Package: Modifying text

This section will guide you though creating a simple command that replaces the selected text with ascii art. When you run our new command with the word "cool" selected, it will be replaced with:

                                     o888
    ooooooo     ooooooo     ooooooo   888
  888     888 888     888 888     888 888
  888         888     888 888     888 888
    88ooo888    88ooo88     88ooo88  o888o

This should demonstrate how to do basic text manipulation in the current text buffer and how to deal with selections.

The final package can be viewed at https://github.com/pulsar-edit/ascii-art.

Basic text insertion

To begin, press Ctrl+Shift+P Cmd+Shift+P to bring up the command palette. Type "generate package" and select the Package Generator: Generate Package command, just as we covered earlier. Enter ascii-art as the name of the package.

Now let’s edit the package files to make our ASCII art package do something interesting. Since this package doesn’t need any UI, we can remove all view-related code — so delete lib/ascii-art-view.js, spec/ascii-art-view-spec.js, and styles/.

Next, open up lib/ascii-art.js and remove all view code, so it looks like this:

const { CompositeDisposable } = require("atom");

module.exports = {
	subscriptions: null,

	activate() {
		this.subscriptions = new CompositeDisposable();
		this.subscriptions.add(
			atom.commands.add("atom-workspace", {
				"ascii-art:convert": () => this.convert(),
			})
		);
	},

	deactivate() {
		this.subscriptions.dispose();
	},

	convert() {
		console.log("Convert text!");
	},
};

Create a command

Now let’s add a command. You should namespace your commands with the package name followed by a : and then the name of the command. As you can see in the code, we called our command ascii-art:convert and we will define it to call the convert() method when it’s executed.

So far, that will simply log to the console. Let’s start by making it insert something into the text buffer.

convert() {
  const editor = atom.workspace.getActiveTextEditor()
  if (editor) {
    editor.insertText('Hello, World!')
  }
}

As in the last tutorial, we’re using atom.workspace.getActiveTextEditor() to get the object that represents the active text editor. If this convert() method is called when not focused on a text editor, nothing will happen.

Next we insert a string into the current text editor with the TextEditor::insertText method. This will insert the text wherever the cursor currently is in the current editor. If there are selections, it will replace all selections with the "Hello, World!" text.

Reload the package

Before we can trigger ascii-art:convert, we need to load the latest code for our package by reloading the window. Run the command Window: Reload from the Command Palette or by pressing Ctrl+Shift+F5 Alt+Cmd+Ctrl+L.

Trigger the command

Now open the command palette and search for the Ascii Art: Convert command. But it’s not there! To fix this, open package.json and find the property called activationCommands. Activation commands make Pulsar launch faster by allowing Pulsar to delay a package’s activation until it’s needed. So remove the existing command and use ascii-art:convert in activationCommands:

"activationCommands": {
  "atom-workspace": "ascii-art:convert"
}

First, reload the window by running the command "Window: Reload" from the command palette. Now when you run the Ascii Art: Convert command it will insert "Hello, World!" into the active editor, if any.

Add a key binding

Now let’s add a key binding to trigger the ascii-art:convert command. Open keymaps/ascii-art.json and add a key binding linking Alt+Ctrl+A to the ascii-art:convert command. You can delete the pre-existing key binding since you won’t need it anymore.

When finished, the file should look like this:

{
  "atom-text-editor": {
    "ctrl-alt-a": "ascii-art:convert"
  }
}

Now reload the window and verify that the key binding works.

Add the ASCII art

Now we need to convert the selected text to ASCII art. To do this we will use the figlet Node module from npm. Open package.json and add the latest version of figlet to the dependencies:

"dependencies": {
  "figlet": "1.0.8"
}

After saving the file, run the command Update Package Dependencies: Update from the command palette. This will install the package’s Node module dependencies, only figlet in this case. You will need to run Update Package Dependencies: Update whenever you update the dependencies field in your package.json file.

If for some reason this doesn’t work, you’ll see a message saying "Failed to update package dependencies" and you will find a new npm-debug.log file in your directory. That file should give you some idea as to what went wrong.

Now require the figlet node module in lib/ascii-art.js and instead of inserting "Hello, World!", convert the selected text to ASCII art.

convert () {
  const editor = atom.workspace.getActiveTextEditor()
  if (editor) {
    const selection = editor.getSelectedText()

    const figlet = require('figlet')
    const font = 'o8'
    figlet(selection, {font}, function (error, art) {
      if (error) {
        console.error(error)
      } else {
        editor.insertText(`\n${art}\n`)
      }
    })
  }
}

Now reload the editor, select some text in an editor window and press Alt+Ctrl+A. It should be replaced with a ridiculous ASCII art version instead.

There are a couple of new things in this example we should look at quickly. The first is the TextEditor::getSelectedText call — which, as you might guess, returns the text that is currently selected.

We then call the Figlet code to convert that into something else and replace the current selection with it with the TextEditor::insertText call.

Summary

In this section, we’ve made a UI-less package that takes selected text and replaces it with a processed version. This could be helpful in creating linters or checkers for your code.