关于前端:Theia-技术揭秘之布局系统

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  • 基于 PhosphorJS 能够实现 桌面端 /Web 端对立实现类桌面的交互
  • 理解 PhosphorJS 的外围组件 Widget 的接口和实现
  • 理解 Theia 是如何基于 PhosphorJS 在 ApplicationShell 中进行页面组装的
  • 理解 Theia 前端界面是如何通过 FrontendApplication.start() 构建的
  • 理解 React 与 PhosphorJS 混写办法

Theia 框架前端 UI 布局和 Services 一样,具备灵便可拓展的特点。VSCode 是内置了一套根本的组件零碎,而 Theia 框架的 UI 布局基于 PhosphorJS 框架。PhosphorJS 提供了蕴含 widgets、layouts、事件和数据结构的丰盛工具包。这使得开发人员可能构建可扩大的、高性能的、类桌面的 Web 应用程序,比方 JupyterLab。

PhosphorJS 作者退休,我的项目已归档,该我的项目当初被 Jupyter 团队重命名为 jupyterlab/lumino 持续保护。见 issue:https://github.com/jupyterlab…

成果

example-dockpanel

在 PhosphorJS 里运行 React 代码:ermalism/phosphorjs-react-jsx-example

Widget

PhosphorJS 布局的外围就在于 Widget。

这里的 Widget 和 Flutter 外面的 Widget 还不一样,Flutter 的 Widget 属于申明式 UI(declarative UI),而 PhosphorJS 的 Widget 更像是命令式 UI(imperative UI)。和 Chrome 开发者工具 ChromeDevTools/devtools-frontend 的 Widget 更相似。

对于申明式和命令式 UI 框架也能够浏览:聊聊我对古代前端框架的认知 作为补充。

Widget 的继承

官网提供了一系列 Widget 的继承实现:

Widget

- Panel  //  面板,wrapper around PanelLayout
    - BoxPanel  // wrapper around a BoxLayout , 将子 widgets 依照行或列的形式排列
    - SplitPanel  // wrapper around a SplitLayout , arranges its widgets into resizable sections.
    - StackedPanel  // wrapper around a StackedLayout , visible widgets are stacked atop one another
- CommandPalette // displays command items as a searchable palette
- Menu // displays items as a canonical menu
- TabBar // displays titles as a single row or column of tabs
- DockPanel // 提供灵便的 docking area
- MenuBar // canonical menu bar
- ScrollBar // canonical scroll bar
- TabPanel // combines a TabBar and a StackedPanel

并且都实现了 IDisposable 和 IMessageHandler 接口。

接口

Widget 蕴含以下状态:isDisposed、isAttached、isHidden、isVisible,以及一系列事件驱动的钩子:onCloseRequest、onResize、onUpdateRequest、onFitRequest、onActivateRequest、onBeforeShow、onBeforeHide、onBeforeAttach、onBeforeDetach、onChildAdded 等。

渲染的外围的办法在于 Widget.attach,实质上就是:host.insertBefore(widget.node, ref);

Widget 次要的字段及接口如下:

/**
 * The namespace for the `Widget` class statics.
 */
export declare namespace Widget {
    /**
     * Construct a new widget.
     *
     * @param options - The options for initializing the widget.
     */
    constructor(options?: Widget.IOptions);

    /**
     * Get the DOM node owned by the widget.
     */
    readonly node: HTMLElement;

    readonly title: Title<Widget>;

    parent: Widget | null;

    layout: Layout | null;

    children(): IIterator<Widget>;

    /**
     * Post an `'update-request'` message to the widget.
     *
     * #### Notes
     * This is a simple convenience method for posting the message.
     */
    update(): void;

    /**
     * Attach a widget to a host DOM node.
     *
     * @param widget - The widget of interest.
     *
     * @param host - The DOM node to use as the widget's host.
     *
     * @param ref - The child of `host` to use as the reference element.
     *   If this is provided, the widget will be inserted before this
     *   node in the host. The default is `null`, which will cause the
     *   widget to be added as the last child of the host.
     */
    function attach(widget: Widget, host: HTMLElement, ref?: HTMLElement | null): void;
}

Theia 布局构建

Theia 前端页面的启动非常简单:

function start() {(window['theia'] = window['theia'] || {}).container = container;

    const themeService = ThemeService.get();
    themeService.loadUserTheme();

    const application = container.get(FrontendApplication);
    return application.start();}

能够看到外围就在于 FrontendApplication.start() 办法,那么这个办法里做了什么?

FrontendApplication

// packages/core/src/browser/frontend-application.ts
@injectable()
export class FrontendApplication {
    
    /**
     * Start the frontend application.
     *
     * Start up consists of the following steps:
     * - start frontend contributions
     * - attach the application shell to the host element
     * - initialize the application shell layout
     * - reveal the application shell if it was hidden by a startup indicator
     */
    async start(): Promise<void> {await this.startContributions();
        this.stateService.state = 'started_contributions';

        const host = await this.getHost();
        this.attachShell(host);
        await animationFrame();
        this.stateService.state = 'attached_shell';

        await this.initializeLayout();
        this.stateService.state = 'initialized_layout';
        await this.fireOnDidInitializeLayout();

        await this.revealShell(host);
        this.registerEventListeners();
        this.stateService.state = 'ready';
    }

    /**
     * Attach the application shell to the host element. If a startup indicator is present, the shell is
     * inserted before that indicator so it is not visible yet.
     */
    protected attachShell(host: HTMLElement): void {const ref = this.getStartupIndicator(host);
        Widget.attach(this.shell, host, ref);  // 实质是调用  host.insertBefore(widget.node, ref);
    }
}

ApplicationShell

次要分为:mainPanel:TheiaDockPanel、topPanel:Panel、bottomPanel:TheiaDockPanel、leftPanel、rightPanel

    /**
     * General options for the application shell. These are passed on construction and can be modified
     * through dependency injection (`ApplicationShellOptions` symbol).
     */
    export interface Options extends Widget.IOptions {
        bottomPanel: BottomPanelOptions;
        leftPanel: SidePanel.Options;
        rightPanel: SidePanel.Options;
    }
    export interface BottomPanelOptions extends SidePanel.Options { }

    /**
     * The default values for application shell options.
     */
    export const DEFAULT_OPTIONS = Object.freeze(<Options>{
        bottomPanel: Object.freeze(<BottomPanelOptions>{
            emptySize: 140,
            expandThreshold: 160,
            expandDuration: 0,
            initialSizeRatio: 0.382
        }),
        leftPanel: Object.freeze(<SidePanel.Options>{
            emptySize: 140,
            expandThreshold: 140,
            expandDuration: 0,
            initialSizeRatio: 0.191
        }),
        rightPanel: Object.freeze(<SidePanel.Options>{
            emptySize: 140,
            expandThreshold: 140,
            expandDuration: 0,
            initialSizeRatio: 0.191
        })
    });

在 ApplicationShell 中初始化并拼装。

// packages/core/src/browser/shell/application-shell.ts
/**
 * The application shell manages the top-level widgets of the application. Use this class to
 * add, remove, or activate a widget.
 */
@injectable()
export class ApplicationShell extends Widget {
    /**
     * Construct a new application shell.
     */
    constructor(@inject(DockPanelRendererFactory) protected dockPanelRendererFactory: () => DockPanelRenderer,
        @inject(StatusBarImpl) protected readonly statusBar: StatusBarImpl,
        @inject(SidePanelHandlerFactory) sidePanelHandlerFactory: () => SidePanelHandler,
        @inject(SplitPositionHandler) protected splitPositionHandler: SplitPositionHandler,
        @inject(FrontendApplicationStateService) protected readonly applicationStateService: FrontendApplicationStateService,
        @inject(ApplicationShellOptions) @optional() options: RecursivePartial<ApplicationShell.Options> = {}
    ) {super(options as Widget.IOptions);
        this.addClass(APPLICATION_SHELL_CLASS);
        this.id = 'theia-app-shell';

        // Merge the user-defined application options with the default options
        this.options = {
            bottomPanel: {
                ...ApplicationShell.DEFAULT_OPTIONS.bottomPanel,
                ...options.bottomPanel || {}},
            leftPanel: {
                ...ApplicationShell.DEFAULT_OPTIONS.leftPanel,
                ...options.leftPanel || {}},
            rightPanel: {
                ...ApplicationShell.DEFAULT_OPTIONS.rightPanel,
                ...options.rightPanel || {}}
        };

        this.mainPanel = this.createMainPanel();
        this.topPanel = this.createTopPanel();
        this.bottomPanel = this.createBottomPanel();

        this.leftPanelHandler = sidePanelHandlerFactory();
        this.leftPanelHandler.create('left', this.options.leftPanel);
        this.leftPanelHandler.dockPanel.widgetAdded.connect((_, widget) => this.fireDidAddWidget(widget));
        this.leftPanelHandler.dockPanel.widgetRemoved.connect((_, widget) => this.fireDidRemoveWidget(widget));

        this.rightPanelHandler = sidePanelHandlerFactory();
        this.rightPanelHandler.create('right', this.options.rightPanel);
        this.rightPanelHandler.dockPanel.widgetAdded.connect((_, widget) => this.fireDidAddWidget(widget));
        this.rightPanelHandler.dockPanel.widgetRemoved.connect((_, widget) => this.fireDidRemoveWidget(widget));

        this.layout = this.createLayout();

        this.tracker.currentChanged.connect(this.onCurrentChanged, this);
        this.tracker.activeChanged.connect(this.onActiveChanged, this);
    }

    /**
     * Assemble the application shell layout. Override this method in order to change the arrangement
     * of the main area and the side panels.  Layout 创立
     */
    protected createLayout(): Layout {
        const bottomSplitLayout = this.createSplitLayout([this.mainPanel, this.bottomPanel],
            [1, 0],
            {orientation: 'vertical', spacing: 0}
        );
        const panelForBottomArea = new SplitPanel({layout: bottomSplitLayout});
        panelForBottomArea.id = 'theia-bottom-split-panel';

        const leftRightSplitLayout = this.createSplitLayout([this.leftPanelHandler.container, panelForBottomArea, this.rightPanelHandler.container],
            [0, 1, 0],
            {orientation: 'horizontal', spacing: 0}
        );
        const panelForSideAreas = new SplitPanel({layout: leftRightSplitLayout});
        panelForSideAreas.id = 'theia-left-right-split-panel';

        return this.createBoxLayout([this.topPanel, panelForSideAreas, this.statusBar],
            [0, 1, 0],
            {direction: 'top-to-bottom', spacing: 0}
        );
    }

    /**
     * Create the dock panel in the main shell area.  Panel 创立
     */
    protected createMainPanel(): TheiaDockPanel {const renderer = this.dockPanelRendererFactory();
        renderer.tabBarClasses.push(MAIN_BOTTOM_AREA_CLASS);
        renderer.tabBarClasses.push(MAIN_AREA_CLASS);
        const dockPanel = new TheiaDockPanel({
            mode: 'multiple-document',
            renderer,
            spacing: 0
        });
        dockPanel.id = MAIN_AREA_ID;
        dockPanel.widgetAdded.connect((_, widget) => this.fireDidAddWidget(widget));
        dockPanel.widgetRemoved.connect((_, widget) => this.fireDidRemoveWidget(widget));
        return dockPanel;
    }
}

Plugin API 里的 Widget 创立

Node/Browser API 的 Widget 创立:通过 WidgetFactory。

    bind(WidgetFactory).toDynamicValue(({container}) => ({
        id: PLUGIN_VIEW_DATA_FACTORY_ID,
        createWidget: (identifier: TreeViewWidgetIdentifier) => {
            const child = createTreeContainer(container, {
                contextMenuPath: VIEW_ITEM_CONTEXT_MENU,
                globalSelection: true
            });
            child.bind(TreeViewWidgetIdentifier).toConstantValue(identifier);
            child.bind(PluginTree).toSelf();
            child.rebind(TreeImpl).toService(PluginTree);
            child.bind(PluginTreeModel).toSelf();
            child.rebind(TreeModelImpl).toService(PluginTreeModel);
            child.bind(TreeViewWidget).toSelf();
            child.rebind(TreeWidget).toService(TreeViewWidget);
            return child.get(TreeWidget);
        }
    })).inSingletonScope();

    bind(WidgetFactory).toDynamicValue(({container}) => ({
        id: PLUGIN_VIEW_FACTORY_ID,
        createWidget: (identifier: PluginViewWidgetIdentifier) => {const child = container.createChild();
            child.bind(PluginViewWidgetIdentifier).toConstantValue(identifier);
            return child.get(PluginViewWidget);
        }
    })).inSingletonScope();

    bind(WidgetFactory).toDynamicValue(({container}) => ({
        id: PLUGIN_VIEW_CONTAINER_FACTORY_ID,
        createWidget: (identifier: ViewContainerIdentifier) =>
            container.get<ViewContainer.Factory>(ViewContainer.Factory)(identifier)
    })).inSingletonScope();

Packages

commands

Class CommandRegistry 治理命令汇合的对象。用于 CommandRegistry 类 statics 的命名空间。

命令注册表可用于填充各种 action-based widgets,如命令 palettes、menus 和 toolbars。

import {CommandRegistry} from '@phosphor/commands'

const commands = new CommandRegistry()

commands.addCommand('cut', {
  label: 'Cut',
  mnemonic: 1,
  icon: 'fa fa-cut',
  execute: () => {console.log('Cut')
  },
})

commands.addCommand('default-theme', {
  label: 'Default theme',
  mnemonic: 0,
  icon: 'fa fa-paint-brush',
  execute: () => {console.log('Default theme')
  },
})

let ctxt = new Menu({commands})
ctxt.addItem({command: 'copy'})

let toggle = new Toggle({onLabel: 'Dark', offLabel: 'Light', command: 'dark-toggle', commands: commands})
toggle.id = 'daylightToggle'
bar.node.appendChild(toggle.node)

Widgets 与 React

将 React 组件封装成 Widget 组件

思路:

  1. extends Widget
  2. 在 onUpdateRequest 生命周期中 ReactDOM.render JSX 到 widget node

而后当作自定义的 Widget 应用即可。

Theia 已提供形象组件 ReactWidgt 供参考:packages/core/src/browser/widgets/react-widget.tsx

/********************************************************************************
 * Copyright (C) 2018 TypeFox and others.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the Eclipse
 * Public License v. 2.0 are satisfied: GNU General Public License, version 2
 * with the GNU Classpath Exception which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 ********************************************************************************/

import * as ReactDOM from 'react-dom';
import * as React from 'react';
import {injectable, unmanaged} from 'inversify';
import {DisposableCollection, Disposable} from '../../common';
import {BaseWidget, Message} from './widget';
import {Widget} from '@phosphor/widgets';

@injectable()
export abstract class ReactWidget extends BaseWidget {protected readonly onRender = new DisposableCollection();

    constructor(@unmanaged() options?: Widget.IOptions) {super(options);
        this.scrollOptions = {
            suppressScrollX: true,
            minScrollbarLength: 35,
        };
        this.toDispose.push(Disposable.create(() => {ReactDOM.unmountComponentAtNode(this.node);
        }));
    }

    protected onUpdateRequest(msg: Message): void {super.onUpdateRequest(msg);
        ReactDOM.render(<React.Fragment>{this.render()}</React.Fragment>, this.node, () => this.onRender.dispose());
    }

    /**
     * Render the React widget in the DOM.
     * - If the widget has been previously rendered,
     * any subsequent calls will perform an update and only
     * change the DOM if absolutely necessary.
     */
    protected abstract render(): React.ReactNode;}

将 Widget 封装成 React 组件

  1. 创立 widget 组件
  2. 通过 React.createProtal() 将 this.props.children 渲染到 widget.node
  3. 将间接应用 React 组件
  4. 父组件通过 context 传递本身办法,在 componentDidMount 生命周期中,通过 parent.receiveChild(this.widget) 将以后组件 widget 渲染

import * as PropTypes from "prop-types";
import * as React from "react";
import {createPortal} from "react-dom";

import {Widget} from "@phosphor/widgets/lib/widget";

import {Title} from "@phosphor/widgets/lib/title";

require("@phosphor/widgets/style/widget.css");

import {WidgetParentContext, IWidgetParent} from "./Common";

export interface IWidgetProps {title?: Partial<Title.IOptions<Widget>>;}

export default class ReactWidget extends React.PureComponent<IWidgetProps, {}> {
  private widget: Widget;

  // TODO: aah why isn't this working
  // Some indication that this may be unstable (i.e. worked on 16.6.3 but not 16.6.1)
  // https://stackoverflow.com/questions/53110121/react-new-context-api-not-working-with-class-contexttype-but-works-with-conte
  static contextType = WidgetParentContext;
  contextType = WidgetParentContext;

  private storedContext: IWidgetParent;

  constructor(props) {super(props);
    this.widget = new Widget();

    ReactWidget.setTitleKeys(this.widget, {}, props);
  }

  componentDidMount() {
    let parent = this.storedContext;
    if (!parent) throw new Error("ReactWidget must be wrapped in a container component (BoxPanel, SplitPanel, etc.)");

    parent.receiveChild(this.widget);
  }

  componentDidUpdate(prevProps: IWidgetProps) {ReactWidget.setTitleKeys(this.widget, prevProps, this.props);
  }

  static setTitleKeys(widget: Widget, prevProps: IWidgetProps, props: IWidgetProps) {let titleKeys: (keyof Title.IOptions<Widget>)[] = ["caption", "className", "closable", "dataset", "icon", "iconClass", "iconLabel", "label", "mnemonic"];

    for (let k of titleKeys) {if ((prevProps.title || {})[k as any] !== (props.title || {})[k as any]) {widget.title[k as any] = props.title[k as any];
      }
    }
  }

  render() {
    return createPortal(
      <div>
          <p>
              <WidgetParentContext.Consumer>
                  {(value) => {this.storedContext = value; return null;}}
              </WidgetParentContext.Consumer>
          </p>
          {this.props.children}
      </div>,
      this.widget.node
    );
  }
}

或者参考:Run a PhosphorJS DockerPanel with Widgets INSIDE a React component

参考

  • PhosphorJS Docs
  • PhosphorJS Examples
  • ermalism/phosphorjs-react-jsx-example
  • codedownio/react-phosphorjs
  • jupyterlab/lumino
  • Lumino API Documentation
  • Using Lumino in a Vue.js application
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