonly onDidChanged = this._onChanged.event;
public setPreviousStaticEditorLine(scrollLocation: LastScrollLocation): void {
this.previousStaticEditorInfo.set(scrollLocation.uri.toString(), scrollLocation);
}
public getPreviousStaticEditorLineByUri(resource: vscode.Uri): number | undefined {
const scrollLoc = this.previousStaticEditorInfo.get(resource.toString());
this.previousStaticEditorInfo.delete(resource.toString());
return scrollLoc?.line;
}
public setPreviousTextEditorLine(scrollLocation: LastScrollLocation): void {
this.previousTextEditorInfo.set(scrollLocation.uri.toString(), scrollLocation);
}
public getPreviousTextEditorLineByUri(resource: vscode.Uri): number | undefined {
const scrollLoc = this.previousTextEditorInfo.get(resource.toString());
this.previousTextEditorInfo.delete(resource.toString());
return scrollLoc?.line;
}
public getPreviousStaticTextEditorLineByUri(resource: vscode.Uri): number | undefined {
const state = this.previousStaticEditorInfo.get(resource.toString());
return state?.line;
}
public updateLine(
resource: vscode.Uri,
line: number
) {
const key = resource.toString();
if (!this.pendingUpdates.has(key)) {
// schedule update
setTimeout(() => {
if (this.pendingUpdates.has(key)) {
this._onChanged.fire({
resource,
line: this.pendingUpdates.get(key) as number
});
this.pendingUpdates.delete(key);
}
}, this.throttle);
}
this.pendingUpdates.set(key, line);
}
}
/**
* Get the top-most visible range of `editor`.
*
* Returns a fractional line number based the visible character within the line.
* Floor to get real line number
*/
export function getVisibleLine(
editor: vscode.TextEditor
): number | undefined {
if (!editor.visibleRanges.length) {
return undefined;
}
const firstVisiblePosition = editor.visibleRanges[0].start;
const lineNumber = firstVisiblePosition.line;
const line = editor.document.lineAt(lineNumber);
const progress = firstVisiblePosition.character / (line.text.length + 2);
return lineNumber + progress;
}
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