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tldraw/apps/vscode/README.md
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2023-04-25 12:01:25 +01:00

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@tldraw/vscode

This folder contains the source for the tldraw VS Code extension.

Developing

1. Install dependencies

  • Run yarn from the root folder

2. Start the editor

In the root folder:

  • Run yarn dev:vscode.

This will start the development server for the apps/vscode/editor project and open the apps/vscode/extension folder in a new VS Code window.

In the apps/vscode/extension window, open the terminal and:

  • Install dependencies (yarn)
  • Start the VS Code debugger (Menu > Run > Start Debugging or by pressing F5). This will open another VS Code window with the extension running.

Open a .tldr file from the file explorer or create a new .tldr file from the command palette.

3. Debugging

You can use standard debugging techniques like console.log, which will be displayed in the VS Code window with the extension running. It will display logs both from the Extension and the Editor. VS Code editor with the Extension folder will show more detailed logs from the Extension project. You can also use a debugger.

The code is hot-reloaded, so the developer experience is quite nice.

Publishing

Update the CHANGELOG.md with the new version number and the changes.

To publish:

In the apps/vscode/extension folder:

  • Run yarn package
  • Run yarn publish

Project overview

The Visual Studio Code extension is made of two projects:

1. Extension project

Extension project is under apps/vscode/extension and contains the code needed to run a VS Code Extension - it implements the required VS Code interfaces so that VS Code can call our extension and start running it.

It registers the command for generating a new .tldr file, custom editor for .tldr files, and it communicates with the WebViews that run @tldraw/editor (more on this later on).

VS Code Extension API offers two ways for adding new editors: CustomEditor and CustomTextEditor. We are using CustomEditor, even though it means we have to do a bit more work and maintain the contents of the document ourselves. This allows us to better support features like undo, redo, and revert, since we are in complete control of the contents of the document.

The custom editor logic lives in TldrawDocument, where we handle all the required custom editor operations like reading the file from disk, saving the file, backups, reverting, etc. When a .tldr file is opened a new instance of a TldrawDocument is created and this instance then serves as the underlying document model for displaying in the VS Code editors for editing this file. You can open the same file in multiple editors, but even then only a single instance of TldrawDocument is created per file.

When a users opens a file a new WebView is created by the TldrawWebviewManager and the file's contents are sent do it. WebViews then show our editor project, which is described below.

2. Editor project

Editor project is under apps/vscode/editor. When a file is opened a new instance of a WebView is created and we show @tldraw/editor this WebView.

The implementation is pretty straight forward, but there are some limitations of running tldraw inside a WebView, like window.open and window.prompt not being available, as well as some issues with embeds. We are using useLocalSyncClient to sync between different editor instances for cases when the same file is opened in multiple editors.

When users interact with tldraw we listen for changes and when changes happen we serialize the document contents and send them over to TldrawDocument. This makes VS Code aware of the changes and allows users to use built in features like save, save as, undo, redo, and revert.

Overview of the communication between VS Code, Extension, and the Editor

VS Code actives our extension when needed - when a user opens the first .tldr file or when a user runs our registered command. Then, VS Code calls into TldrawEditorProvider to open the custom editor, which in turn creates a TldrawDocument instance. We read the file contents from disk and send them to the WebView, which then shows the Editor. When the user interacts with the editor we send the changes back to the Extension, which then updates the TldrawDocument instance. Since the instance is always kept up to date we can correctly handle user actions like save, save as, undo, redo, and revert.

VS Code Extension

References